The Elements of Evolution (98) Glossary


~ : approximately.


3-age system: an archeological sequential periodization of human prehistory and early history, comprising the Stone Age, Bronze Age, and Iron Age.

4D (aka spacetime): the 4 dimensions of everyday experience: 3 of space (3d) + 1 of time. See HD and ED.


acacia (aka thorntree, wattle, whistling thorn): a genus of shrubs and trees with 1,300 species, 960 of which are endemic to Australia. Whereas many non-Australian species are thorny, most Australian acacias are not.

acacia spider (Bagheera kiplingi): a mostly vegetarian jumping spider, fond of Beltian bodies which make up 90% of its diet. Nectar and stolen ant larvae supplement the spider’s food intake.

acetate (C2H3O2): a salt formed by combining acetic acid with a base.

achene: small, hard, dry, indehiscent fruit containing a single seed which nearly fills the pericarp but does not adhere to it. Though a fruit, achenes are often referred to as seeds, as they appear seed-like, because the fruit hardens.

Acheulean (industry): late Old Stone Age tool technology during the time of Homo erectus. Acheulean industry represented refinements from the Oldowan. The term Acheulean refers to Saint-Acheul: a suburb of the town Amiens in northern France, 120 km north of Paris. See Mousterian industry.

acid: a proton donor. Contrast base.

acidophile: an organism that lives in a highly acidic habitat.

acritarch: fossils of archaea, bacteria, and single-celled eukaryotes from 3.2 BYA; more generally used as a taxon for early single-cell life: archaic prokaryotic microbes.

active margin: an active area of tectonic plates colliding. Contrast passive margin.

active site (microbiology): the position on a protein where substrates bind and undergo a chemical reaction.

adaptation (evolutionary biology): the teleological process of adjusting to ecological circumstance.

adaptive radiation: speciation to exploit divergent environments.

adenine (A) (C5H5N5): a nucleobase of DNA & RNA, complementary to thymine in DNA or uracil in RNA.

adipose fin: a small, soft, fleshy fin found on the back of a fish, behind the dorsal fin and just in front of the caudal fin.

ADP (adenosine diphosphate (C10H15N5O10P2)): the product of ATP dephosphorylation, which provides energy for a cell. See ATP.

adumbration: a sketch; an imperfect portrayal; a representation.

Aegean Sea: a large bay of the Mediterranean Sea between the southern Balkan and Anatolian peninsulas.

aerobic: living with oxygen. Contrast anaerobic.

aerobic respiration: cellular respiration which employs oxygen. Contrast anaerobic respiration.

aerosol: a suspension of fine liquid or solid particles in gas. Aerosol particles are less than 1 micrometer in diameter.

age (geology): a duration in the geological time scale, millions of years; shorter than an epoch.

aglomerular (kidney): a kidney without glomeruli to perform the 1st stage of blood filtration. Glomeruli are the intertwined capillaries that filter blood to make urine.

agriculture: the cultivation of one life form by another.

Agulhas Current: a swift Indian Ocean gyral current, carrying warm water clockwise.

aka: “also known as.”

albatross: a large seabird of 21 species in the Diomedeidae family, endemic to the Southern Ocean and north Pacific Ocean.

alga (plural: algae): a eukaryotic protist that photosynthesizes via chloroplasts. Algae are usually unicellular or colonial.

algorithm: a step-by-step procedure, often employed for mathematical problems. Compare heuristic.

Alice in Wonderland: an 1865 fantasy novel by Lewis Carroll about a young girl that falls down a rabbit hole to a surreal world where 2 sister queens conflict over who should reign.

aliphatic compound: a group of hydrocarbons that do not link together to form a ring.

alkaliphile: an organism that lives in a highly alkaline habitat.

alkane: a hydrocarbon bonded exclusively by single bonds.

alkene: a hydrocarbon with double bonds between carbon atoms.

allatostatin: a neuropeptide hormone in insects and crustaceans employed in growth control.

allele (aka allelomorph): one of multiple forms of a gene; a variation of a gene at the same locus. Selfsame alleles at a locus are homozygous; if different, heterozygous.

Allen’s rule: an 1877 hypothesis by Joel Allen that endotherms in colder climates tend to have shorter limbs or appendages than similar species who live in the tropics.

allergen: a substance which can cause an allergic reaction.

Allerød oscillation (14.0–~12.8 TYA): the interstadial period between the Older Dryas and Younger Dryas stadials. The Allerød oscillation is named after the town on Sjælland, the largest island in Denmark, where soil samples first identified the period (work published in 1901).

allogamy: cross-fertilization. Contrast autogamy.

allometry: growth of a body part relative to the entire organism; also the study thereof.

alloparenting: individuals other than biological parents acting as youngling caretakers.

allopatric speciation (aka vicariance): evolution of a single species into 2 distinct species owing to populations being isolated from each other. Contrast parapatric speciation, sympatry.

allopatry: the relationship (even conceptual, such as cladistically) between organism populations in separate geographic areas. Compare parapatry, sympatry.

allopolyploidy: polyploidy involving chromosomes of different species.

allosaur: a family of large theropod dinosaurs that lived during the Jurassic and Cretaceous periods.

allotetraploidy: polyploidy in a hybrid that carries the chromosomes of both parents.

Alpine (aka mountain or highland): a climate too cold for trees (above the tree line).

Alpine orogeny: an orogenic phase during the Late Mesozoic (Eoalpine) into the Cenozoic that formed the mountain ranges of the Alpide belt, caused by collisions between the African-Arabian plate and the Eurasian plate. The mountains in the Alpide belt (from west to east): Atlas, Rif, Baetic Cordillera, Cantabrian Mountains, Pyrenees, Alps, Apennine Mountains, Dinaric Alps, Hellenides, Carpathians, Balkan Mountains, Taurus, Armenian Highlands, Caucasus, Alborz, Zagros, Hindu Kush, Pamir, Karakoram, and Himalayas.

altricial: animals that are relatively immature and immobile at birth or hatching, and so require parental care. Many mammals are altricial. Contrast precocial.

altruism: unselfish behavior.

aluminum (Al): the element with the atomic number 13; a soft, ductile, silvery-white, nonmagnetic metal; the 3rd-most abundant element in Earth’s crust (after oxygen and silicon (silica)), and the most abundant metal. For a metal, aluminum has remarkably low density.

alluvium: silt, sand, clay, gravel, or similar detrital material deposited by running water.

alveolus (plural: alveoli) (lung anatomy): a spherical sac for gas exchange in the lungs of mammals. Compare septum.

Amarna (aka el-Amarna): the capital city of Egypt under Pharaoh Akhenaten (~1343 bce).

Amazonia: the Amazon basin of South America, naturally comprising rainforest.

American lobster (Homarus americanus): a species of lobster found off the coast of North America in the Atlantic Ocean from Labrador to New Jersey. See lobster.

ametabolous: a type of metamorphosis in which physical development proceeds largely as growth in size. Compare hemimetabolous, holometabolous.

amine: a derivative of ammonia.

amino acid: an organic molecule comprising a carboxylic acid group, an amine group, and a side chain specific to the specific amino acid. The key elements in amino acids are carbon, hydrogen, oxygen, and nitrogen, with other elements found in the side chain.

ammonia (NH3; aka azane): a toxic colorless gas with a pungent smell that figures in biology because of its nitrogen content. In certain microbes, atmospheric nitrogen is converted into ammonia by enzymes termed nitrogenases, in a process called nitrogen fixation. Mammals have a mechanism to prevent the buildup of ammonia toxicity in the bloodstream. Fish and amphibians lack this mechanism, as they can eliminate ammonia by excretions. For other aquatic animals, even dilute concentrations of ammonia are highly toxic.

amniote: a group of tetrapods that lay eggs on land or carry their eggs within females.

amoeba (plural: amoebas or amoebae): a protozoan with flexible form.

amphibian: a class of ectothermic tetrapod vertebrates that lay non-amniotic eggs; includes frogs, salamanders, and newts.

ampullae of Lorenzini: electrical current sense organs in cartilaginous fish (sharks, rays, and chimaeras); named after Stefano Lorenzini.

anabolism: the metabolic pathways for constructing biopolymers. See biosynthesis. Contrast catabolism.

anacoustic zone: an area where sound does not carry.

anaerobe: an organism that does not require oxygen.

anaerobic: living without oxygen. Contrast aerobic.

anaerobic respiration: cellular respiration without oxygen. Anaerobic respiration is less efficient than aerobic respiration.

analogue (evolutionary biology): a selfsame trait evolving independently in unrelated organisms – that is, convergent evolution. Contrast homologue.

anaphase: the stage of cell division where replicated chromosomes split, and 2 daughter chromatids migrate to opposite poles of a cell.

Anatolia (aka Asia Minor): the westernmost protrusion of Asia, comprising most of modern-day Turkey. Anatolia is bounded by the Black Sea to the north, the Mediterranean Sea to the south and the Aegean Sea to the west. The eastern border of Anatolia was a line between the Gulf of Alexandretta and the Black Sea, east of the Armenian highlands.

Andes (aka Andean Mountains): a 7,000 km continuous range of highlands along the western coast of South America; the longest continental mountain range in the world. The Andes include the world’s highest volcanoes.

anemophily: pollination via the wind.

angiosperm: a flowering plant, descended from gymnosperms. Angiosperms arose 245 MYA., incorporating several innovations, including leaves, pollen, flowers, and fruit. Angiosperm proliferation began 144 MYA. Over 254,000 species are extant.

anhydrobiosis: desiccation tolerance in an organism (typically aquatic) or life form, such as a plant seed.

animal: a kingdom of eukaryotic heterotrophs. Most animals are motile. The other kingdoms of eukaryotes are fungi, plants, and protists.

animism: the doctrine that that there is no separation between the physical and spiritual world, and that a vital energetic force is inherent in all of Nature. Contrast vitalism.

annelid (aka ringed worm, segmented worm): a phylum (Annelida) of segmented worms and leeches, with over 17,000 extant species, including ragworms, earthworms, and leeches.

anion: a negatively charged ion (indicating a surplus of electrons). Contrast cation.

annual (botany): an angiosperm that lives 1 year. Compare biennial, perennial. See herbaceous.

anole: a lizard in the Dactyloidae family, native to the warmer biomes of the Americas, typically green or brownish. Male anoles usually have a dewlap: an often brightly colored flap of skin which extends from the throat, used for communication displays.

anoxic (adjective): oxygen depleted.

ant: a colonial eusocial insect of ~22,000 extant species.

Antarctica: Earth’s southernmost continent, 14 million km2, the 5th largest continent. Antarctica is the coldest, driest, and windiest continent, as well as averaging the highest elevation.

Antarctic Circumpolar Current (ACC): an ocean current that flows clockwise, from west to east, around Antarctica. The ACC is the dominant circulation pattern of the Southern Ocean and the largest ocean current.

antelope: an even-toed bovid native to Africa and Eurasia.

anther: the pollen-producing reproductive organ of a flower.

anthozoa: a class of marine invertebrates which includes sea anemones, corals, sea fans, and sea whips. While larvae are motile as plankton, adult anthozoans are sessile: attached to the seabed.

anthropocentrism: an assessment of Nature via an exclusively human perspective, or an analysis from the perspective that humans are the most significant life form.

anthropoid: a monkey or ape. Compare hominid.

anthropology: the study of humans.

antibiosis: an antagonistic biological interaction where an organism produces an antibiotic against an infectious microbe.

antibiotic: a substance toxic to certain microbes.

antioxidant: a molecule that inhibits oxidation of other molecules.

Anurognathus: a genus of small pterosaur extant during the Late Jurassic.

Anzu: a large flightless oviraptorosauran dinosaur with a beaked skull and head crest.

ape (aka great ape): a tailless primate; not a monkey.

aphid (aka plant lice): an extraordinarily successful insect herbivore, comprising 4,400 species in 10 families. Aphids exist worldwide but are most populous in temperate zones. Aphids can migrate great distances by riding the winds.

Apoidea: a group of winged insects of 2 lineages: sphecoid wasps (Sphecidae) and bees (Anthophila). Sphecoid wasps include mud daubers, sand wasps, and other thread-waisted wasps.

apophallation: deliberate penis amputation by a hermaphroditic terrestrial gastropod mollusk after mating, if entwined penises cannot get untangled. The amputated penis does not grow back, but the slug may have sex in the future as a female.

apoptosis: programmed cell death. Compare necrosis.

aposematism: coloration that warns potential predators of toxicity. Contrast crypsis.

arachnid: the Arachnida class of invertebrates, with 8 jointed legs. There are over 100,000 named species, including spiders, harvestmen (aka opiliones, daddy longlegs), scorpions, solifuges (aka camel spiders, wind spiders), ticks, and mites.

aragonite (CaCO3): the orthorhombic mineral calcium carbonate, chemically identical to calcite but with different crystallization, a higher specific gravity, and less marked cleavage.

arboreal: inhabiting trees.

arborescent (botany): a plant with wood; a treelike plant. See herbaceous.

archaea (singular: archaeon): the robust and versatile group of prokaryotes from which eukaryotes arose; a taxonomic domain of life alongside bacteria and viruses.

Archaeopteryx (aka Urvogel): a genus of early bird, transitional between dinosaurs and modern birds.

Archean (3.9–2.5 BYA): the 2nd geological eon, when the atmosphere had little oxygen.

archeology (archaeology): the study of past human activity, especially prehistoric times, primarily through artifacts.

archipelago (aka island chain): a clustered group of islands.

archosaur: a group of egg-laying diapsids which includes extinct lineages including non-avian dinosaurs, many crocodilian relatives, and pterosaurs, along with living crocodiles and birds.

Ardipithecus (5.8–4.3 MYA): a genus of early hominin with modest stature and little sexual dimorphism. Ardipithecus spent time in the trees and on the ground.

arms race: (the idea of) 2 parties escalating their advantage in interacting with or competing against each other.

army ant: an ant of over 200 species that aggressively forages in predatory groups, known as raids, in which massive numbers roam over an area. Unlike most other ants, army ants do not construct residential nests. Instead they nomadically march, forming bivouacs as they travel.

arsenic (As): the element with atomic number 33; a metalloid that is essential nutrition in minute portions for some animals but toxic in larger quantities.

arthropod: an invertebrate with an exoskeleton, a segmented body, and jointed appendages. Arachnids, crustaceans, and insects are arthropods. There are over 6 million distinct arthropods. Arthropods comprise over 75% of animal species. Their collective biomass far outweighs that of vertebrates.

artiodactyl: an even-toed ungulate, including antelope, deer, pigs, hippopotamuses, camels, giraffes, sheep, goats, and cattle.

Aryan: an Indo-Iranian ethnic label dating to the Vedic period.

asexual reproduction: biological reproduction from a single parent.

aspen: a medium-sized deciduous tree native to cold regions with cool summers in the northern hemisphere. Aspens create long-lived clonal colonies. Aspen colonies survive forest fires. Fire indirectly helps aspens as it clears vegetation aboveground, allowing saplings open sunlight.

assortative mating: a mating pattern of preference for similarity.

asteroid: a small, rocky body orbiting the Sun. Most asteroids emerge from the asteroid belt between Mars and Jupiter.

asthenosphere: the layer of Earth’s upper mantle just below the lithosphere.

Atacama Desert: a 1,000-km desert plateau on the Pacific coast of South America which lies to the west of the Andes Mountains; 128,000 km2 in size, including the barren lower slopes of the Andes.

Atacameños: people who live in the Atacama Desert.

atavism: an evolutionary reversion to ancestral type.

atheistic naturalism: the belief that there is no God, only the material natural world.

atmosphere: the layer of gases that surround a body with enough mass to keep the gas layer. The atmosphere is held in place by the gravity of the body.

atom: the smallest particle of an element, comprising at the simplest a proton and an electron (hydrogen).

atomic decay: particulate radiation by subatomic particles from atomic nuclei. Compare beta decay.

atomic number: the number of protons an atom has.

Atopodentatus: a genus of marine reptile extant during the middle Triassic.

ATP (adenosine triphosphate): the cellular metabolic energy storage and intracellular energy transfer molecule. ATP is the universal cellular energy source. See ADP.

atresia: the breakdown of ovarian follicles (potential egg cells).

attine: a fungus-growing ant in the Attini tribe.

attosecond: 10–18 seconds.

audition: sound perception.

auk (aka alcid): a seabird related to terns and gulls. Auks can “fly” underwater as well as in the air. Though agile swimmers and divers, auks walk clumsily.

auricle (botany): an earlike pinna of a plant.

Australopithecus (4.2–1.8 MYA): a relatively long-lived genus of largely vegan hominins with considerable species diversity.

autogamy: self-fertilization. Contrast allogamy.

autolysis: (cellular) self-digestion.

autophagy: the catabolic process of recycling cellular waste.

autopoiesis: a dynamic of self-sustaining activity; a system capable of maintaining and reproducing itself. A biological cell sustaining itself is an example of autopoiesis. Compare homeostasis.

autopolyploidy: polyploidy via multiple chromosome sets derived from a single species.

autotroph: an organism that makes its own food. Autotrophs are lithotrophs or photoautotrophs. Lithotrophs consume electrons from inorganic chemicals for energy. Phototrophs take light as their primary energy source. Contrast heterotroph.

auxin: a class of plant hormones instrumental in numerous growth and behavioral processes.

aye-aye (Daubentonia madagascariensis): a nocturnal lemur endemic to Madagascar, with perpetually-growing rodent-like teeth and a thin middle finger which it uses to tap on trees to find grubs, whereupon an aye-aye gnaws its way in. The only other animal known to practice percussive foraging is the striped possum, a marsupial native to New Guinea.


baboon: a large African and Arabian (Old World) monkey of 5 species in the genus Papio, all having pronounced sexual dimorphism. Baboons possess the innate ability for literacy (orthographic processing skills).

background extinction: extinction limited to relatively few species. Contrast mass extinction.

bacteria (singular: bacterium): a taxonomic domain of single-celled prokaryotes, abundant in most ecosystems. Bacteria play vital roles in various facets of the biosphere.

bacteriophage (aka phage): a virus that infects bacteria.

Baja California: a peninsula south of California.

baker’s yeast (Saccharomyces cerevisiae): a yeast instrumental to brewing, winemaking, and baking since prehistoric times. The yeast was originally isolated from the skin of grapes.

Balanites wilsoniana: a tall fruit-bearing forest tree in west and central Africa. The fruit is eaten by elephants and gorillas.

bald eagle: a large bird of prey endemic to North America; an opportunistic feeder, mostly of fish. Bald eagles build the largest nest of any North American bird, and the largest nest in trees of any bird.

Baldwin effect: the effect of learning on evolution, discovered by Douglas Spalding in 1873; rediscovered and proposed by James Mark Baldwin in 1896; called the Baldwin effect by George Simpson in 1953.

baleen: a pressure-based comb-like filter-feeding system inside the mouth of whales. The baleen plates employed for this feeding system are made of keratin.

baleen whale (aka great whale): a cetacean suborder of filter-feeding whales. Rather than having teeth, baleen whales feed by filtering water through baleen plates.

Balkan green lizard (Lacerta trilineata): a lacerta lizard native to the Mediterranean habitats in southeastern Europe and the Levant.

bamboo: a flowering perennial evergreen plant; the largest in the grass family.

barbule: a branch from a barb of a bird feather. Feather barbs are the first set of branches from a feather’s rachis (spine).

barnacle: a sessile marine arthropod with over 1,220 species.

basal (evolutionary biology): an originating organism group (clade) from which later groups evolved. The term primitive is commonly used as a synonym, but primitive has connotation of inferiority or lack of complexity, which is not necessarily so.

basal metabolic rate: energy consumption at rest.

basalt: a volcanic rock, typically rich in magnesium oxide and calcium oxide, and low in silicon dioxide and alkali oxides.

base: a proton acceptor. Contrast acid.

basement (rock): a rock below a sedimentary platform. Basement rock is igneous or metamorphic in origin.

bat: a mammal with forelimbs forming webbed wings. Bats are the only mammal capable of sustained flight. 1,240 bat species are known, 70% of which are insectivores.

bat bug: a blood-sucking insect parasite that primarily feeds on bats. Bat bugs are closely related to bed bugs.

Batesian mimicry: phenotypic imitation by a palatable species of another that is noxious. Named after Henry Bates, who gave the first scientific account of it.

bay: a large body of water connected to the sea formed by an inlet of land which blocks some waves.

baywing (aka baywind cowbird, Agelaioides badius): a medium-sized passerine native to South America. Unlike “true” cowbirds, the baywing is not a brood parasite.

bce (acronym for Before the Common Era): a semi-secular alternative designation for the calendar scheme introduced by Dionysius Exiguus, who respectively used bc (before Christ) and ad (anno Domini) to indicate times before and after the life of Jesus of Nazareth. Year zero is unused in both systems. Dates before 1 ce (common era) are indicated as bce. ce dates are typically not denoted.

Bdelloidea: a class of freshwater and soil rotifers that reproduce asexually via parthenogenesis.

beaver: a large, primarily nocturnal, semiaquatic rodent. The beaver is best known for its dam-building skills, which provide still, deep water as protection against predators, and for floating food and building materials.

The North American beaver once numbered over 60 million. Thanks to human slaughter for their fur and habitat destruction, 6 million may remain (as of 2007).

bedbug: a blood-sucking insect parasite. The common bed bug (Cimex lectularius) is notably fond of people.

bee: a flying insect of 20,000 species in the superfamily Apoidea. Bees, like ants, are a specialized form of wasp. Bees are best known for their product from pollinating flowering plants: honey. Bee sociality varies from solitary to eusocial. Bee eusociality evolved independently in different species.

bee hummingbird (aka zunzuncito, Helena hummingbird, Mellisuga helenae): a hummingbird endemic to the Cuban archipelago; the smallest bird, with females weighing 2.6 g and 6.1 cm long (slightly larger than males).

beetle: an insect with wings and shell-like body protection, in the order Coleoptera.

behave: to act or react in a certain way.

behavior: an attributable state of action or inaction.

Beltian body: a nutritious detachable tip found on the pinnules of certain acacia trees; named after their discoverer, Thomas Belt.

Benguela Current: a counterclockwise oceanic gyre in the Atlantic Ocean which carries cool water.

benthic zone (benthos): the ecological region at the bottom of the ocean or other water body, including the sediment surface and subsurface layers.

Bergmann’s rule: an ecogeographic hypothesis by Christian Bergman in 1847 that larger animals, especially endotherms, are found in colder biomes, and, conversely, species of smaller size are found in warmer regions.

Beringia: the episodic Bering land bridge between Siberia and Alaska.

Bernoulli’s principle: a fluid dynamics principle that a speed increase of fluid transpires with a decrease in pressure or a drop in the fluid’s potential energy; named after Daniel Bernoulli, who described the principle in 1738.

beta decay: radioactive decay; nuclear or particle transmutation caused by the weak force, causing emission of a neutrino (or antineutrino) and electron or positron. Compare atomic decay.

biased gene conversion: gene conversion where a certain allele is favored.

bilaterian: an animal with a longitudinal plane of symmetry and specialized internal organ systems.

bio-layering (evolutionary biology): evolution of increasing complexity while maintaining interdependence with legacy genes by providing an ordering of genetic information for adaptive employment. Bio-layering affords reversion evolution.

biodiversity: the diversity of life at every level. Compare species diversity.

bioelement: a planetary ecological element. The bioelements include the atmosphere, lithosphere, hydrosphere, and biota.

biennial (botany): an angiosperm that takes 2 years to complete its life cycle. A biennial grows vegetative structures – roots, stems, and leaves – in its 1st year, before going dormant during the colder months. Typically, biennials grow close to the ground, with leaves forming a rosette. Many biennials require vernalization before they will flower. Onions, carrots, and parsley are biennials. Contrast annual, perennial. See herbaceous.

biofilm: a colony of prokaryotes encased in a stabilizing polymer matrix, commonly known as slime.

biogeography: a perspective of patterns related to a geological context.

biogenesis: the birth of the biosphere.

biogerontology: the study of organism aging.

biology: the science of life.

bioluminescence: production and emission of light by a living organism.

biome: an area where organisms live with similar conditions, both geographically and climatically.

biomechanics: biological mechanics.

biota: the organisms in an environment.

biopolymer: a polymer produced by a cell.

biosonar: a synonym for echolocation.

biosphere: the global summation of the Earth’s ecosystems.

biosynthesis: the cellular construction process of converting substrates into more complex bioproducts. See anabolism.

biota: the organisms in an environment.

biotrophic: dependent upon another organism as a nutrient source.

bioturbation: displacement and mixing of sediment by fauna or flora.

bipedal: walking on 2 legs.

bird: a class of feathered, bipedal, endothermic, egg-laying vertebrates in the class Aves. Birds descended from maniraptoran theropod dinosaurs. 10,000 living species are known.

bird-of-paradise (botany) (aka crane flower (in South Africa)): a perennial angiosperm in the Strelitzia genus, with 5 species, native to South Africa.

bird-of-paradise (ornithology): a bird of the 42 species in 15 genera in the passerine family Paradisaeidae. Most species are endemic to Indonesia, eastern New Guinea, and eastern Australia. Males typically have ornate plumage which is employed in courtship displays.

Black Death: a plague in the 14th century caused by an airborne bacterium (Yersinia pestis).

Black Sea: a roughly oval, marginal sea of the Atlantic Ocean, situated between the Balkans, eastern Europe, the Caucasus, and western Asia, and supplied by several major rivers.

blind cavefish (aka Mexican tetra, AsTYAnax mexicanus): a sightless and eyeless freshwater fish native to the rivers of Texas and Mexico.

blood: an animal body fluid employed to transport nutrients to and waste products from cells.

bolide: a meteorite; a brighter-than-usual meteor; officially defined from a perspective on Earth as a fireball brighter than any of the planets.

Bølling oscillation (15–14.2 TYA): the interstadial period between the Oldest Dryas and Older Dryas stadials. Named after a peat sequence discovered at Bølling lake in central Jutland, the peninsula of Denmark. Sea level rose 100 meters from glacial melt during the Bølling oscillation. Temperate forests expanded.

bolus: a soft mass of chewed food.

bone: a rigid organ of connective tissue in vertebrates which forms a skeleton. Bone is mostly a fibrous matrix of composite material: inorganic calcium phosphate for rigidity and ossein (an elastic protein (collagen)) for fracture resistance.

bonobo (Pan paniscus): a peaceable ape, closely related to the chimpanzee and human species. Bonobos have a matriarchal society. Bonobos are notably fond of sexual behaviors.

booby: a seabird of 6–7 species in the Sula genus, closely related to gannets.

booklice (aka barklice or barkflies): an insect in the Psocoptera order, 1–10 mm long, that evolved during the Permian, 295–248 MYA. There are more than 5,500 extant species in 41 families. The name derives from their liking the paste formerly used in binding books. Booklice feed on algae and lichen found on trees.

Boquila trifoliolata: a woody vine capable of mimicking the leaves of the trees it climbs upon; endemic to southern Chile and Argentina.

Botomian (524–517 MYA): an age of the Early Cambrian epoch, ending with a major mass extinction event.

boundary (of tectonic plates): an intercourse between tectonic plates. A boundary is either divergent, convergent, or a transform fault. At a divergent boundary, plates move apart, increasing plate area. At a convergent boundary, plates come together, decreasing plate area, as part of one plate is subducted. At a transform boundary, 2 plates rub, in the same or opposite directions. Plate area is unchanged.

bovid: a cloven-footed ruminant ungulate in the Bovidae family, including antelopes, bison, African buffalo, water buffalo, (domestic) cattle, gazelles, goats, impala, muskoxen, sheep, and wildebeest. Bovids emerged 20 MYA.

bower: an architectural display intended to be attractive.

bowerbird: a medium-sized passerine, of which there are 20 extant species in the Pacific region. Male bowerbirds construct bowers to attract and seduce mates.

brachiopod: a marine animal with a hard valve (shell) on the upper and lower surfaces, unlike bivalve mollusks, which have a left-right shell arrangement.

brackish water: water with more salinity than fresh water, but not as salty as seawater.

Braconidae: a large family of parasitoid wasps, with 30,000–50,000 species.

brain: an animal organ central to nervous systems, located within the head.

bristlecone pine: 1 of 3 species of long-lived pine trees endemic to the western United States. The name derives from the prickles on female cones.

bronchus (plural: bronchi): an air passage into the lungs.

bronze: an alloy of copper (90%) and tin (10%).

Bronze Age (~3300–1300 bce): the middle period of the 3-age system, noted for the metallurgical production of bronze; the Stone Age preceded, the Iron Age followed.

brood parasitism: passing one’s own eggs off on another species to raise. Cuckoos and cowbirds are typical brood parasites.

brown anole (aka Bahaman anole, Anolis sagrei): a brown-to-blackish lizard native to Cuba and the Bahamas. The brown anole is aggressively invasive, feeding on arthropods and other lizards, including its cousin, the green anole. See green anole.

Brownian motion: the seeming random interactive motion of particles suspended in a fluid.

roworts, and liverworts are bryophytes.

bryozoan (aka moss animal): a phylum of aquatic invertebrates.

budding: a mother creating a smaller daughter. Baker’s yeast reproduces by budding.

bufflehead: a small sea duck in the goldeneyes genus (Bucephala). The name derives from the bird’s oddly bulbous head.

bulb: a plant food storage organ for dormancy.

bullroarer (aka rhombus, turndun): a weighted aerofoil (rectangular slat of wood) attached to a long cord. Swinging it in the air produces low-frequency sounds that travel long distances. Varying rotation and twist alter pitch. Origin unknown. A 17,000-year-old bullroarer was found in the Ukraine. The instrument is used by Australian aborigines.

burying beetle (aka sexton beetle): a beetle in the Nicrophorus genus which buries a small vertebrate as a larder for its larvae.

bushbaby (formally: galago): a small, slow-moving, nocturnal prosimian in the family Galagidae, native to continental Africa.

butane (C4H10): an alkane with 4 carbon atoms.

butterfly: a flying diurnal insect. There are 17,500 extant species of butterfly worldwide. Compare moth.

butterfly effect: a sensitive dependence on initial conditions, where an incremental change at one place in a nonlinear system creates a cascade that results in large changes.

buzz pollination (aka sonication): a technique by pollinating bees to release pollen by vibrating their bodies near the anther.

BYA: billions of years ago. by as an acronym for “billion years” is deprecated in modern geophysics, in favor of Ga, shorthand for gigaannum. Sometimes the old ways are the best.

Byzantine Empire (aka the Eastern Roman Empire) (330–1453): the predominantly Greek-speaking continuation of the eastern Roman Empire until annexed by the Ottomans in 1453. See Constantinople.


C3 plant: a plant that produces phosphoglyceric acid, with 3 carbon atoms, as its 1st-stage photosynthetic product. C3 plants are adapted to cool, wet environments. Compare C4, CAM.

C4 plant: a plant that produces oxaloacetic acid, with 4 carbon atoms, as its 1st-stage photosynthetic product. C4 plants are adapted to hot, sunny environments. Compare C3, CAM.

cactus (plural: cactuses or cacti): a spiny succulent perennial of over 2,000 species in ~175 genera.

Caenorhabditis elegans: a 1 mm long, transparent, unsegmented, roundworm (nematode) that lives non-parasitically in temperate soils.

calcium (Ca): the element with atomic number 20. Calcium is a soft, gray, alkaline, earth metal. Calcium plays vital roles in biochemistry and physiology. See calcium channel.

calcium carbonate (CaCO3) (aka calcite, calspar): one of the most common minerals on Earth, found in a vast variety of crystalline forms; a major constituent of limestone, chalk, and marble; the main component of exoskeletons and shells of marine organisms and snails, as well as eggshells. Lowering ocean acidity during the early Cambrian let organisms create calcium-carbonate protection, and thus leaving the 1st fossils.

calcium channel: a calcium ion (Ca2+) channel. Calcium channels are a ubiquitous cellular communication means.

calidrid (aka typical wader): a group of migratory wading birds.

callitrichid (Callitrichidae, aka Arctopitheci, Hapalidae): the family of arboreal New World monkeys that includes marmosets and tamarins.

CAM plant: a plant with a variation of the C4 pathway, using crassulacean acid metabolism (CAM) to fix atmospheric CO2. By minimizing photorespiration, CAM plants adapted to hot, dry environments. Most succulents are CAM plants. Compare C3, C4.

Cambrian (542–485 MYA): the 1st period of 6 in the Palaeozoic era, when the fossil record evidences a vast proliferation of complex life. The name derives from Latin for the area in Wales where the best Cambrian rocks in Britain are exposed.

camouflage: obscuring concealment through appearance and/or in/action.

canary: a small songbird in the finch family. Canaries were first bred in captivity in the 17th century; brought to Europe by Spanish sailors from west African islands (e.g., Canary Islands).

cancer: a disease characterized by uncontrolled cell growth.

candiru (aka cañero, toothpick fish, vampire fish, Vandellia cirrhosa): a hematophagic, parasitic, freshwater catfish, native to the Amazon basin.

cape gannet (Morus capensis): a large seabird, known for their elaborate greeting rituals at their nests.

capillary action: the ability of a liquid to readily flow when narrowly confined in a solid tube, essentially ignoring gravity.

capitalism: an economic system based upon private ownership of resources and their exploitation for exclusive profit.

Capitosauria: one of the 2 major clades of temnospondyl amphibians that survived the Permian–Triassic extinction event, the other being Trematosauria.

Capsaspora: a genus of amoeba which is a symbiont in the hemolymph of a Neotropical freshwater snail (Biomphalaria glabrate).

capybara (Hydrochoerus hydrochaeris): the largest extant rodent in the world; a gregarious native South American living near bodies of water.

carbon (C): the element with atomic number 6; an extremely friendly element, with 4 electrons available to form covalent bonds. Life is based upon molecules made with a carbon backbone.

carbon cycle: the gaseous cycling of carbon exchange among the geosphere (deep Earth), pedosphere (soil), hydrosphere (water bodies), atmosphere, and biosphere (living ecological systems).

carbon dioxide (CO2): a colorless gas that has fluctuated in concentration in Earth’s atmosphere through geologic time. Plants breathe CO2; animals exhale it. CO2 is a greenhouse gas.

carbon fixation (aka carbon assimilation): conversion of inorganic carbon (CO2) into organic carbon compounds.

carbonate: a salt or ester of carbonic acid (H2CO3), characterized by the presence of the carbonate ion CO2–3.

Carboniferous (359–299 MYA): the 5th period of 6 in the Palaeozoic era, following the Devonian period and preceding the Permian. Vast forests covered the land. Their demise produced the coal beds which came to characterize the geology of the period, and after which the period is named. Amphibians were dominant. Arthropods were quite common.

Carboniferous Rainforest Collapse (305 MYA): an abrupt extinction event that devastated tropical rainforests and decimated amphibians.

carboxylic acid: a polar molecule (–CO2H) connected to a hydrocarbon. A carboxylic acid completes itself with a side chain.

cardenolide (C23H34O2): a steroid produced by plants as a defense against herbivores.

cardiac glycoside: a toxic sugar that disrupts heart function.

caribou: see reindeer.

carotenoid: a tetraterpenoid organic pigment, naturally occurring in photosynthetic organelles of plants (e.g. chloroplasts).

carotid rete: a mesh of arteries that pass up the neck and supply blood to the head.

carrion beetle (aka burying beetle): a saprotrophic beetle.

carpel (aka pistil): the female part of a flower, acting as a pollen receptor.

carrying capacity: the (idea of a) maximum population size of a species given the constraints imposed by the environment.

caseid: an extinct family of synapsids. Caseids were the first fully terrestrial vertebrate herbivores. See edaphosaur.

Caspian Sea: an endorheic basin to the east of the Caucasus Mountains, between northern Europe and Asia; the world’s largest inland body of water, variously considered a lake or a full-fledged sea.

catabolism: the controlled cellular process (metabolic pathway) of breaking down organic matter to harvest energy via cellular respiration. Compare anabolism.

Çatalhöyük (aka Çatal Höyük): a Neolithic settlement in southern Anatolia 7500–5700 bce.

catastrophism: a theory that Earth has been episodically affected by sudden violent events. Contrast uniformitarianism.

category: a group of related concepts.

cattle egret (Bubulcus ibis): an egret with an affinity for cattle, from which it cleans ticks and flies as a dietary mainstay, with considerable tolerance by the client grazer.

Caucasus Mountains: a mountain system in the Caucasus region, stretching between the Black Sea and the Caspian Sea, intersecting Europe and Asia. Mount Elbrus, the highest peak in Europe, resides in the Caucasus Mountains.

cave hyena (aka Ice Age spotted hyena, Crocuta crocuta spelaea): a much larger (225 kg) cousin to the modern African hyena, which preyed on large mammals from Spain to northeastern China. The cave hyena went extinct 14–11 TYA, owing to climatic changes that reduced its prey while it was outcompeted by wolves and humans.

cave lion (aka Panthera leo spelaea): an extinct subspecies of lion that ranged over Eurasia, all the way to Alaska. The cave lion lived 370–2 TYA, though some put its extinction 14–12.5 TYA, during the last European (Würm) glaciation.

cecal valve: a chamber in iguana and some other lizards harboring vegetative gut flora.

cell (biology): the basic physical unit of an organism.

cell signaling: a protocol for cellular communication, whether intracellular or intercellular.

cell wall: a flexible membrane holding the contents of the cell and providing an interface to the outside environment.

Cenomanian (100.5–94 MYA): the oldest age of the Late Cretaceous period.

Cenozoic (65.5 MYA–now): the geological era from the demise of the dinosaurs to present day.

centipede: an arthropod with an awful lot of legs; a metameric animal with a pair of legs for each body segment. Of the estimated 8,000 species, leg pairs vary from under 20 to over 300, but always an odd number (e.g., 15 or 17 pairs), never even.

cephalopod: a class of marine animals in the mollusk phylum. Squid, octopuses, cuttlefish, and nautilus are among the over 800 extant species of cephalopods.

Ceratopsia (aka Ceratopia): a group of herbivorous, beaked dinosaurs that thrived during the Cretaceous.

Cetacea: a clade of aquatic mammals of ~89 species, commonly called whales, dolphins, and porpoises. Most cetacean species prefer colder waters. Cetaceans are adapted to stay under water for extended periods: 7 to 30 minutes – much longer than most other mammals.

chameleon: a distinctive and highly specialized clade of Old World lizards, with over 200 species. Many chameleons can change color at will.

chamois (Rupicapra rupicapra): a goat-antelope of 2 species, endemic to the mountains of Europe.

chaperone (molecular biology): a protein that assists another protein (or other macromolecular structure) in folding or unfolding. Many chaperone facilitate stress tolerance, especially thermal shock.

chaparral: a shrubland plant community found primarily in California and the northern part of Baja California.

characid (aka characin): tropical and subtropical freshwater fish in the Characidae family, native to the Americas.

chelonian: a turtle.

cheloniology: the study of turtles.

chemical species: atoms or molecules that are energetically equivalent.

chemistry: the science of matter, especially chemical reactions.

chemoreception: reception of a chemical signal.

chemosynthesis: employing chemical reactions to generate usable energy.

chert: a sedimentary silica-rich rock essentially comprising microcrystalline quartz.

chick: a young bird.

Chicxulub: site of a 66 million-year-old impact crater underneath the Yucatán Peninsula in Mexico.

chimeric: an organism of diverse genomic constitution.

chimpanzee (Pan troglodytes): a medium-sized ape, closely related to bonobos and humans.

chitin ((C8H13O5N)n): a long-chain polysaccharide that includes proteins, lipids, and catecholamine. Chitin serves as the main component of the cell walls of fungi, the exoskeletons of animals such as insects and arthropods, and the beaks of cephalopods, including octopi and squid. Compare keratin. Also see lignin.

chiton (aka sea cradle, loricate, polyplacophoran): a marine mollusk that arose 500 MYA. Found worldwide, there are ~940 extant species and 430 known fossil species.

chlorophyll: the green biomolecule in cyanobacteria and the chloroplasts of algae and plants that absorbs light for photosynthesis. See cryptochrome, neochrome, phototropin, phytochrome.

chloroplast: the photosynthetic plastid in algae and plant cells.

chloroplast capture: obtaining the genome of another plant by uptake of an organelle.

choanoflagellate: a flagellate eukaryote which lives as independent single cells or in rosette-shaped colonies. Choanoflagellates are considered the closest living relatives of metazoa.

chordate: an animal in one of the following groups: fish, amphibian, reptile, bird, tunicate, lancelet, or mammal; an animal with tadpole characteristics (a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail) during some period of its life cycle; a member of the phylum Chordata.

chromatin: the combined package of proteins and DNA that comprise physical genetic information storage in the nucleus of a eukaryotic cell.

chromophore: the moiety that causes a conformational change of a photosensitive molecule when hit by light.

chromosomal crossover: exchange of genetic material between homologous chromosomes.

chromosome: an elaborately coiled molecular package of genetic material in a eukaryotic cell, comprising DNA genes, regulatory elements such as histones, and other nucleotide sequences. Compare genophore.

cicada: a flying insect of 3,000+ species in the Cicadoidea family. Cicada live most of their life underground, coming to the surface as adults to make a racket and mate for a few weeks or months. Individually defenseless, cicada numerically overwhelm predators by emerging en masse; a phenomenon called predator satiation.

cichlid: a freshwater fish in the large, diverse family Cichlidae, with ~3,000 species. The most varied speciation occurs in Africa and South America. All cichlids practice parental care for their eggs and fry.

ciliate: a group of protozoans characterized by cilia.

cilium (plural: cilia): a slender protuberance projecting from a cell, capable of undulating wave motion.

civilization: a culture which characterizes a society.

clade: a group of biological taxa, such as genus, which includes all descendants of a common ancestor.

cladism (evolutionary biology): (aka phylogenetic nomenclature, cladistics): biological classification based upon clade, reliant upon branching.

Cladocera (aka water flea): an order of tiny crustaceans (0.2–6.0 mm).

clasper: a male animal anatomical structure used in mating. Male cartilaginous fish, such as sharks, have claspers formed from the posterior portion of their pelvic fin.

class (biological classification): the taxon above order and below phylum. Though the taxon was introduced by Joseph de Tournefort in 1694, botanists nowadays typically don’t use class. See family.

clastic rock: a fragment (clast) of a larger rock.

clathrate hydrate: a crystalline lattice of water molecules storing trapped gas.

climate: a characterization of tropospheric activity in an area over ~30 years, accounting for seasonal variations. The standard of 30 years is often adjusted to suit reportage. Compare weather.

cloaca: a posterior opening that serves as the only opening for urinary, intestinal, and reproductive tracts of certain animal species, including amphibians, birds, reptiles, and monotremes.

cloud: a visible mass of liquid droplets or frozen crystals, each particle being 1–1,000 micrometers in diameter.

clupeid: a ray-finned fish in the Clupeidae family, including herrings, sardines, shads, ilish, and menhadens. Clupeids are mostly marine forage fish.

clutch: a group of laid eggs.

Cnidaria: a phylum of early-evolved jelly-like aquatic animals which includes jellyfish and anthozoa. There are now over 10,000 species. The distinguishing feature of cnidarians is cnidocytes. Cnidarian bodies are made of mesoglea. Jellyfish are exemplary cnidara, though coral too are cnidarians. Compare Ctenophora. See Coelenterata.

cnidocyte (aka cnidoblast, nematocyte): an explosive cell containing 1 giant secretory organelle (cnida). Cnidae are used to capture prey and defend against predation.

coal: a combustible sedimentary rock formed from decayed vegetative matter by heat and pressure. Compare petroleum.

coastal dung beetle (Onthophagus nigriventris): a dung beetle native to Africa.

cockroach coconut (genus: Cocus): a large tree in the palm family, found in the tropics globally. The coconut originated in the India-Indonesia region over 55 MYA, with its robust seeds making their way around the world by riding ocean currents.

cod (aka codfish, true cod): a generally medium-sized marine fish in the Gadidae family, distinguished by 3 dorsal fins and 2 anal fins. Cod are highly prolific, producing millions of eggs for each spawning.

coevolution: intertwined adaptation among species, inspired by their interaction.

cofactor: a molecule that binds to a protein to have the protein perform a task. Enzymes are typically activated by cofactors, which essentially act as helper molecules. The molecule may either be an inorganic ion or organic (coenzyme).

cognition: the process of understanding, involving both awareness and judgment.

coherence: the intelligent interaction behind Nature. Like Ĉonsciousness, coherence localizes.

collagen: the main structural protein in the extracellular space of various connective tissues in animals. Collagen comes in the form of elongated fibrils.

coleoid: the group of cephalopods that includes squid, cuttlefish, and octopi. Their sister group, the nautiloids, have a rigid outer shell for protection. In contrast, coleoids have at most an internal shell, bone or cartilage used for buoyancy or support.

collar (botany): the thin band of tissue where a grass leaf meets the sheath.

colony: a population of tolerant individuals.

comb jelly (aka ctenophore): a gelatinous marine animal in the phylum Ctenophora that arose early in the history of life, with a worldwide presence. Comb jellies are the largest animals that swim via groups of cilia. Almost all comb jellies are predators, with prey ranging from microbial larvae to small adult crustaceans.

comet: a ball of ice and dust originating in the Oort cloud, in the outer reaches of the solar system.

commensalism: a relationship of between 2 organisms where one benefits without affecting the other.

common cordgrass (Spartina anglica): a quick-growing sturdy grass that forms large, often dense colonies on coastal salt marshes. Many species of cordgrass will hybridize if the opportunity arises.

common lizard (Zootoca vivipara): a viviparous lizard common throughout much of Eurasia, though some populations re-evolved oviparity.

communication: emitted ecological information by an organism.

communication substitution: signaling in a way that relies upon a strong innate preexisting reception.

competitive exclusion: the dynamic where competition for the same resource by 2 species progresses to dominance by one species.

compound (chemistry): a combination of elements bonded into a molecule.

concept (aka idea): an abstract construct involving discriminatory categorization.

conceptualization: the mental process of resolving sensations into concepts.

condor (aka New World vulture): a scavenging bird native to the Americas.

Confuciusornis: a crow-sized bird that appeared 130 MYA.

conifer: a woody cone-bearing seed plant. Most conifers are trees, with a few shrubs. Conifers dominate the forests in the northern hemisphere.

conjugation (microbes, particularly bacteria): a term used for horizontal gene transfer (HGT) by researchers in 1946, who analogized the HGT process to sex.

consciousness: an individual platform for awareness. All life constituents require awareness, including proteins, cells, and organisms. Compare Ĉonsciousness.

Ĉonsciousness: the unified field of consciousness. Ĉonsciousness naturally localizes into individualized consciousnesses. Compare consciousness.

conservation (evolutionary genetics): preservation of a trait through generations (of cells or offspring).

conspecific: of the same species. Contrast interspecific.

Constantinople: the capital city of the Byzantine Empire. Originally named Byzantium upon its founding in the 7th century bce, it became Constantinople in 330. During the 12th century, Constantinople was the largest and wealthiest European city. See Byzantine Empire.

Although besieged on numerous occasions, Constantinople fared well owing to its massive defenses, most notably its double wall facing land, and being built on 7 hills. The city was only taken in 1204 by the army that was the 4th Crusade, whose original mandate was to conquer Muslim-controlled Jerusalem. The Crusades were a series of organized pillages sponsored by the Roman Catholic Church.

Constantinople fell to Ottoman sultan Mehmed II in 1453. Its name ostensibly changed to Istanbul; thus began the Ottoman Empire.

constructal law: the tenet that the design and evolution of all forms aim to facilitate flow; a patterning mechanism for gyres. See Spokes 1 for a fuller explanation.

consumer (biology) (aka heterotroph): an organism unable to sustain itself by inorganic means. Animals are consumers. Contrast producer.

continent: a gigantic landmass, 7 of which are currently extant on Earth: Africa, Antarctica, Asia, Australia Europe, North America, and South America.

continental drift: the movement of tectonic plates that causes continental masses to move about.

convection: the concerted, collective movement of fluids (liquids, gases) and rheids (a solid deformed by viscous flow).

convergent boundary: a boundary where tectonic plates come together, with one plate subducting under another. Contrast divergent, transform.

convergent evolution (aka parallel evolution): the independent evolution of similar traits in organisms of separate species which are usually not closely related.

Cooksonia: an early land plant that evolved vascular water transport.

copepod: a group of tiny (1–2 mm) crustaceans that live in the sea and nearly every freshwater habitat. 13,000 species are known; 2,800 are freshwater dwellers.

copper (Cu): the element with atomic number 29; a soft, malleable, and ductile metal, with very high thermal and electrical conductivity.

copper shark (aka narrowtooth shark, bronze whaler): a species of requiem shark, the only species of its genus that favors temperate latitudes. Copper sharks are found in brackish estuaries and rivers, shallow bays, and offshore waters to 100 meters or more.

Coptic: an alphabet and language used by the Egyptians from the 1st century ce into the 13th century.

coral: a colonial marine invertebrate comprising numerous identical polyps.

cormorant (aka shag): a medium-to-large coastal, aquatic, piscivorous bird of ~40 species, native to Eurasia, parts of Africa, North America, Australia, and New Zealand. Most are seabirds, though some cormorants ply inland waters. Cormorants are excellent divers. The classification of cormorants is contentious.

cortisol (C21H30O5): an animal glucocorticoid (steroid hormone) released when blood sugar is low or in response to stress. Cortisol increases blood sugar level, aids metabolism, reduces inflammation, decreases bone formation, and suppresses the immune system. More generally, cortisol readies the body to react against a stressful situation. Prolonged high cortisol level from chronic stress weakens and ages the body.

corvid: a cosmopolitan bird family (the crow family) of over 120 species, including choughs, crows, jackdaws, jays, magpies, nutcrackers, ravens, rooks, and treepies.

cosmic rays: radiation from outer space.

cosmopolitan (biogeography): a taxon with species in a broad range of biomes.

cosmotrophic: an organism that can survive in space.

cotyledon: an embryonic leaf in a plant seed. See dicot, monocot.

cowbird: an insectivorous New World brood parasitic passerine of 5 species in the Molothrus genus.

coywolf: a coyote/wolf/dog combination.

craton: the stable part of a continental plate, generally in the interior, built upon basement rock.

creationism: the Christian belief that the universe and life were specific acts of divine creation. Creationism and organic evolution are antithetic.

crepuscular (biology): an animal active primarily during twilight (dawn and dusk), as contrasted to diurnal or nocturnal. As a legacy from their time underfoot of dinosaurs, many mammals are crepuscular, as are most moths, many beetles and flies, and some birds. For temperature reasons, desert squamates tend to be crepuscular.

Cretaceous (145–66 MYA): the 3rd and last period in the Mesozoic era, following the Jurassic and preceding the Paleogene. The name derives from the Latin for chalk, and is abbreviated as K. The Cretaceous ended with the major mass extinction event that killed all non-avian dinosaurs.

Crete: the 5th-largest island in the Mediterranean Sea and the largest Greek island.

cricket (aka true cricket): an insect with a somewhat flattened body and long antennae. 900 cricket species are known. Crickets are related to katydids; more distantly related to grasshoppers, with which they are often confused.

crinoid: an echinoderm characterized by a mouth on its top surface surrounded by feeding arms. Sea lilies and feather stars are crinoids. There are 600 extant species: a considerable reduction from earlier geological periods.

crocodile: a large, semiaquatic reptile which first evolved 83.5 MYA. Birds are their closest living relative.

Cro-Magnon (aka European early modern human): European human contemporaries of Neanderthals.

Cromwell Current (aka Pacific Equatorial Undercurrent): an eastward-flowing subsurface current that runs the length of the equator in the Pacific Ocean; named after its 1952 discoverer, Townsend Cromwell.

crow: a clever corvid in the Corvus genus, known for their mischievous ways. 40 species are known.

crust (geology): the outermost solid slab of a rocky planet.

crustacean: a large group of arthropods, including barnacles, krill, crabs, crayfish, shrimp, and lobster. There are at least 67,000 species, from 0.1 mm to 3.8 meters in size. Most crustaceans are aquatic, but some, such as woodlice, are terrestrial.

Cryogenian (720–635 MYA): the middle period of 3 in the Neoproterozoic era, following the Tonian and preceding the Ediacaran. A period of global glaciation (Snowball Earth), to which the name refers.

crypsis: the ability of an organism to avoid detection or observation. Contrast aposematism.

cryptochrome: a photoreceptive protein sensitive to blue light, found in both plants and animals. Cryptochrome is employed for circadian rhythms and sensing magnetic fields. See chlorophyll, neochrome, phototropin, phytochrome.

Cryptodira: a suborder of the turtle order (Testiudines) that includes most extant tortoises and turtles. Cryptodires lower their necks and pull their heads straight back into their shells. Contrast Pleurodira.

crystallin: a transparent, water-soluble structural protein in the cornea and lens of vertebrate eyes. One function of crystallins in the lens is to optimize the refractive index.

Ctenophora: a phylum of marine animals that use groups of cilia for swimming, such as comb jellies. Ctenophores have soft, gelatinous bodies. Compare Cnidaria. See Coelenterata.

cuckoo: a near passerine with distribution ranging across all continents except Antarctica. A large minority of cuckoos practice brood parasitism.

culture (biology): the transfer of knowledge among conspecifics, and from one generation to the next.

culture (microbiology): a colony of microbes.

culture (sociology): a system of shared abstractions, beliefs, and/or rituals among a tribe of humans. Culture represents common symbolic expression in a social context.

cuticle: a multi-layered shell or structure on the outside of many invertebrates, employed as an exoskeleton. The main ingredient in a cuticle is chitin. Cuticle also refers to protective layers of organisms in other kingdoms, including fungi and plants.

cuticular hydrocarbon: a gaseous hydrocarbon exuded from the cuticle of an organism, typically an insect.

cuttlefish (aka cuttles): a marine cephalopod. Cuttlefish have a unique internal shell: a cuttlebone. Cuttlefish are mollusks, not fish.

cyanobacteria: photosynthetic bacteria; often called blue-green algae, though they are not in the same group as algae.

cyanophage: a virus that infects cyanobacteria.

cycad: a gymnosperm with a stout, woody trunk and a crown of large, stiff evergreen leaves. Cycads vary in size from a few centimeters to several meters. Cycads typically grow very slowly, with longevity: over 1,000 years.

cyclical parthenogensis: a reproductive system in which organisms nominally asexually produce clones, but with occasional sexual reproduction.

cycloalkane: a hydrocarbon with 1 or more rings of carbon atoms.

cynodont: a clade (Cynodontia) of carnivorous therapsids that arose 260 MYA, eventuating in mammals.

Cyprus: the 3rd-largest island in the Mediterranean Sea.

cytokinesis: the process by which the cytoplasm of a eukaryotic cell divides.

cytology: the study of living cells.

cytolysis (osmotic lysis): an osmotic (water) imbalance from excess water inside a cell, causing the cell to burst.

cytoplasm: the watery gel that holds a cell’s organelles within a plasma membrane.

cytosine (C) (C4H5N3O): a nucleobase of DNA and RNA. Cytosine is complementary to guanine. Cytosine is inherently unstable and can spontaneously change into uracil (spontaneous deamination). If not repaired, spontaneous deamination results in a point mutation.

cytoskeleton: filaments of protein within a cell, providing cellular scaffolding.


Dakotarapator: a species of large carnivorous dromaeosaurid endemic to North America.

damselfish: a ~250-species family of mostly marine fish, though a few live in freshwater rivers. Many damselfish species reside among tropical coral reefs. Damselfish are deep-bodied and usually have forked tails. Many are brightly colored. Damselfish are lively, quick, and are typically aggressively territorial.

dandelion: an herbaceous plant in the genus Taraxacum with 60 to over 2,000 species, native to Eurasia and North America. (Botanists do not concur on dandelion speciation, hence the wide speciation range.)

Dark Ages: the 5th–10th centuries in Europe; the early Middle Ages, following the decline of the Western Roman Empire. Coined by Francesco Petrarch in the 1330s, when writing of the previous historical period: “Amidst the errors there shone forth men of genius; no less keen were their eyes, although they were surrounded by darkness and dense gloom.” The term Dark Ages is generally disparaged by contemporary historians, owing to its critical overtone; yet the aptness of its cultural attribution cannot be denied.

Darwinism (aka natural selection): the disproven hypothesis of Charles Darwin that evolution transpires only over millions of years by random rearrangements of matter that create species which endure or are eliminated via competition with other species (“natural selection” via “survival of the fittest”).

Natural Selection almost inevitably cause much Extinction of the less improved forms of life. ~ Charles Darwin

daughter cell: a cell formed from a parent cell.

de novo: anew.

Decapoda: an order of crustaceans comprising crayfish, crabs, lobsters, prawns, and shrimp, with ~2,700 genera and nearly 15,000 extant species. 3,300 extinct species are known. Most decapods are scavengers. Decapods arose during the Devonian.

Deccan Traps: an extensive igneous province in west-central India, on the Deccan Plateau; one of the largest volcanic formations on Earth. The term trap has been used since the late 18th century for rock formations that make step-like hills; derived from the Scandinavian word for stairs (trappa).

deception: the act of presenting a false impression.

deciduous: a tree or shrub that loses its leaves seasonally. The term is also used with animals, for parts that are seasonally or developmentally lost, such as deer antlers and baby teeth.

decision theory: (statistics): quantitative methods for reaching optimal decisions for defined problems. Decision theory is related to game theory.

decomposer: see saprovore.

deep homology: the concept that growth and cell differentiation are governed by genetics which are homologous and deeply conserved across much of life.

deer: an even-toed ungulate ruminant in the Cervidae family.

dehiscent (botany): the natural bursting open of capsules, such as anthers or fruits, for the discharge of their contents.

deletion (genetics): a mutation via deleting one or more nucleotides. Contrast insertion.

Denisovan (500–30 TYA): a Homo species or subspecies, based upon remains found in Denisova Cave in the Altai Mountains of Siberia.

dentary: see mandible.

denticle: a conical pointed projection (as a small tooth).

descent (evolutionary biology): evolution from; derivation from an ancestor; lineage.

Descent of Man, The, (1871): the 2nd book about evolution by Charles Darwin, focused on human evolution and sexual selection, after On the Origin of Species (1859).

determinism: belief in cause and effect, from which emanates the doctrine that all facts and events exemplify natural laws.

detrivore: see saprovore.

devolution (evolutionary biology) (aka de-evolution, backward evolution): the idea that a species can revert to a supposedly more primitive trait.

Devonian (416–359 MYA): the 4th of 6 periods in the Palaeozoic era, following the Silurian and preceding the Carboniferous. The Devonian experienced the first radiation of terrestrial life. The name derives from Devon, England, where rocks of the period were first studied.

diapsid: a reptile with 2 holes on each side of its skull. Diapsids arose 300 MYA. All lizards, crocodiles, snakes, turtles, and tuatara are diapsids.

diatom: an alga; one of the most common phytoplankton.

dichromacy: having 2 types of color vision receptors. Dichromats typically see in the blue-green color spectrum but cannot detect red. Dichromats can distinguish 10,000 distinct colors. Most mammals are dichromats. Compare monochromacy, trichromacy, tetrachromacy.

dicot (dicotyledon): a plant with 2 embryonic leaves (cotyledons) in its seed. Compare monocot.

Dickinsonia: a genus of marine Ediacaran biota, possibly an animal.

dicynodont: a beaked herbivorous mammal-like reptilian synapsid that evolved during the Middle Permian, successfully radiated during the Late Permian, and lived through Triassic.

diet: habitual nourishment.

diffusion (chemistry): the passage of molecules between chemical species.

dimethyl sulfide (C2H6S) (DMS, aka methylthiomethane): an organosulfur compound that is a breakdown product of dimethylsulfoniopropionate and is also produced by bacterial metabolism of methanethiol.

dimethylsulfoniopropionate (DMSP: (CH3)2S+CH2CH2COO): an organosulfur compound that acts as an osmolyte.

Dimetrodon: an extinct genus of carnivorous synapsid, likely one of the top predators during the early Permian.

dimorphism: the existence of 2 different forms; typically refers to a size difference between sexes.

Dinofelis: a genus of extinct, jaguar-sized, saber-toothed cats.

dinosaur: a diverse clade of largely extinct reptiles, excepting birds; an arbitrary exclusion, as birds descended from dinosaurs.

diploid: an organism having 2 sets of chromosomes. Most eukaryotes are diploid: 2 sets, one from each parent, typically through sexual reproduction. Humans are diploid.

dirt: see soil.

dispersal (evolution): speciation when a subpopulation migrates outside the range of the main population, adapting to a new species over time. Compare vicariance.

disruptive coloration (aka disruptive camouflage, disruptive patterning): camouflage that works by breaking up the appearance of outlines which help sense shape. Contrast aposematism.

dissolved organic matter (DOM): the slowly sinking remains of oceanic life.

dissonance: divergence between signal and reception.

diuretic: something that tends to increase the production of urine.

diurnal (biology): active during the day. Contrast nocturnal. See crepuscular.

diurnal temperature variation: the temperature extremes between night and day.

divergence (evolutionary biology): variation within a population that leads to speciation.

divergent boundary: a boundary where tectonic plates move apart. Contrast convergent, transform.

diversity loss: a measure of the number of species lost during an extinction event.

Dmanisi, Georgia: a site where 5 divergent hominin fossils were found; earliest evidence of hominin toothpick use.

DMSP: see dimethylsulfoniopropionate.

DNA (deoxyribonucleic acid (C5H10O4)): a long, double-stranded molecular chain employed as a physical template for biochemical production. DNA is physically heritable. There is no reasonable explanation based upon known facts that the information essential for trait inheritance is portered by DNA; quite the contrary: DNA itself cannot possibly be the energetic agent of heredity. See RNA.

dodo: a meter-tall flightless bird, hunted to extinction (1598–1662) on its native Indian Ocean island of Mauritius when the Dutch first populated the island. The Dutch left Mauritius in 1710. By then most of the large terrestrial vertebrates there had been killed off. The dodo’s extinction went unrecognized until the 19th century, when it briefly captured the public imagination, spawning the common quip of extinction: “dead as a dodo.”

dog: a subspecies of the gray wolf, domesticated ~40 TYA. A ubiquitously popular pet owing to affectionate communication and obedience, there are ~525 million dogs worldwide.

Dollo’s law: the 1893 declaration by Louis Dollo that evolution is irreversible: a one-way vector. Dollo’s law is false, as there are many examples of devolution.

dolphin: a marine mammal closely related to porpoises and whales (altogether: Cetacea). There are ~40 species of dolphin, varying in size from 1.2 m and 40 kg (Maui’s dolphin) to 9.5 m and 10 tonnes (orca). Dolphins are demonstrably clever, typically gregarious, and playful.

domain (biological classification) (aka empire): the 2nd-highest taxon (below life), with 3 classes: archaea, bacteria, and viruses.

dominant (trait): a genetic trait (allele) that masks a recessive trait.

dominion: the power of environmental control. Most commonly a political term for sovereign authority.

Doppler shift: a change in frequency of a wave relative to a perceiver.

dormancy: a state of inactivity (dormant).

dorsal: the back or upper side (of an organism). Contrast ventral.

double fertilization: the seed-producing process in angiosperms where the embryo and endosperm are separately fertilized.

dragonfly: an exceedingly successful, flying, insect predator.

drake: a male duck. A female duck is called a duck or hen. Baby ducks are ducklings. Only hens quack. Drakes have a softer whistle.

Dromaeosauridae: a family of feathered theropods.

Dryopithecus: a genus of extinct arboreal ape that lived in Africa and Eurasia during the Late Miocene, ~12.5 MYA.

duck: an aquatic bird in the Anatidae family.


E. (Escherichia) coli: a rod-shaped enterobacteria commonly found in the lower intestine of endothermic organisms. E. coli normally colonize an infant’s gut within 40 hours of birth, delivered by food, water, or mere handling. E. coli has long been a model organism in microbiology studies; one of the first organisms to have its entire genome sequenced, in 1977.

early modern humans (EMH): humans of the Upper Paleolithic.

Earth: the 3rd planet from the Sun; the densest and 5th-largest.

ecdysis: the molting of cuticula (outer skin) in many invertebrates, including insects.

echinoderm: a phylum of marine invertebrates comprising 7,000 species, including sea stars, sea urchins, sand dollars, and sea cucumbers. Echinoderms live at every ocean depth.

echolocation (aka biosonar): rapid series of ultrasonic clicks that form mental images from received echoes of nearby objects.

ecology: an interactive interface; patterns of relations among entities; as a subdiscipline of biology, patterns of interrelations between life forms (e.g., cells, organisms) and their environment (including other organisms); more broadly, the relations between bioelements.

economics: the activities of production, distribution, and consumption of goods and services, and of the material well-being of humans; also, the study thereof.

ecosystem: the community of biota in a biome, and the abiotic (non-living) elements within the area.

ectotherm: an animal without internal means to maintain thermal homeostasis. Ectothermic animals, such as reptiles, practice behaviors to regulate body temperature, like lying in the sun to warm oneself. Commonly misnamed cold-blooded, ectotherms’ blood is just as warm as endotherms. Compare endotherm. See mesotherm.

ED: extra dimensions (or extra-dimensionality); the spatial dimensions of existence beyond the 3 that are perceptible and measurable. See 4D and HD.

edaphosaur: a family of large herbivorous synapsids. See caseid.

edentulism: evolutionary loss of teeth.

Ediacaran (635–542 MYA): the 3rd and last period of the Neoproterozoic era, preceding the Cambrian period. The name derives from the Ediacara Hills in Australia, where the first fossils of the period were found by Reg Sprigg in 1946.

egene: (the idea of) an energetic hereditary unit which conveys all the information needed to create a trait or biological effect. Nucleic acids alone cannot explain heredity. Compare gene.

egg: an organic vessel in which an embryo first begins development. See sperm.

egret: a white or buff colored bird, often preferring watery areas, practically synonymous with heron.

Egyptian (civilization) (3150–30 bce): an ancient civilization in Northeastern Africa, concentrated along the lower Nile River.

El Niño: an anomalous band of warm ocean water that periodically develops off the Pacific coast of South America.

elapid: a family of ~300 species of venomous snakes, characterized by short fangs fixed at the front of the upper jaw.

Elasmosaurus: a genus of extremely long-necked plesiosaur that lived during the Late Cretaceous.

electric dipole moment (EDM): a measure of electrical polarity, by measure of the separation between negative and positive charges.

electric fish: a fish that can generate an electric field (electrogenic). Fish that can detect electric fields are electroreceptive. Most electric fish are also electroreceptive. Electric fish are found in the sea and in freshwater rivers of South America and Africa. Sharks, rays, and catfishes are electroreceptive, but cannot generate an electric field.

elephant: a large mammal native to Africa and India. There were once over 350 elephant species; now there are only 2.

elephant seal: a large oceangoing seal. Elephant seals spend 80% of their lives in the ocean. They can hold their breath for longer (100 minutes) and dive deeper (1,550 meters) than any other noncetacean mammal.

elytron (plural: elytra; aka shard): the hardened forewing of beetles and a few true bugs.

embryo: an early stage of development in multicellular diploid eukaryotes.

embryogenesis: the process by which an embryo forms and develops.

embryology: the branch of biology interested in the origination and development of embryos and fetuses.

embryophyte: a land plant, including mosses, liverworts, ferns, other seedless plants (pteridophytes), gymnosperms, and angiosperms.

empiricism (epistemology): the presumption that knowledge derives solely from sensory experience.

empiricism (philosophy of science): the belief that Nature may be entirely explained by physical forces.

emu (Dromaius novaehollandiae): the largest Australian bird and 2nd only to the ostrich. Like ostriches, emu are flightless. Emu have incredibly strong legs.

endemic: restricted to a circumscribed environment or area, such as an island. Compare indigenous, native.

endocarp: the inner layer of a pericarp when a fruit has 2 or more layers.

endocrine: a secretion from a gland into the circulatory system. Many endocrines are hormones.

endocrine gland: a gland that secretes a hormone directly into the bloodstream to regulate a body function. Exemplary endocrine glands include adrenal, pineal, hypothalamus, pituitary, and thyroid, along with various glands for the digestive system (stomach, duodenum, liver, kidney, pancreas), and reproductive system (ovary, testes, uterus, placenta (when pregnant)). Compare exocrine gland.

endocrine signaling: intercellular communication over a long distance. Compare paracrine signaling, juxtacrine signaling.

endocytosis: the cellular process of absorbing macromolecules, such as proteins, by engulfing them. All cells employ endocytosis. Contrast exocytosis.

endogenous retrovirus (ERV): a transposable element that resembles a retrovirus.

endolith: an organism that lives sheltered inside rock, coral, or animal shell.

endoplasmic reticulum (ER): an organelle connected to the nuclear membrane; a membranous network of sac-like structures (cisternae) held together by the cytoskeleton. ER serves various functions, including carbohydrate metabolism, lipid synthesis, glycoprotein production, and cell membrane manufacture. ER also plays a critical role in assisting mitochondrial division and replication.

endorheic basin: a closed drainage basin: no outflow to another body of water.

endoskeleton: an internal animal support structure composed of mineralized tissue, such as bone. Vertebrates have an endoskeleton. Contrast exoskeleton.

endosperm: the tissue inside an angiosperm seed that provides nutrition to a growing embryo until it can establish roots.

endostyle: an organ in chordates used in filter-feeding.

endosymbiont: an organism living within the body or cells of another organism, forming a mutually advantageous arrangement.

endotherm: an animal species with internal means to maintain thermal homeostasis. Birds and mammals are endotherms. Endothermy raises an animal’s metabolic needs compared to ectothermic animals. Compare ectotherm. See mesotherm.

energy (physics): the idea of an immaterial force acting upon or producing matter. Energy is characterized relatively and by type (how it affects matter). Energy manifests only through its effect on matter. Though the foundational construct of existence, energy itself does not exist. As matter is made of energy, this fact tidily proves energyism.

energyism (aka (philosophical) immaterialism): the monistic doctrine that Nature is a figment of the mind. Energyism differentiates between actuality and reality. Whereas actuality is phenomenal, reality has a noumenal substrate, emergently spawning a shared actuality (showtivity) via a unified Ĉonsciousness. Contrast matterism.

engineering: the practical application of science. See technology.

entelechy: an Aristotelian notion of a vital force for living organisms.

entanglement (physics): distinct phenomena behaving synchronously. Entanglement defies locality.

enterobacteria: a large family of bacteria that make their living inside eukaryotes, either symbiotically or as a pathogen.

entropy: the tendency of energy to dissipate and equilibrate (dissipate to equilibrium); the natural physical tendency toward disorder.

environment: a designated spatial region or conceptual realm.

envirotype: the ecological influences on an organism and typical organism interactions with the environment.

enzyme: a protein which acts as a biological catalyst.

Eocene (56–33.9 MYA): the middle epoch of the Paleogene period. The term refers to the emergence of modern animals that appeared during the epoch. The Eocene ended with the Grande Coupure mass extinction event.

eocyte (aka Crenarchaeota (Greek for “spring old quality”)): a sulfur-loving anaerobic marine thermophile.

Eodromaeus (~232 MYA): an early saurischian dinosaur.

eon (geology): a duration in the geological time scale, half a billion years or more; longer than an era.

Eoraptor (~231 MYA): one of the earliest dinosaurs, a herrerasaurid.

epeiric: a shallow inland sea that covers central areas of continents during periods of high sea level.

Ephedra: an evolutionarily isolated genus of low, straggling, or climbing gymnospermous desert shrubs.

epigenetic: a gene regulation mechanism without changing the structure of the gene involved (i.e., without genetic mutation).

epigenesis: the process of producing primordial germ cells via extracellular signals. Contrast preformation.

epigenome: the conceptual sum of instructions in a cell affecting access and expression of genes.

epiphyte: a plant that non-parasitically grows on the surface of another plant, deriving its water and nutrients from the surrounding environment.

epoch (geology): a duration in the geological time scale, tens of millions of years; shorter than a period, longer than an age.

equid: an odd-toed (perissodactyl) ungulate in the Equidae family, with horses, asses, and zebras extant.

era (geology): a duration in the geological time scale, several hundred million years; shorter than an eon, longer than a period.

erythrocyte (aka red blood cell): a vertebrate blood cell that transports oxygen.

Erythropsidinium: a genus of dinoflagellate algae, some species of which have an organelle eye capable of seeing polarized light and thereby hunting prey.

Escherichia coli: see E. coli.

essential amino acid: an amino acid necessary for health that cannot be synthesized by the human body, and so must be obtained via diet.

ester: an organic compound comprising a carbonyl adjacent to an ether.

estuary: a partly enclosed coastal body of water connected to the sea which has at least 1 river or stream flowing into it.

ether: a class of organic compounds characterized by an oxygen atom bonded to 2 carbon atoms (C-O-C).

ethology: the study of animal behavior, often with an eye toward evolutionary implications.

ethylene (C2H4 or H2C=CH2): a hydrocarbon; the simplest alkene. Ethylene hastens fruit ripening and floral senescence.

Etruscan civilization (8th–4th century bce): the powerful and wealthy civilization in western central and northern Italy prior to its assimilation into the Roman Republic.

eudicot: an evolutionary advance of dicots that arose 115 MYA and numerically became the dominant dicot form.

eukaryote: an organism with internal cell structures (organelles). All multicellular life is eukaryotic. See prokaryote.

Euparkeria (245–230 MYA): a reptilian genus that presaged dinosaurs.

euphotic zone: a layer of water with sufficient sunlight for photosynthesis.

euphorbia: a tropical plant in the genus Euphorbiaceae.

eusocial: an animal that has: 1) overlapping generations, 2) cooperative care of the young, and 3) reproductive division of labor. Contrast presocial.

Eutheria: the placental mammal clade that arose ~161 MYA. Eutherians lack epipubic bones, allowing for an expanding abdomen during pregnancy.

eutrophication: the process by which a body of water becomes enriched with dissolved nutrients, such as nitrogen and phosphates, that stimulate the growth of microbial aquatic life, which typically results in depleting the oxygen dissolved in the water.

evaporation: conversion of water into vapor.

evening primrose (aka willowherb): an angiosperm of ~650 species in 17 genera in the Onagraceae family, including herbs, shrubs, and trees residing in every biome from boreal to tropical.

evo-devo: an informal term for evolutionary developmental biology.

evolution (evolutionary biology): the process of adaptation, most apparently seen as a distinctive change across successive generations of a population.

evolutionary biology: the subfield of biology concerned with the organic processes of evolution.

evolutionary psychology: the view that innate animal psychological traits are evolved adaptations.

evolvability: the capacity for adaptive evolution.

ex vivo (Latin for “out of the living”): something which takes place outside an organism. Contrast in vivo.

exaptation: a pre-adaptation. Elisabeth Vrba and Stephen Jay Gould coined exaptation to avoid the teleological implications of pre-adaptation. See pre-adaptation.

exocarp (aka epicarp): the outermost layer of a fruit pericarp.

exocrine gland: a gland that secretes its product into ducts that lead directly to an external environment. Exemplary exocrine glands include mammary, mucus, salivary, sweat, stomach, liver, prostate, and pancreas. Compare endocrine gland.

exocytosis: the cellular process of secreting proteins outside the cell. Contrast endocytosis.

exon: a polynucleotide sequence in a nucleic acid that codes for protein synthesis. An exon is copied and spliced together with other such sequences to form messenger RNA. Compare intron.

exoskeleton: an external skeleton. Arthropods have exoskeletons. Contrast endoskeleton.

exosphere: the outermost layer of the atmosphere, reaching halfway to the Moon (190,000 km).

extein: the portion of a protein receiving an intron. See intein.

extinction: the demise of a species. See background extinction, mass extinction.

extinction event: a duration of mass extinction.

extra dimensions (ED): spatial dimensions beyond the 3 (3D) that are observable. See 4D and HD.

extremophile: an organism that thrives in an environment adverse to most life. There are various extremophiles, each adapted to specific harsh conditions.

eye: an organ of vision.


facilitated variation (aka positive selection): an adaptive change evoked via ecology.

family (biological classification): a major group of shared morphological similarities. In the generally accepted system, family is above genus and below order. For example, maple trees (family) are hardwoods (order), angiosperms (class), vascular plants (phylum), plants (kingdom).

fat: a broad group of compounds comprising carbon, hydrogen, and oxygen; a subgroup of lipids. See saturated fat, unsaturated fat.

fatty acid: a carboxylic acid with a long aliphatic tail (chain).

fauna (plural: faunas or faunae): an animal (metazoa). See flora.

Faustian bargain: in the legend, Faust traded his soul to the devil in exchange for knowledge. To strike a Faustian bargain is a willingness to sacrifice anything to satisfy a limitless desire for knowledge or power.

feldspar: a silicate-based mineral that makes up as much as 60% of the Earth’s crust.

felsic: rocks, magma, and silicate materials enriched with aluminium, potassium, and/or sodium. Granite is the most common felsic mineral. Felsic is a portmanteau of “feldspar” and “silica.” Felsic rocks over 65% silica. Contrast mafic.

fermentation (biochemistry): a chemical process of breaking down molecules anaerobically. Glycolysis is a fermentation process.

fern (aka Pteridophyta): the first pteridophyte, emerging 360 MYA.

Fertile Crescent: the geographic area from the upper Nile River in Egypt through the Middle East to the Persian Gulf, including the regions of Mesopotamia and the Levant.

fetus: an unborn nascent vertebrate after passing through the earliest developmental stages, having attained its basic body structural plan. See embryo.

field: an energy associated with a spacetime point or region.

fig (aka common fig, Ficus carica): a dioecious tree or large shrub with a smooth white bark that produces an unusually structured fruit of the same name. There are ~850 species of trees, shrubs, vines, epiphytes, and hemiepiphytes in the Ficus genus.

finch: a small to medium-sized songbird in the Fringillidae family the primarily eats seeds. Many birds in other families are commonly called finches.

fingerling: a small fish, typically used to characterize a developmental stage to becoming a larger fish.

fire: the process of rapid oxidation of a material in an exothermic (energy-releasing) chemical process termed combustion.

fire coral: a colonial marine organism that looks like coral but is more closely related to jellyfish and other stinging anemones.

firefly: a winged beetle notable for its production of bioluminescence, commonly in the tail. 2,000 species are known, found in tropical and temperate zones, particularly marshlands and wet woods. A larva is a glowworm.

fish: a gill-bearing, aquatic animal lacking limbs with digits. 32,000 species are known. Most fish are endothermic.

fission (cytology): cell division into 2 (binary fission) or more (multiple fission) cells.

fission yeast (Schizosaccharomyces pombe): a unicellular eukaryote with rod-shaped cells which maintain their shape by growing exclusively through their cell tips; dividing via medial fission to produce 2 daughter cells of equal size.

fission-fusion sociality: a dynamic social group comprising a larger community with sub-groups, including families and close friendships. This awkward term refers to the dynamics of group fusion (merging), such as for sleeping together for safety, and fission (splitting up), such as foraging in small groups during the day. Various social animals have fission-fusion sociality, including fish (guppies), cetaceans (dolphins), ungulates (deer), elephants, most mammalian carnivores (lions, hyenas), and primates.

fitness (evolutionary biology): the relative ability to survive and reproduce.

flagellate: an organism or gamete with a whip-like organelle for propulsion.

flagellum (plural: flagella): a whip-like appendage protruding from a cell, employed for sensation and locomotion. Compare cilium.

flatworm (aka platyhelminth): a relatively simple unsegmented, bilateral (head and tail), soft-bodied worm. Flatworms have no specialized respiratory or circulatory organs. Their flatness lets oxygen and nutrients diffuse through them. Over half of the 15,000+ known flatworm species are parasitic. Compare roundworm.

flea: a wingless, blood-sucking parasitic insect.

flora (plural: florae or floras): plants. See fauna.

Flores: an island in the eastern half of Indonesia; one of the Lesser Sundra Islands.

florigen: a plant signaling molecule that initiates flowering; also known as the protein flowering locus t (ft).

fluid: a substance that deforms (flows) under an applied shear stress. Gases, plasmas, and liquids are fluids. Contrast solid.

fly: a small flying insect with a single pair of wings, adapted for aerial agility.

foliage: a mass of leaves as a plant feature.

folkway: a traditional behavior that is a norm.

food chain: a hierarchy of organism consumption, from autotroph through herbivore(s) to predator(s).

food web: the energy production and consumption interrelations between biota in an ecosystem.

forage: search for food.

forage fish (aka prey fish, bait fish): small pelagic fish which are prey for larger predators.

foraminifera: a large phylum of amoeboid protists; among the most common marine plankton species.

fossil fuel: a fuel formed from dead organisms. Coal, natural gas, and petroleum are fossil fuels.

fractal: a scale-invariant self-similar set of patterns.

fragmentation (biology): a form of asexual reproduction, where a new organism grows from a fragment of the parent. Some plants are capable of fragmentation.

Frailejón (aka Fraylejón): a daisy subshrub of 88 species in the Espeletia genus which lives in the páramo ecosystem.

free rider: an organism that gains a benefit without the usual effort or cost.

free-tailed bat: a bat in the Molossidae family; typically, robust and strong fliers with relatively long and narrow wings. The term free-tailed refers to their unusually long tail.

frog: a largely carnivorous group of tailless amphibians with short, stout bodies. With ~5,000 species, frogs are one of the most diverse vertebrate orders. Most frogs live in tropical rainforests. Warty frogs tend to be termed toads. This is an informal convention, not based on evolutionary descent or taxonomy.

frondose: bearing fronds.

fruit (botany): a plant ovary containing seeds that is a sweet-tasting gift to animals by a flowering plant in a gambit to disseminate its progeny.

fruit bat (aka Old World fruit bat, flying fox, megabat): a suborder (Megachiroptera) of Old World bats with an excellent sense of smell. Most have large eyes, adapted to low light. Some species use echolocation via clicking their wings to produce biosonar signals. So-called megabats, which can have a wingspan reaching 1.7 meters, also come in tiny varieties, with 6 cm wingspans.

fruit fly: a fly in the Tephritidae family that primarily that feeds on unripe or ripe fruit. Sometimes called a “true” fruit fly, as contrasted to vinegar flies that are called fruit flies. Compare vinegar fly.

fry: a recently hatched fish.

full-life hypothesis: a hypothesis by Ishi Nobu that all organisms may live natural “full” lives via rate-of-living related to lifespan.

fumarolic (vent): a hole in a volcanic region from which hot gases and vapors issue.

functional group (chemistry): the specific group of atoms within a molecule responsible for the molecule’s characteristic chemical reactions.

fungus (plural: fungi): a kingdom of eukaryotes that includes microorganisms such as yeast and molds, as well as macroscopic mushrooms.

fur: the hair of animals, especially mammals.


Gaia: a theory by English environmentalist James Lovelock that Earth acts as “a single physiological system.”

Evolution is a tightly coupled dance, with life and the material environment as partners. From the dance emerges the entity Gaia. ~ James Lovelock

galago (aka bushbaby): a small, slow-moving nocturnal prosimian native to continental Africa.

Galápagos Islands: an archipelago of 18 large and 3 small volcanic islands in the Pacific Ocean near the equator, 972 km west of Ecuador.

Galápagos marine iguana: a marine iguana found only on the Galápagos Islands, capable of diving 9 meters to graze on algae and seaweed.

gall: an outgrowth on the surface of organisms. Commonly used for abnormal plant growths invoked by various parasites, including bacteria, fungi, and insects.

game theory: the study of strategic interaction between rational decision-makers; specifically, theorization of outcomes and dynamics in situations involving parties with conflicting interests. Modern game theory was developed in the early 1940s and further evolved in the 1950s. Compare decision theory.

gamete: a cell or cell nucleus that undergoes sexual fusion to form a zygote. In animals, gametes are eggs and sperm cells. Plant germ cells produce ovules and pollen.

gametophyte: the gamete-producing generation in the life cycle of a plant; the prothallus in ferns, and the embryo sac in angiosperms.

gamma ray: electromagnetic radiation above 10 exahertz (>1019 Hz); very high energy/frequency radiation.

gannet: a large seabird in the Morus genus that hunts by diving into the sea from height. Gannets can dive from 30 meters up, achieving speeds of 100 km/h as they strike the water. This lets them catch fish much deeper than other diving birds.

gas: a fluid that may be airborne.

gastropod: a slug or snail.

Gaul: the region of France during Roman times. Gaul was ruled by the Romans 103 bce–486 ce.

Gaza: one of the oldest cities in the world; first settled 5 TYA, during the Bronze Age. Now a dilapidated Palestinian city, Gaza is on Mediterranean coast.

gazelle: an antelope of 13 species.

gender: designation of female or male of a species. See sex.

gene: the idea that nucleic acids provide instructions for producing an organic molecule, typically a protein. Genes do not exist; they are merely a construal. The actuality of genetics is more intricate than supposed by matterist geneticists, as heritable bioproduct information is stored energetically, with organic molecules as illusory material substrates. See egene.

organic molecules as illusory material substrates.

gene conversion: a recombination transfer between DNA sequences.

gene expression: employment of a gene; the conceptual process by which genetic information is used to synthesize a bioproduct.

gene product: the biochemical material resulting from gene expression. A protein is the typical gene product, though RNA is also a gene product.

gene regulation: control of gene expression, including stifling gene expression.

generalist (ecology): a species with considerable tolerances to environmental changes. Contrast specialist.

genetic code: the conceptual rulebook by which information is encoded in genetic material (DNA or RNA sequences).

genetic drift (aka allelic drift): a difference in genome between species in a hereditary lineage.

genetic mutation: a change in a DNA sequence.

genetic recombination: the process of transferring broken-off molecules of nucleic acid to a different DNA sequence.

genetics: the study of heredity and variation in life forms at the molecular level. The 4 major subdisciplines of genetics are transmission genetics (heredity), molecular genetics (chemistry), population genetics (traits in populations), and epigenetics (influences of living on inheritance).

genitalia (aka genitals): a sex organ.

genome: the (idea of the) entire set of genes within an organism. Like genes, a genome is merely a concept, not phenomenal.

genophore: a package of DNA in a prokaryote’s nucleoid. Compare chromosome.

genotype: the energetic constitution of an organism, as artifactually represented by genome. The gen in genotype refers to genesis (not genetics).

genus (plural: genera): a category of organisms, more generic than species.

geoglyph: a large (>4 meters) design or motif formed on the ground using durable landscape elements, typically clastic rocks.

geographic harmonic (aka geoharmonic): the energetic resonance of a biome (affecting biota).

geology: the study of the solid matter that comprises Earth, especially in the crust.

geophyte: a plant that employs an underground energy storage organ.

germ: see pathogen.

germ layer: a primary layer of cells during embryogenesis.

germ plasm theory: a theory espoused by August Weismann that the only carriers of inheritance are germ cells (eggs and sperm).

German cockroach (Blattella germanica): a small cockroach, tan to almost black colored. The German cockroach can barely fly. Omnivorous scavengers, German cockroaches are ubiquitous throughout much of the human world, where they are considered an especially persistent domestic pest. Though known as the “German” cockroach in English-speaking countries, the Germans call it the “Russian roach.”

germline cell: the line (sequence) of cells that may be passed to offspring. Contrast soma.

gill: a respiratory organ common to aquatic animals. All fish have gills to dissolve the oxygen in water and excrete CO2. Some aquatic creatures, such as hermit crabs, have gills that allow atmospheric respiration as long as they stay moist.

ginkgo: a long-lived large tree with slow reproduction rate, sometimes reaching 50 meters. Ginkgo have unique fan-shaped leaves.

giraffe: an African even-toed ungulate ruminant with an exceedingly long neck, making it the tallest living terrestrial animal.

glacial period (aka glaciation): a period of glaciers, typically thousands of years, within an ice age, marked by colder temperatures and glacial advances. By contrast, interglacials are periods of warmer climate within an ice age. The last glacial period ended 15,000 years ago. The Holocene epoch was an interglacial. Thanks to intense human pollution, Earth is heading into hothouse.

glaciation: the process of glacier formation.

glia: the predominant cell type in animal brains. Neurons (nerve cells) support glial cells via their interfaces outside the brain.

gliding bacterium: a bacterium that moves under its own power, without a flagellum. Gliding is typical in cyanobacteria, myxobacteria, and cytophaga-flavobacteria.

glomerulus (plural: glomeruli): a small, intertwined mass (as of capillaries, nerve fibers, or organisms).

glowworm: the larva of a firefly.

glucocorticoid: a corticosteroid that regulates glucose metabolism. The most important human glucocorticoid is cortisol.

glucose (C6H12O6): a simple sugar used in glycolysis to form ATP.

glycerol: a simple alcohol compound comprising 3 hydroxyl groups (3 molecules of hydrogen and oxygen).

glycolysis: a metabolic pathway of 10 reactions that results in free energy; often used to form ATP.

glycoprotein: a protein containing a carbohydrate (oligosaccharide chain) attached to a polypeptide side chain.

glycoside: an organic molecule in which a sugar is bound to another functional group.

Gnetum: a genus of gymnospermous tropical trees, shrubs, and lianas which may have been the first plants to be insect pollinated.

goat: an even-toed bovid, closely related to sheep.

goby: a fish in one of the most specious families of fish (Gobiidae), with more than 2,000 species in over 200 genera.

Godetia: flowering plants, mostly annuals, in the genus Clarkia; native to western North America, except for single species that resides in Chile, commonly called Sangre de toro, Inutil, and Huasita (Clarkia tenella).

golden hamster (aka Syrian hamster, Mesocricetus auratus): a hamster endemic to arid areas of northern Syria and southern Turkey.

gomphothere: a family of elephant-like animals that lived 12–0.7 MYA, before being hunted to extinction by humans.

gonad: a reproductive gland that produces the gametes (sex cells) and sex hormones of an organism. The male gonad (testicle) produces sperm. The female gonad (ovary) produces eggs. Both gametes are haploid germ cells.

Gondwana (510–200 MYA): a supercontinent prior to Pangea (300 MYA); later becoming the southernmost of 2 supercontinents (Laurasia to the north) 200 MYA. Gondwana was the progenitor of the landmasses in today’s southern hemisphere: Antarctica; Australia; the Arabian Peninsula and Indian subcontinent, both now part of the northern hemisphere; Madagascar, Africa; and South America.

gorilla: a large, ground-dwelling ape that lives in the African forest.

gossamer-winged butterfly: a small (typically <5 cm), brightly colored butterfly in the Lycaenidae family, with over 6,000 species worldwide.

gracile: a slender bodily build.

grade (biology): similarity between 2 organisms.

grammar: the overarching rules for proper use of language, including semantics, syntax, punctuation, and spelling.

Grande Coupure (33.9 MYA): the mass extinction event that delineates the Eocene and Oligocene epochs in the Paleogene period. Marine and aquatic fauna were hardest hit, with a major turnover in European animal species 33.5 MYA. The Grande Coupure occurred during global cooling, not obviously linked with any catastrophic geological event, though likely during extended volcanic activity.

grandmother hypothesis: the surmise by George Williams in 1957 that menopause evolved so that grandmothers could help rear offspring of a succeeding generation.

granite: a course-grained igneous rock, at least 20% quartz by volume.

grass: an angiosperm in the prodigious, ubiquitous Poaceae family of versatile monocots that grow on all continents. Grasses have small flowers and sheathing leaves covering hollow stems. They include cereals and bamboo, but not other plants commonly called grasses, such as seagrasses, rushes, and sedges (though rushes and sedges are related to grass).

grasshopper: a predominantly tropical, ground-dwelling, herbivorous insect with powerful hind legs for leaping; extant for 250 MYA, now with 11,000 known species.

gravity: an entropic spacetime distortion caused by mass. Generally considered one of the 4 fundamental forces, though that is something of a misconception, as the other 3 interactions – strong, weak, and electromagnetism – are significant to subatomic particles, whereas gravity is not.

Great American Interchange: the period of intercontinental species migration between North and South America 3 MYA. See Nearctic and Neotropic.

Great Dying (252 MYA): Earth’s most severe mass extinction event, at the Permian–Triassic (P–T) boundary.

Great Oxidation Event (aka Great Oxygenation Event, GOE) (beginning 2.45 BYA): biologically induced augmentation of dioxygen (O2) into Earth’s atmosphere. Cyanobacteria begat the ‘event’ via photosynthesis on a massive scale. The first oxygen-generating organisms arose long before, 3.4 BYA. The onset of Earth’s oxidation was neither an “event” nor “great.” The initial oxidation was only a few parts per million of O2. Atmospheric oxygen did not begin a serious upswing until 850 MYA.

Great Rift Valley: a geographic trench in East Africa, best known for fossils found there of early hominids. The Great Rift Valley runs from the Afar Triple Junction: 3 plates – the Nubian, Somalian, and Arabian – that intersect where the Gulf of Aden and the Red Sea meet, to central Mozambique.

greater hooked squid (Onykia ingens): a deep-water subAntarctic squid. Females are twice as long as males.

Greek Dark Ages (aka Homeric Age) (12th to 9th century bce): the period of Greek history from the end of the Mycenaean palatial civilization to beginning of the Greek poleis (city-states). Compare Dark Ages.

green anole (aka Carolina anole, American anole, red-throated anole, Anolis carolinensis): a small- to medium-sized arboreal lizard with a slender body. Males are 15% larger than females. Though related to iguanas, the green anole can change colors in a chameleon-like manner.

green iguana (aka American iguana, Iguana iguana): a large, arboreal iguana native to the Caribbean, and Central and South America.

greenhouse (climate): see hothouse.

greenhouse gas: a gas in the atmosphere that absorbs and emits radiation within the infrared range. The primary greenhouse gases in Earth’s atmosphere are carbon dioxide, methane, nitrous oxide, and ozone. Water vapor acts as a greenhouse gas.

Greenland shark (aka gurry shark, gray shark, Somniosus microcephalus): a large shark endemic to the frigid waters of the North Atlantic and Arctic oceans. Greenland sharks are also adapted to being comfortable at great depths.

gregarious: highly social.

group selection: the unsubstantiated hypothesis that evolution acts at the level of the group, not individuals; developed by Charles Darwin. See kin selection.

If one man in a tribe invented a new snare or weapon, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather better chance of the birth of other superior and inventive members. ~ Charles Darwin

guanine (G) (C5H5N5O): a nucleobase of DNA and RNA. Guanine is complementary to cytosine. Guanine has a variety of biological employment, notably for reflective optical effects in the skin of fish for camouflage, and in the eyes of deep-sea fish, and some reptiles, such as crocodiles.

Guinea baboon (aka western baboon, red baboon, Papio papio): the smallest species of baboon, endemic to a small range in westernmost Africa, inhabiting dry forests, gallery forests, steppes, and savannas. The Guinea baboon is diurnal and terrestrial, though it sleeps in trees at night for safety. The number of suitable trees for sleeping limits its group size and range. Troops are up to 200 members. Guinea baboons are highly communicative. Socially a troop comprises a complex multilevel society. Unlike other baboons, adult male Guineas are tolerant and cooperative, forming social bonds with other males regardless of kin relation.

guru: a realized teacher.

gymnosperm: a seed-producing plant that arose in the early Carboniferous, 340 MYA. Gymnosperm include conifers (e.g., pine, fir), cycads, ginkgo, and gnetophytes.

gyne: the primary reproductive caste in social insects (ants, bees, wasps, termites). Whereas the typical female worker is sterile, gynes are destined to become queens. A colony with a single queen is monogyne (e.g., honeybees), whereas a colony with multiple queens (e.g., ants) is polygyne.

gynogenesis: asexual reproduction related to parthenogenesis, but with the requirement that an egg be stimulated by presence of sperm – without incorporating the sperm’s genetic material – in order to develop.

gynosome: the penis of a female booklice.

gyre: a conceptual framework treating a physical system as a dynamic vortex. A gyre is characterized by its structure, qualities, thermodynamics, and interactions.

gyroid: an infinitely connected triply periodic minimal surface, discovered by Alan Schoen in 1970. A gyroid separates space into 2 oppositely congruent labyrinths of passages.


habitable zone (aka circumstellar habitable zone, Goldilocks zone, comfort zone): a range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The radiant energy a planet receives from the star it orbits is a critical factor.

habitat: the relevant aspects of an environment in which a species population lives.

Hadean (4.55–3.9 BYA): the 1st geologic eon, originally thought to be before life originated on Earth (but life started 4.1 BYA).

hadron: a composite subatomic particle made of a variety of quarks.

Hagenberg (mass extinction event 358 MYA): the last of 8 to 10 extinction pulses during the Devonian. The Hagenberg extinction event, on the boundary with the Carboniferous, affected both marine and terrestrial biomes.

hairstreak: a small butterfly with striped markings under its wings, in the Lycaenidae family.

Hallucigenia: a genus of small Cambrian tubular animals, 0.5–3.5 cm long.

halophile: an organism that lives in a salty habitat.

Halszkaraptor: a unique genus of feathered, largely aquatic, maniraptoran therapod with duck-like legs for walking and forelimbs well-adapted for swimming. Only 1 species – H. escuilliei – is known.

hamster: a burrowing, crepuscular group of rodents of 6–7 genera and ~25 species. Hamsters eat primarily seeds, fruits, and vegetation, occasionally munching burrowing insects. Hamsters are larder hoarders, using their expandable cheek pouches to transport food to their burrows.

haplodiploidy: a sex-determination system where the sex of offspring is determined by the number of sets of chromosomes received. Female eusocial (Hymenopteran) insects, such as bees, wasps, and ants, are diploid, but males are haploid because they develop from unfertilized, haploid egg cells.

haploid: an organism having one set of chromosomes.

harvester ant: an ant that collects seeds and stores them in a communal granary.

haustorium (plural haustoria): an appendage from the root of a parasitic plant or the hyphal tip of a parasitic fungus, used to penetrate a host’s tissue and draw nutrients from it.

HD (holistic dimensionality): the totality of cosmic dimensions. HD refers to the universe having more than 4 dimensions (4D = 3 spatial dimensions and 1 time vector). HD = 4D + ED, where ED = extra (spatial) dimensions.

hearing: sound detection. Compare audition.

helot: a Spartan slave. The Spartans were savage to their helots.

hematophagy: the practice of feeding on blood.

hemiepiphyte: a plant that spends part of its life as an epiphyte.

hemimetabolous: a type of metamorphosis in which physical development proceeds from egg to nymph to adult. Compare ametabolous, holometabolous.

hemocoelic: having a blood vascular system.

hemoglobin (aka haemoglobin; abbreviated Hb or Hgb): the iron-containing oxygen-transport protein in red blood cells of almost all vertebrates (excepting crocodile icefish). See icefish.

hemolymph (aka haemolymph): the fluid in the circulatory system of arthropods that is functionally analogous to blood and tissue fluid in vertebrates.

herbaceous (plant) (shortened form: herb): an angiosperm that has leaves and stems which die down to the ground at the end of the growing season. Herbaceous plants have no persistent woody stem above ground. Herbaceous plants may be annuals, biennials, or perennials. Contrast arborescent.

herbivore: a heterotrophic organism that eats plant-based foods. Compare omnivore, predator, and saprovore.

heredity (genetics): inheritance of traits from one generation of life form to the next.

hermaphrodite: an organism that has male and female sex organs (simultaneous hermaphrodite). A sequential hermaphrodite changes sex some time during its life.

heron: a long-legged freshwater and coastal bird of 64 species, some of which are called egrets or bitterns.

herpetology: the study of amphibians and reptiles.

Herrerasauridae: the order of the earliest dinosaurs, appearing in the fossil record 233 MYA, in the Late Triassic. Herrerasaurids were extinct by the end of the Triassic, leaving no descendants.

heterochrony: an evolutionary change in development, whether in timing or rate of events, leading to altered morphology. Contrast heterotopy.

heterogamy (reproductive biology): sexual reproduction, as contrasted to parthenogenetic generation; in the context of alternation of generations. Contrast parthenogenesis.

heterokaryon: a special form of syncytium, in which a life form, such as a plasmodium, has multiple nuclei of different genetic origin.

heterosporous: a plant with 2 spore sizes. Contrast homosporous.

heterotopy: an evolutionary change in embryonic development spatially, which may be complementary to heterochrony.

heterotroph: an organism that cannot make its own food. All animals are heterotrophs. Compare autotroph.

heuristic (psychology): a simple, efficient rule used to form judgments, solve problems, or make decisions. Compare algorithm.

hexapod: a 6-legged invertebrate.

Himalayas: a young mountain range formed by the Indian subcontinent moving north and slamming into Eurasia. 9 of the 10 highest peaks on Earth are in the Himalayas.

hinny: a hybrid between a stallion and a female donkey. Compare mule.

hippopotamus: a large, mostly herbivorous mammal of sub-Saharan Africa. Hippos are semiaquatic, inhabiting lakes, shallow rivers, and mangrove swamps. Despite resembling oversized pigs, their closest are cetaceans, from which they diverged 55 MYA.

histology (aka microanatomy): the study of cell and tissue anatomy via microscopy.

Hittites: an ancient Anatolian people who established an empire in north-central Anatolia 1600–1180 bce.

HIV (human immunodeficiency virus): an enveloped RNA retrovirus, termed for the immune system deterioration it causes, leading to AIDS (acquired immunity deficiency syndrome).

holdfast: a root-like structure that anchors aquatic sessile organism, such as seaweed and sponges, to a substrate.

Holocene (11,700 years ago–1940): the interglacial epoch during icehouse before Earth headed into hothouse from manmade pollution. The current hothouse epoch – the Omegacene – has yet to be recognized. The Pleistocene preceded the Holocene.

holometabolous: a type of metamorphosis with 4 stages: egg, larva, pupa, adult. Compare ametabolous, hemimetabolous.

homeobox: a genetic sequence involved in regulating anatomical development.

homeodomain: a set of amino acids which confer a regulatory mandate to the proteins which contain them.

homeosis: the developmental transformation of one organ into another.

homeostasis (biology): a regulatory process by which an organism strives for holistic health. The term, from Greek, literally means “steady-state”: a rather ridiculous label to try to pin on a living organism, which cannot possibly maintain a constant status. Less mechanistic revision of the term from its original conception emphasizes the regulation inherent in maintaining health at whatever level the term is applied to: whether cellular, a specific internal system, or the whole organism. Compare autopoiesis.

homeostasis (physics): a tendency toward stability within a system.

homeotic gene (evolutionary development biology): a gene which regulates the development of anatomical structures via transcription factor programming, which affects genes in genetic regulatory pathways.

hominid: an ape descendant, some of which became hominin. Compare anthropoid.

hominin: the hypothesized clade that descended into humans. Compare anthropoid.

hominoid: a primate of either hominid or anthropoid under the now obsolete Linnaeus system. Used herein for a primate with features that indicate evolution away from apes.

Homo (2.4 MYA–now): a diverse genus of hominids which includes modern humans.

homogeneous: the same at all locations. Compare isotropic.

homologous recombination: exchanging nucleotide sequences between similar genes. Contrast non-homologous recombination.

homologue (evolutionary biology): incremental evolution. Contrast analogue.

homoplasy: the seemingly same trait in organisms of different species, but the trait did not evolve from a common ancestor; instead, developed via convergent evolution.

homosporous: a plant with a single spore size. Contrast heterosporous.

honey possum: a tiny marsupial (7–11 grams), half the weight of a mouse; native to southwestern Australia. The honey possum is a nectivore.

horizontal gene transfer (HGT): sharing genetic material between organisms. In contrast, vertical gene exchange is genic transfer from parent to offspring.

hormone: an organic chemical intended for long distance intercellular communication; from the Greek word for impetus.

hornwort: a group of bryophytes that evolved during the Devonian, now of 100–150 species, found worldwide in moist soils.

horse (Equus ferus caballus): an odd-toed ungulate. Men began to domesticate horses ~4,000 bce. See equid.

Horus: one of the oldest and most important deities in ancient Egyptian religion; the god of the Sun, war, and safety.

host (biology): a cell, virus, or organism in/on/to which another organism has an interest or relationship.

host cell: a cell hosting an endosymbiont. Eukaryotes arose from an archaean hosting bacterial endosymbionts.

host dependency factor: a cellular component that a virus needs to survive, replicate, or spread.

host range: the cell type(s) that a virus infects by recognizing cell surface receptors.

hothouse (aka greenhouse): a duration lasting millions of years where Earth is hot and typically humid, completely lacking continental glaciers. Contrast icehouse.

house dust mite: a homebody mite, found even in the cleanest house. House dust mites select food already partly decomposed by fungi, as they literally have no stomach for digestion.

house finch (Haemorhous mexicanus): a small residential (non-migrating) songbird now found throughout the US and much of Mexico, and in southern Canada.

hoverfly (aka flower fly, syrphid fly): a fly of ~6,000 species in 200 genera, in the Syrphidae family; often seen hovering over nectaring flowers.

human (Homo sapiens): a bipedal, largely furless primate.

Humboldt Current (aka Peru Current): a cold, low-salinity ocean current that flows north along the west coast of South America from the southern tip of Chile to northern Peru.

hummingbird: a bird in the family Trochilidae. Hummingbirds are among the smallest of birds, including the smallest: the 5 cm bee hummingbird.

hybrid: an organism that is a combination of 2 species.

hydra: a genus of freshwater invertebrates of ~25 species, with a body consisting of a thin, typically translucent tube up to 30 mm long.

hydrocarbon: a molecule comprising only hydrogen and carbon.

hydrogen (H): the element with atomic number 1, constituting in its simplest form a single proton and solitary electron (protium, 1H). Hydrogen is the lightest element, and the most abundant chemical in the universe, comprising 75% of cosmic baryonic mass. Hydrogen plays an especial role in acid-base chemistry and is a proton donor in many reactions between soluble molecules.

hydrogen sulfide (H2S): a colorless gas with the foul odor of rotten eggs. H2S is poisonous, corrosive, and flammable.

hydrological cycle (aka water cycle): the cycling of water in the biosphere.

hydrophilic: having a high affinity for water.

hydrophobic: having a low affinity for water.

hydrosphere: the bioelement of water, including the participants in the water cycle.

hyena: a dog-like carnivorous mammal that arose in Eurasia during the Miocene 22 MYA and developed into 2 distinct groups: robust bone-crunchers and lightly-built dog-like creatures more given to scavenging. Extant hyenas live in Africa and Asia.

Hyksos: a tribe from west Asia who took over the eastern Nile Delta around 1800 bce.

hylomorphism: the belief that all things are a combination of matter and form. The form of life is in the soul. Aristotle conceived hylomorphism.

hyoid apparatus: the bones or cartilage which suspend the tongue, and in mammals the larynx.

hyperthermophile: an organism that can survive at 80 °C or greater.

hypothesis: a guess gussied up in scientific garb. Under the scientific method, hypotheses are ripe for falsifiability testing. Compare theory.

Hypsilophodont: a genus of relatively small (1–2 meter), agile, bipedal, herbivorous ornithopods.


Iberian emerald lizard (Lacerta schrieiberi): a lizard endemic to the Iberian Peninsula (Portugal and western Spain).

ice: frozen water.

icefish (aka notothenioid): a suborder (in the Perciformes order) of Antarctic and subAntarctic fish which live mainly in the Southern Ocean. While most animals have 45% hemoglobin in their blood, crocodile icefish (aka white-blooded fish) have only 1%. They flourish because of the high oxygen content of the cold Southern Ocean waters, and partly because oxygen is absorbed and distributed directly by their blood plasma. Oxygen solubility greatly increases when cold. The cost is that crocodile icefish expend twice as much energy in cardiac output as other icefish with higher hemoglobin concentration.

icehouse (aka ice age): a span of millions of years where the world has continental ice sheets, tending toward cool and arid climate. Contrast hothouse.

ichthyology: the study of fish.

Ichthyosauria: an order of large marine reptiles that appeared 250 MYA.

ideogram: a written symbol representing of a concept. Compare pictogram.

igneous: rock formed by cooling and solidification of magma or lava. Compare sedimentary and metamorphic. See basement.

iguana: a genus of herbivorous tropical lizards.

illusion: mistaken perception; something deceptive by a false impression.

immanence (religion): the belief that there is an active divine presence in the material world. Contrast transcendence. Compare supremism.

immune system: a biological system that protects against disease, especially infection. For macrobes, an immune system acts as a microbiome management system.

in vivo (Latin for “within the living”): something within an organism. Contrast ex vivo.

inclusive fitness: the hypothesis of an evolutionary strategy whereby conspecifics altruistically help one another. See kin selection.

indehiscent: not dehiscent.

indigenous: naturally occurring in an environment or biome. Compare native, endemic.

Indonesia: a nation comprising over 13,000 islands in Oceania.

Indus Valley civilization (aka Harappan civilization) (~7,000–1900 bce): a peaceful, prosperous ancient civilization in the Indus Valley (now western India & Pakistan).

industry (archeology): a collection of contemporaneous artifacts indicting a level of technological accomplishment.

influenza (aka the flu): an infectious disease of birds and mammals caused by RNA viruses.

infrared (IR): electromagnetic radiation between 1 and 400 THz (terahertz). Most thermal radiation at room temperature is infrared. Infrared is emitted or absorbed by molecules when they change their rotational or vibrational mode.

infructescence: the fruiting stage of an inflorescence (flower).

inquiline: an animal that lives commensally in the dwelling of another species. The most diverse types of inquiline are found in the nests of social insects, especially ants and termites, where a single colony may support dozens of different inquilines. Inquiline is a somewhat slippery term. Parasites are by definition deleterious to their hosts. In contrast, inquilines gain from their host association, by taking advantage of host services and facilities, but do not necessarily bring their hosts down.

insect: an arthropod with a tripartite body (head, thorax, and abdomen), a chitinous exoskeleton, 3 pairs of jointed legs, a pair of compound eyes, and a pair of antennae. Insects are among the most diverse groups of animals, with over a million known species.

insectivore: an insect eater.

insertion (genetics): a mutation via inserting 1 or more nucleotides. Contrast deletion.

instinct: an innate ability or impulse.

intein: a self-splicing protein segment which can excise itself from a larger protein molecule and rejoin a polypeptide chain (extein) via a peptide bond.

intelligence: an attribution for consistently behaving appropriately. Also used for the process of gathering and analyzing information.

intent: volition; willfulness.

interconnection: mutual connection.

interdependence: a system where one feature dynamic may affect another.

interferon: a protein made and let loose by a host cell in response to detecting a pathogen.

interglacial: a period of warmer climate within an ice age (icehouse). Compare glacial period.

internode (botany): growth between an established plant and its nascent offspring during vegetative reproduction.

interphase: the period of the cell cycle during which a cell lives its everyday existence. Interphase is 90% of a cell’s life cycle. See anaphase, telophase.

interspecific: occurring between or among different species. Contrast conspecific.

introgression (genetics): introduction of genes from one species into another.

intron: a polynucleotide sequence in a nucleic acid that does not code for protein synthesis. Introns are removed before translation of messenger RNA. Compare exon.

inversion (genetics): a mutation by rearranging a gene sequence. Compare translocation.

invertebrate: an animal that is not a vertebrate.

iridescence (aka goniochromism): a change of color appearance in a material based upon angle of view or illumination. Iridescence is often created via structural coloration (microstructures which create light interference patterns).

Irish elk (aka Irish giant deer, Megaloceros giganteus): one of the largest deer that ever lived, which went extinct ~7,700 years ago. Its range extended across Eurasia during the Pleistocene, from Ireland to Siberia and China.

iron (Fe): the element with atomic number 26; a metal. Iron is the most common element (by mass) in Earth, forming much of its core.

Iron Age (~1300–500 bce): the last (3rd) principal period of the 3-age system, noted for widespread use of iron and the development of steel. See Stone Age, Bronze Age.

isometric: relating to or characterized by equality of measure.

isoprene (2-methyl-1,3-butadiene (C5H8)): a colorless, volatile, organic liquid produced by many plants; polymers of isoprene are the main component of natural rubber.

isotropic: the same in all directions. Compare homogeneous.


jellyfish (aka sea jelly): a free-swimming marine animal with a gelatinous bell shaped like an umbrella, trailing tentacles. Jellyfish are the oldest multiple-organ animal, having been around for at least 700 million years. ~2,000 jellyfish species are extant.

Judaism: the monotheist religion of the Jews.

jumping spider: an agile spider, with the best vision of all invertebrates, Jumping spiders have 4 pairs of eyes, including large anterior central eyes. Jumping spiders normally move slowly and quietly, but are capable of incredibly athletic jumps, either to snag prey or to avoid a threat. There are 5,000 distinct jumping spiders (the Portia genus), making up 13% of all spider species – the most specious spider. Jumping spiders are found everywhere but the polar regions.

junk DNA: a DNA sequence that does not code for producing a protein.

Jupiter: the 5th planet from the Sun; a gas giant 2.5 times the mass of all other planets in the system. Jupiter has 63 sizable moons, 1 more than Saturn.

Jurassic (201–145 MYA): the middle period of the Mesozoic era, following the Triassic period and preceding the Cretaceous. The Jurassic is best known for the predominance of dinosaurs as the largest life. By the beginning of the Jurassic, the supercontinent Pangea had begun rifting into 2 landmasses: Laurasia to the north and Gondwana to the south.

juxtacrine signaling: intercellular communication by direct contact. Compare paracrine signaling, endocrine signaling.


K–Pg boundary (mass extinction event) (66 MYA): the Cretaceous–Paleogene mass extinction event boundary that defines the end of the Mesozoic era. K is used for Cretaceous because C was already taken for Carboniferous.

katydid (aka bush cricket): a cricket-like insect in the Tettigoniidea family, with 6,400 species.

Kauai cave wolf spider (Adelocosa anops): an eyeless spider that lives in caves on Kauai island, Hawaii.

kelp: a large seaweed (brown algae), of which there are ~30 genera. Kelp often form dense forests which support a variety of marine animals.

Kelvin (K): an absolute temperature scale. Kelvin is the primary measurement unit in the physical sciences.

Kenyanthropus (3.5–3.2 MYA): a genus of hominid that walked upright, with a cranial capacity of early hominins.

keratin: a family of fibrous structural proteins, found in animal nails, claws, hooves, and other sturdy parts, including scales, skin, feathers, and hair. The only other biochemical substance with such toughness is chitin. See lignin.

kin selection: the theory that organisms altruistically help their relatives; mathematically developed by Ronald Fisher in 1930 and popularized by W.D. Hamilton in 1964.

kinase: an enzyme that promotes reversible phosphorylation. More generally, kinases act on and modify the activities of specific proteins.

kinetic energy: energy associated with motion.

kingdom (biological classification): the taxon above phylum and below domain. There are 4 eukaryotic kingdoms: protists, plants, fungi, and animals.

knowledge: cognition of facts or principles about Nature. Compare omniscience.

Komodo dragon (aka Komodo monitor): a gigantic lizard on the Indonesian islands of Komodo.


lacerta (aka true lizard, wall lizard): a lizard in the Lacertidae family, comprising over 300 species in 29 genera, native to Africa, Europe, and Asia.

Lake Duck (aka Argentine Blue-bill, Oxyura vittata): a small, South American stiff-tailed duck.

Lake Tanganyika: a large lake in Africa; the world’s longest freshwater lake, the 2nd-oldest, 2nd-largest by volume, and 2nd-deepest (in all instances after Lake Baikal in Siberia). Tanganyika refers to “great plain-like lake.”

Lake Rudolf: a lake in Kenya, now called Lake Turkana.

Lamarckism (aka Lamarckian inheritance, heritability of acquired characteristics, soft inheritance): the theory that an organism can pass on characteristics acquired during its lifetime to its offspring. Named after Jean-Baptiste Lamarck, who proposed the hypothesis. Long disparaged by Darwinists, the discovery of epigenetics has validated Lamarckism.

lamprid: a ray-finned fish in the Lampriformes order that are pelagic feeders, typically brightly colored, often with brilliant crimson fins. Lamprid body forms vary but are generally compressed laterally.

lancelet (aka amphioxus): a fish-like marine chordate of ~32 extant species.

language: a system of symbols with interrelated meanings.

large blue butterfly (Maculinea arion): a gossamer-winged butterfly native to northern Eurasia that deceives red ants (Myrmica sabuleti).

larynx (aka voice box (for humans)): a hollow tube connected to the top of the trachea in tetrapods; used for breathing, sound production, and protecting the trachea from food aspiration.

Last Glacial Maximum (26.5–19.5 TYA): the last period of peak glaciation on Earth.

lateral line: a sense organ system in aquatic vertebrate, chiefly fish, used to detect movement via vibration.

lateralization (avian vocalization): separate sounds from each bronchus.

Laurasia: the northernmost of 2 supercontinents that split from the supercontinent Pangea 200 MYA. Laurasia included most of the current continental landmass of the northern hemisphere. Gondwana was the southern portion of erstwhile Pangea.

laurel forest (aka laurisilva): a subtropical forest type with high humidity and relatively stable, mild temperatures. Laurel forests are dominated by broadleaf trees with glossy, evergreen, elongated leaves, known as lauroid or laurophyll.

Laurentia: a large continental craton created 1.5–1.0 BYA; now the North American Craton, after much movement and rotation. The craton now comprises eastern and central Canada, and most of the middle states of the United States. Precambrian basement rock at the southwest portion of the craton was deformed by continental collisions, begetting the Rocky Mountains.

larva (biology) (plural: larvae, larvas): the immature, wingless, and often wormlike (vermiform) feeding stage of a holometabolous insect hatched from an egg. The next development stage is as a pupa. Compare nymph.

law (natural philosophy): a conclusion about a universal tendency in Nature.

law of independent assortment: a hypothesis by Gregor Mendel that the expression of any 1 genetic trait is not influenced by another. This so-called law is bogus.

law of segregation: a hypothesis by Gregor Mendel that an allele in a diploid organism may express as dominant, masking a recessive allele that would express a different trait.

leaf: a vascular plant organelle, typically employed in photosynthesis. Leaves evolved to suit plants specific needs, optimized to constraints imposed by physics at the quantum level. See foliage.

learning: the process of constructing a conceptual framework.

lechwe: an African antelope, with adults 90–100 cm high at the shoulder, 70–120 kg. Herds, which may number many thousands, are usually a single sex. During breeding season, herds mix. While almost all females breed, only dominant males do. Males battle for mating privilege.

leghemoglobin: a protein that carries nitrogen or oxygen in plants.

legume: an herbaceous perennial plant or its fruit or seed. Well-known edible legumes include alfalfa, beans, carob, lentils, peanuts, peas, and soybeans.

lemur: a clade of prosimian, named after the lemures (ghostly spirits) of Roman mythology, owing to lemurs’ ghostly vocals, reflective eyes, and often nocturnal lifestyle. Lemurs are endemic to Madagascar, having arrived by rafting 62–65 MYA. Some lemurs were as large as male gorillas until after humans arrived on the island 2,000 years ago. The invasive humans wiped the large lemurs out.

lengyre (aka vital energy, chi (Chinese), prana (Hindu)): an organism’s HD life-force energy system.

leopard ground squirrel (aka 13-lined ground squirrel, striped gopher, squinney, Ictidomys tridecemlineatus): a ground squirrel widely distributed over the prairies and grasslands of North America, with 13 alternating brown and whitish longitudinal lines (sometimes broken into spots) on its back and sides.

lepidopteran: an insect in the diverse Lepidoptera order which includes moths and butterflies.

Levant: the geographical region encompassing modern-day Jordan, Israel, Lebanon, and Syria. The term Levant appeared in English in 1497, originally meaning “the East.” The Levant has been characterized as the “crossroads of western Asia, the eastern Mediterranean and northeast Africa.”

Lévy walk (aka Lévy flight): a random walk defined by step lengths. The term was coined by Benoît Mandelbrot, referring to Paul Lévy.

liana: a woody vine, rooted in the soil, that climbs trees to the canopy.

lichen: a composite organism comprising a fungus (mycobiont) and a photosynthetic (photobiont) cyanobacterium or algae.

life: anything capable of perceiving its environment.

life-history variable: a trait or aspect of an organism’s existence related to others; often viewed comparatively, as a trade-off with other, mutually exclusive possibilities.

light: electromagnetic radiation visible to the human eye, at a wavelength of 380–740 nanometers.

light-year: how far light travels in a year at light-speed (as fast as light can travel); the standard unit used to express astronomical distances. A light-year is ~9.461 trillion kilometers.

lignin: an amorphous polymer related to cellulose. Lignin is an integral part of the cell walls of plants and some algae. See chitin, keratin.

lignotuber: a woody swelling of the root crown in some plants, as a protection against plant stem destruction, such as by fire.

ligule: a thin outgrowth at the junction of a leafstalk and leaf in a grass or sedge. The ligule is at the junction of the blade and sheath of a leaf.

limestone: a sedimentary rock, largely comprising calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Many limestones are the compressed remnants of marine organisms, such as coral and foraminifera.

Linnaeus: a long-accepted biological classification system proposed by Carl Linnaeus in the mid-18th century.

lipid: a broad group of relatively complex nonpolar carbon-based compounds, used for organic energy storage and a wide variety of biological functions.

liquid: a fluid that flows freely. Water is a liquid.

lithosphere: the outermost shell of a rocky planet. Earth’s lithosphere comprises its crust and upper mantle: the portions that behave elastically over geological expanses of time.

littoral zone (aka nearshore): the area close to shore of a river or body of water.

lizard: a scaled reptile of over 5,600 extant species in all continents except Antarctica, including most oceanic islands.

lobe-finned fish (Sarcopterygii): a clade of bony fish with fleshy, lobed, fin pairs, joined to the body by a single bone. Each fin is on a scaly stalk extending from the body. Contrast ray-finned fish.

lobster: a large marine crustacean in the Nephrophiae family, with 5 pairs of legs, a long body and muscular tail. Lobsters are found in all oceans, residing in burrows or crevices on the sea floor. Lobsters may live 40–60 years, possibly more.

locust: a short-horned grasshopper that has a swarming phase. Several grasshopper species go locust on all continents except North America and Antarctica. The desert locust (Schistocerca gregaria) is best known: swarming in north and west Africa, the Middle East, and the Indian subcontinent. The migratory locust (Locusta migratoria) swarms in Africa, Asia, Australia, and New Zealand.

logogram: a symbol representing a word or its portion.

longclaw: a small, ground-dwelling, insectivorous, African passerine in the Macronyx genus. Compare meadowlark.

longwing (aka heliconian): a colorful butterfly in the Heliconius genus, distributed throughout the tropics and subtropics of the New World, as far north as the southern United States.

lung: the essential respiration organ in air-breathing animals.

lungfish (aka salamanderfish): a freshwater fish that can breathe air.

Luzon: a northern island of the Philippines, the largest.

Lyme disease: an infectious disease caused by the pathogenic bacteria Borrelia burgdorferi, which are carried by Ixodes ticks. A rash that looks like a bull’s eye is an early symptom. Left untreated, the disease can debilitate the joints, heart, and central nervous system.

lysis: viral reproductive release by cell wall rupture: killing the host cell in a violent outburst that releases a multitude of offspring. Contrast lysogeny.

lysosome: the organelle in animal cells responsible for autophagy.


macrobe: an organism larger than a microbe.

macroevolution: origin of new species and evolutionary trends among related species. Contrast microevolution.

macrophage (derived from the Greek for “large eater”): a type of phagocyte employed in vertebrate immune system defense.

Madagascar: a large island in the Indian Ocean off the coast of east Africa.

mafic: silicate mineral rich in in magnesium and iron. Basalt is a mafic rock. Mafic is a portmanteau of “magnesium” and “ferric” (referring to iron). Mafic rocks are 45–55% silica. Contrast felsic.

magma: molten rock made underground. Igneous rocks come from cooled magma.

magnesium (Mg): the element with atomic number 12; an alkaline earth metal; the 8th most abundant element in Earth’s crust.

magnetoreception: sensory reception of the Earth’s magnetic fields by biochemical means.

malaria: a mosquito-borne infectious animal disease caused by the parasitic protozoan Plasmodium falcipanum.

Malay Archipelago: the archipelago between mainland Indochina and Australia, comprising over 25,000 islands.

mallard: a dabbing duck native to the temperate and subtropical Americas, Eurasia, and North Africa, and has been introduced elsewhere. Dabbing ducks are a subfamily (Anatinae) of the family Anatidae, which includes ducks, geese, and swans. Drakes have a glossy green head, and gray on their wings and bellies, whereas the hens have mainly brown-speckled plumage.

mammal: a class of air-breathing vertebrate animals, characterized by endothermy, hair, and females with mammary glands.

mandible: jawbone (the lower jaw in mammals).

mangrove: various salt-tolerant (halophyte) trees that grow in coastal biomes in the tropics and subtropics.

manipularity: the ease with which an organism can manipulate its environment.

manipularity–intelligence hypothesis: a hypothesis by Ishi Nobu that the ease by which organisms can manipulate their environment is inversely related to acumen as a life-history variable.

Maniraptora: a clade of dinosaurs that begat birds and non-avian species.

manta ray (aka devil ray): a large ray in the Manta genus. Mantas are found near in warm marine waters. Many manta species migrate across open oceans singly or in groups, though at least 1 is resident and coastal.

mantis (plural: mantises or mantes): an order of tropical and temperate insects, with over 2,400 species in 430 genera. The closest relatives to mantes are cockroaches and termites.

mantis shrimp (aka stomatopod): a worldwide marine shrimp of around 400 species, typically solitary and aggressive. Mantis shrimp sport powerful claws which can spear, stun, or dismember prey. The ancient Assyrians called mantis shrimp “sea locusts.”

mantle: the layer of Earth above the core and below the crust.

mantle plume: the rising of hot rock from the core-mantle boundary through the mantle to become a diapir (intrusion) in the Earth’s crust.

marbled crayfish (aka marmokreb, Procambarus virginalis): a small (4–8 cm) freshwater crayfish, unique among decapods in being parthenogenetic. The marbled crayfish prefers warmer waters – cold waters kill. Unlike some other crayfish, marmokrebs do not burrow. Discovered in German pet stores in the late 1990s and let loose by pet owners, wild established populations are usually found in urban semi-natural water bodies.

Markov property: the memoryless property of a stochastic process, termed after Russian mathematician Andrey Markov. A Markov process depends only upon the present state, with no reference to antecedents.

marmoset (aka zari): a small New World monkey of 22 species in 4 genera.

marsupial: a clade of mammals characterized by giving birth to relatively undeveloped live young. An infant marsupial (joey) develops within its mother’s pouch.

mass extinction: the indiscriminate extinction of many species during an extinction event. Contrast background extinction.

mastodon (26.8 MYA–11 TYA): an elephant-like animal hunted to extinction by humans.

matamata turtle: a freshwater turtle native to South America, primarily the Amazon and Orinoco basins. Matamata are carnivorous, feeding exclusively on fish and aquatic invertebrates. Matamata swallow prey whole, as their mouth is not built for chewing.

materialism (economics): the belief that human prosperity is based upon material possessions, upon which value can be ascribed.

Matryoshka doll: a set of hollow wooden dolls of decreasing size which can be placed one inside another.

matter (physics): something with mass, constructed of fermions. See energy.

matterism (aka (philosophical) materialism): the monistic belief that reality is made of matter. Matterism ignores that matter of made of energy and supposes that the mind is a figment of something substantial. Contrast energyism.

Maya: an ancient people inhabiting Mesoamerica (central America). The earliest Mayan villages and agriculture date to ~1500 bce.

meadowlark: a group of New World grassland birds comprising 7 species. Meadowlarks are largely insectivorous. Male meadowlarks have a black or brown back, and extensively yellow or red underparts. Compare longclaw.

mechanical isolation (evolutionary biology): reproductive incompatibility between a species and its descendant.

Mediterranean basin: the terrestrial region around the Mediterranean Sea that has a Mediterranean climate of mild, rainy winters and hot, dry summers.

Mediterranean Sea: the sea connected to the Atlantic Ocean and enclosed by the Mediterranean region of southern Europe and western Anatolia, north Africa, and the Levant.

megafauna: large animals.

Megalomyrmex: a genus of ant that are social parasites of attine ants.

megaphyll: a leaf with multiple veins. Contrast microphyll.

meiosis: the special cell division for sexual reproduction, producing germline gametes (sperm or eggs). Meiosis also refers to the cell division process for making spores. Compare mitosis.

Melanesia: a somewhat ill-defined subregion of Oceania, extending from New Guinea to Fiji, comprising most of the islands immediately north and northeast of Australia.

melanin: a group of pigments found in most organisms.

melyrid beetle: a tiny beetle (up to 1 cm) noted for its toxicity.

membrane (cytology): a lipid bilayer surrounding a cell, providing a barrier between the cell and the outside world.

Mendelian inheritance: biological inheritance following laws proposed by Gregor Mendel.

menopause: the transitional period in vertebrates of reproductive senescence some time before natural death; typically occurring in women between 45–55 years of age.

mentation: mental activity.

mentotype: the psychological constitution of an organism, including cognitive orientations and capacities, awareness loci, and worldview. Compare phenotype.

Merced clarkia (Clarkia lingulata): a rare evening primrose endemic to California; now endangered, owing to herbicide use.

meristem: plant tissue where growth occurs.

mesocarp: the middle layer of a pericarp, comprising the pulp of a fruit.

mesoglea: a non-living jelly, sandwiched between 2 thin (single cell) layers of epithelium, which functions as a hydrostatic skeleton.

mesohyl: the gelatinous matrix within a sponge that resembles connective tissue.

Mesolithic (20–5 TYA): the final period of foraging in human cultures as the predominant lifestyle, before giving way to agriculture, between the Upper Paleolithic and Neolithic; 20–8 TYA in southwest Asia, 15–5 TYA in Europe.

Mesopotamia: an area of the Tigris–Euphrates river system, widely considered the Western cradle of civilization during the Bronze Age. Indigenous Sumerians, Assyrians, and Babylonians were there at the onset of written history 3100 bce.

mesotherm: an animal with internal means to raise body temperature, but not with the precision of maintaining thermal homeostasis like endotherms. See ectotherm, endotherm.

Mesozoic (252–66 MYA): the geological era – called the Age of Reptiles by Gideon Marshall – which includes the Triassic, Jurassic, and Cretaceous periods.

messenger RNA (mRNA): an RNA molecule with the physical blueprint for a protein product.

metabolic pathway: a series of chemical reactions within a cell, typically with an intended biological end-product.

metabolism: cellular chemical reactions which provide energy for vital processes. See anabolism, catabolism.

metabolite: a product of metabolism.

metamerism: a plant or animal with a body comprising a linear series of segments, similarly in structure. Earthworms and centipedes are metameric.

metamorphic (rock): a rock arising from transformation via heat and pressure. The original rock (protolith) may be igneous, sedimentary or a previous incarnate metamorphic. Compare igneous, sedimentary. See basement.

metamorphism (geology): the recrystallization of a rock owing to heat, pressure, or chemically active fluids.

metamorphosis: conspicuous and relatively abrupt changes in phenotype during the life cycle of an animal, usually accompanied by a change in habitat and/or behavior. Some insects, mollusks, amphibians, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis. The 3 types of metamorphosis are ametabolous, hemimetabolous, and holometabolous.

metaplasia: a reversible transformation of one differentiated cell type to another.

metazoan (plural: metazoa): an animal.

meteorite: a sizable rock from space that managed to smack Earth’s surface without being vaporized on atmosphere entry. A meteorite might be a comet or asteroid.

methane (CH4): a flammable, explosive gas. Methane forms in mashes and swamps from decaying organic matter.

methanethiol (CH4S): a breakdown product of the algal metabolite dimethylsulfoniopropionate.

methanogen: an anoxic archaeon that produces methane as a metabolic by-product.

methanogenesis (aka biomethanation): waste formation of methane by methanogens.

Methanospirillum hungatei: an ancient methogenic archaeon. Commonly employed nowadays to clean up wastewater.

metoposaur: an extinct family of amphibians that arose during the Triassic; a trematosaurian temnospondyl. Though no relation, metoposaurs somewhat resembled crocodiles.

microbe: a microorganism, typically single-celled. Microbes include archaea, bacteria, protists, and fungi. Contrast macrobe.

microbial loop: recovery of otherwise lost organic energy by bacteria.

microbiome: the endosymbiotic, microbial community that comprises every eukaryotic organism, especially multicellular eukaryotes. Commensal prokaryotic inhabitants are essential to eukaryotic life.

microevolution: changes within species. Contrast macroevolution.

microphyll: a leaf with a single, unbranched vein. Contrast megaphyll.

Microraptor: a genus of small, 4-winged bird-like dinosaurs.

Middle Ages (aka Medieval period) (~467–1400): the period of European history between the 5th and 15th centuries, beginning with the collapse of the Roman Empire and the onset of the Dark Ages.

Milankovitch cycle: a 1920 hypothesis by Milutin Milanković relating changes in sunlight, and thereby climate, to variations in Earth’s orbit about the Sun. Earth has an elliptical orbit, with eccentricities in that orbit, as well in its axial tilt and precession (rotational orientation). Milankovitch cycles are now used extensively to explain the timing of glacial-interglacial cycles in Earth’s evolution.

militarism: subordination of civil society to the military as a virtuous ideal.

milk: a fluid secreted by female mammary glands for nourishment of their young offspring; also used for a liquid resembling milk, including the juice of a coconut, the latex of a plant, or the fluid contents of an unripe grain kernel.

milkweed: an herbaceous perennial dicot of over 140 known species in the Asclepias genus, native to North America. Milkweeds are among the most complex flowers, comparable to orchids.

milkweed butterfly (subfamily Danainae): a brush-footed butterfly that lays its eggs on milkweeds, upon which their larvae feed. There are ~300 danaine butterfly species worldwide, found mostly in tropical Asia and Africa.

milt: the seminal fluid of fish, mollusks, and other water dwellers, who reproduce by spraying milt, which is loaded with sperm, onto roe (fish eggs).

mimesis: camouflage toward triviality.

mimicry (biology): trait imitation by a species.

Minoan (civilization) (~2800–1420 bce): an Aegean Bronze Age civilization flourishing on the island of Crete until overrun by the Mycenaeans from mainland Greece.

mimivirus: a genus (Mimivirus) of giant viruses that infects amoebae.

mind: an intangible organ for symbolic processing.

Miocene (23–5.3 MYA): the 1st of 2 epochs in the Neogene period, divided into 6 ages with corresponding rock stages.

mite: a tiny arthropod in the subclass Acari, along with ticks. With 48,200 described species, mites are among the most diverse and successful invertebrates, having adapted to a vast array of habitats: living free in water or soil, and as parasites on plants, animals, and even mold. Studying ticks and mites is acarology.

mitochondrion (plural: mitochondria): an organelle that acts as the cell’s power plant, generating ATP.

mitosis: the eukaryotic cell division process. Compare meiosis.

mitotic recombination: a relatively rare genetic recombination that occurs in somatic cells during mitosis.

moa: a large flightless bird endemic to New Zealand; the dominant herbivore there until hunted to extinction by men in the late 13th century. The 2 largest species reached 3.6 meters in height and weighed up to 230 kilograms.

modularity (biology): an organic system organized into identifiable units. Modularity appears at all biological scales, from macromolecules to organs and body plans.

moiety: a small molecule of a chemical functional group.

mold (aka mould): a fungus that grows as multicellular filaments (hyphae). In contrast, fungi that grow as single cells are called yeast.

molecule: a combination of 2 or more atoms.

mollusk (aka mollusc): a phylum of invertebrates. Mollusks are highly diversified in marine environments, comprising 23% of identified macroscopic marine species. There are also freshwater and terrestrial mollusks, such as snails.

Molyneux’s problem: a philosophical question concerning the basis of knowledge and the senses: would a blind person be able to instantly recognize by sight what previously had been known only by touch if vision were restored?; posited by William Molyneux in 1688 to John Locke.

mongoose (plural: mongooses or mongeese): a small carnivore of 33 extant species, endemic to parts of southern Eurasia and Africa.

monitor lizard: a large, venomous, carnivorous lizard in the Varanus genus, with ~79 species, native to Africa, Asia, and Oceania.

monkey: a primate, excluding apes.

monkey-flower (aka musk-flower): a flowering plant of 150 species in the genus Mimulus. Monkey-flower species diversity is greatest in western North America, with Australia another area of considerable diversity.

monochromacy: having a single type of vision receptor. Marine mammals, with only 1 color cone type, are monochromats, as are night monkeys. Compare dichromacy, trichromacy, tetrachromacy.

monocot (monocotyledon): a plant with 1 embryonic leaf (cotyledon) in its seed. Compare dicot, eudicot.

monoecy: the presence of male and female flowers on the same plant. Compare hermaphrodite.

monogamy: the practice of having a single mate; a mating system comprising a male and female pair. Contrast polygamy.

monogenesis: the false hypothesis by Charles Darwin that all human races descended from a single species.

monomer: a molecule that may bind with other molecules to form a polymer.

monophyletic: organisms descended from a single taxon; a clade.

monosaccharide (aka simple sugar): a simple carbohydrate with the formula (CH2O)n, where n = 3 (triose), 5 (pentose), or 6 (hexose). Glucose, fructose, and ribose are exemplary monosaccharides. See disaccharide.

montane: an ecosystem found in mountains, stratified by elevation.

morpheme: the smallest semantic language unit.

morphogenesis: biological development of form.

morphology: the form and structure of an organism or other system. Compare physiology.

mosaic evolution: an evolutionary change in only part of an organism.

mosasaur: an extinct group of large marine reptiles, of 38 genera, which lived from the Early Cretaceous until the period’s end 66 MYA.

mosquitofish: a small freshwater fish in the Gambusia genus.

moth: a flying insect related to the butterfly. Most moths are nocturnal. ~160,000 species are extant. Compare butterfly.

motile: capable of movement. Contrast sessile.

motion camouflage: movement that does not attract the attention of an intended target (typically a prey or predator).

Mousterian (industry): Middle Stone Age tool technology which represented refinements from Acheulean culture. Mousterian was named after an archeological site at Le Moustier, a rock shelter in the Dordogne region of France.

mudskipper: an amphibious fish in the goby family that walks through the mud on its pectoral fins.

mulberry (aka fig): an angiosperm of over 1,100 species in ~38 genera. See fig.

mule: a hybrid between a male donkey and a mare (female horse). Compare hinny.

Müllerian mimicry: poisonous species that share a common predator mimicking each other’s warning signals. The mimicry need not be visual: it may be any sense that a predator employs to select its prey. Named after its discoverer, Fritz Müller.

multicellularity: an organismal structure comprising multiple cells. Contrast pluricellularity.

multituberculate: a group of rodent-like mammals that lived 165–35 MYA.

murre (aka guillemot (UK), turr (Canada)): a large black-and-white diving auk that spends most of its life over northern coastal seas, only venturing onto land for colonial breeding. There are 2 species in the murre genus (Uria): the common murre (U. aalge) and the thick-billed murre (U. lomvia).

muscovite: a mineral high in aluminium and potassium.

mussel (aka clam): a bivalve mollusk.

mutation: a change in a genetic sequence.

mutualism: regular interaction between 2 organisms that provides mutual benefits.

MYA: millions of years ago.

Mycenaean (civilization) (1600–1100 bce): an ancient civilization during the Late Bronze Age. Mycenae is the historical setting for much ancient Greek literature and myth, including the epics of Homer.

myoelastic-aerodynamic theory: a theory of vocalization corresponding with Bernoulli forces (negative pressure) on elastic tissue folds muscularly controlled (myo refers to muscles).

myosin: an ATP-dependent motor protein, best known for its role in muscle contraction, but involved in a wide range of eukaryotic motility actions.


naïve empiricism: the belief that the knowledge can only be gained through empirical examination of Nature.

naïve realism (aka direct realism, commonsense realism): the belief that perception of actuality is reality, objectively and without bias.

Nanuqsaurus: a genus of carnivorous tyrannosaurid theropod, adapted to a cool climate.

narwhal (aka narwhale): a medium-sized toothed whale with a large tusk from a protruding canine tooth. Narwhals live year-round in Arctic waters.

native (biology): naturally occurring and associated with a certain environment or biome. Compare indigenous, endemic.

Natufian culture: a pre-agricultural sedentary culture in the Levant 15–12 TYA.

natural genetic engineering: adaptive genomic restructuring, including epigenetic modifications.

natural genetic engineering toolkit: the total set of tools that every cell has to restructure its genome.

natural philosophy: the study of Nature from a holistic perspective; the common methodology of comprehending Nature until the 17th century, before modern science barged in with its strictly empirical scientific method. See natural science. Contrast science.

natural science: natural philosophy coupled to the scientific method.

natural selection: a meaningless term acclaiming Darwinism, popular among religious evolutionary biologists who should know better. See Darwinism.

Nature: the exhibition of existence. See coherence.

nautiloid: a diverse group of marine cephalopods with hard outer shells for protection, such as the nautilus. Nautiloids arose during the Late Cambrian. Compare coleoid.

nautilus: a pelagic marine nautiloid that emerged during the Late Cambrian, with 6 extant species in 2 genera.

Nazca Plate: an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America.

Neanderthal (aka Neandertal) (~800–45 TYA): an extinct species in the Homo genus, closely related to modern humans.

Near East: a geographical area of southwest Asia and northeast Africa. The term has generally been applied as being the area of the Ottoman Empire at its apogee in the mid-1500s. Since the mid-1900s, the terms Near East and Middle East have been approximated as synonymous.

near passerine: an arboreal bird, related to (true) passerines. Near passerines include cuckoos, swifts, hummingbirds, woodpeckers, toucans, hornbills, kingfishers, nightjars, mousebirds, trogons and quetzals. A comprehensive listing is somewhat controversial, as some birds, such as pigeons and parrots, were traditionally considered near passerines, but their inclusion is no longer generally accepted.

Nearctic: organisms indigenous to North America before the Great American Interchange. Contrast Neotropic.

necrosis: premature cell death in living tissue via autolysis. Compare apoptosis.

nectar: a sugar-rich solution produced by plants as a bribe for pollinators.

nectarivore: an animal that eats primarily or exclusively nectar. Most nectarivores are insects or birds but there are also nectarivorous geckos, bats, and the tiny honey possum.

negligible senescence: lack of aging symptoms.

nematode: see roundworm.

nematocyte: a barb with chemical sting.

neochrome: a protein photoreceptor that is active at low light levels by its responsiveness to longer wavelength light. Neochrome is a synthesis of phytochrome and phototropin. See chlorophyll, cryptochrome, phototropin, phytochrome.

Neogene (23–0.05 MYA): the middle geological period of 3 in the Cenozoic era, during which mammals and birds evolved into their modern forms. Later in the period hominoids arose.

Neolithic (aka New Stone Age) (10,200 bce–[4500–2000] bce): a technological era in human prehistory marked by the development of metal tools and by the domestication of crops and animals; coined by Charles Lyell in 1965.

neonate: a human infant within 28 days of birth.

Neoproterozoic (1 BYA–542 MYA); the 3rd and last era of the Proterozoic eon.

neoteny (aka juvenilization, pedomorphosis): retention by adults of traits previously seen only in the young (in the perspective of evolutionary descent). See heterochrony.

Neotropic: organisms indigenous to South America before the Great American Interchange. Contrast Nearctic.

Neotropics: tropical Central and South America.

Neptune grass (aka Mediterranean tapeweed, Posidonia oceanica): a long-lived seagrass endemic to the Mediterranean Sea.

nerve (cell): see neuron.

nervous system: the electro-chemical communication system of an animal via nerve cells. Nervous systems emerged 600–550 MYA.

nettle: a flowering plant with stinging hairs in the Urtica genus.

neuron (aka nerve cell): an electrically excitable intercellular signaling cell as part of the nervous system, employed for sensory or motor communication. Functionally, neurons are managed by glia.

New World: the Western Hemisphere, specifically the Americas and nearby islands; sometimes Oceania is included. The term originated in the early 16th century by European explorers expanding their worldly horizons. Contrast Old World.

niche (biology): a certain set of ecological features that provide for occupation by an adapted specialist species.

niche differentiation (aka niche partitioning, niche segregation, niche separation): the evolutionary process of similar species that might otherwise compete adapting to different patterns of resource use (typically food).

nickel (Ni): the element with atomic number 28; a silvery-white lustrous metal with a subdued golden tinge. On Earth, nickel is always found combined with iron, both of which originate from supernova nucleosynthesis.

nitrogen (N): the element with atomic number 7; a colorless, tasteless, odorless element that, as a diatomic gas (N2), is relatively inert.

nitrogen fixation: fixing atmospheric nitrogen gas into a biologically employable form; the process by which diatomic nitrogen gas is converted to ammonium ions which can be employed by plants. Only certain microbes have mastered the trick of fixing nitrogen.

nocturnal (biology): active at night. Contrast diurnal. See crepuscular.

node (botany): a junction between plant parts; typically, the point of attachment of a twig or leaf on the stem of seed plants.

non-homologous end joining: a pathway for repairing a DNA sequence break when no homologous copy exists.

non-homologous recombination: exchanging nucleotide sequences between dissimilar genes. Contrast homologous recombination.

Nothosauroidea: an order of Triassic marine sauropterygian reptiles that lived the lifestyle of today’s seals.

notochord: a flexible rod-shaped body; more particularly, a cartilage back support. The notochord later evolved into the backbone.

nucleic acid: an acidic biomolecule comprising a nucleotide, discovered by Friedrich Miescher in 1869. DNA and RNA are nucleic acids.

nucleobase: a nucleic-acid base; a nitrogen-based, ring-shaped molecule that comprises the basic building block of nucleotides.

nucleoid: an irregularly shaped region within a prokaryotic cell containing a single genophore.

nucleotide: an individual structural (monomer) unit of nucleic acid (DNA, RNA); a nucleobase packaged with sugar and phosphate groups, held together by ester bonds.

Nuna (aka Columbia): a supercontinent created 1.9 BYA. Nuna began breaking up 1.5 BYA.

Nyasasaurus (from 243 MYA): a genus of 2–3-meter long reptiles that presaged dinosaurs.

nymph: an immature hemimetabolous insect. Nymphs roughly resemble adults, albeit with distinctive body proportions, size, and color patterns. Compare larva.


obligate: obligatory.

ocean: a large, deep body of saltwater.

ocean conveyor belt: the continuous global system of interconnected ocean currents. This conveyor belt system affects climate worldwide.

Oceania: a region centered on the islands in the tropical Pacific Ocean, including Australasia.

octopus (plural: octopuses, octopi, or octopodes): a highly intelligent cephalopod.

Old World: Africa, Europe, and Asia; the part of the world known to Europeans prior to their sojourns to the Americas. Contrast New World.

Older Dryas (stadial): a 100–150-year stadial centered around 14.1 TYA, its coldest time.

Oldowan (industry): the earliest known Stone Age tool technology (2.6–1.7 MYA). Named after Olduvai Gorge, where many artifacts were found by Louis and Mary Leakey during the 1930s. See also: Acheulean, Mousterian industries.

Olduvai Gorge (aka Oldupai Gorge): a rift in east Africa that is one of the most important paleoanthropological sites in the world.

olfaction (aka oflactics): the act or sense of smell.

Oligocene (34–23 MYA): the 3rd and last geologic epoch in the Paleogene period; characterized by a sparsity of new mammals after a speciation burst during the preceding Eocene epoch. Global changes during the Oligocene include expansion of grasslands and a regression of tropical forests toward the equatorial belt.

oligosaccharide: a saccharide (sugar) polymer, typically with 2 to 10 component simple sugars (monosaccharides).

olivine ((Mg+2, Fe+2)2SiO4; aka peridot, chrysolite): a magnesium iron silicate mineral, common in Earth’s asthenosphere, but which weathers quickly on the surface.

ommatidium (plural: ommatidia): a facet of a compound eye comprising 1 or more photoreceptor cells innervated by a single axon, providing a single picture element.

omniscience: (the idea of) having comprehensive awareness and comprehension of Nature. Compare knowledge.

omnivore: an organism that consumes both plant and animal matter as primary food sources. Compare herbivore, predator, saprovore.

On the Origin of Species (1859): the 1st book by Charles Darwin, on evolution.

There is a frequently recurring struggle for existence, it follows that any being, if it varies however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. ~ Charles Darwin

ontogeny: the course of development in an organism.

Oort cloud: a hypothesized cloud of comets nearly a light-year from the Sun. The outer edge of the Oort cloud defines the cosmographical boundary of the solar system, where Sun’s gravity holds sway.

opah (aka moonfish, sunfish, kingfish, Jerusalem haddock): a large, colorful, pelagic, lamprid fish in the Lampris genus.

opportunistic evolution: the theory that evolution adaptively takes place opportunistically.

opossum (colloquially possum): a marsupial indigenous in the western hemisphere. Opossums are biological generalists, and so successful colonizers. There are 103+ opossum species in 19 genera.

opsin: a light-sensitive protein found in the photoreceptor cells of an eye’s retina.

orangutan: a red-haired ape; the largest arboreal ape.

orca (Orcinus orca): the largest oceanic dolphin.

Ordovician (485–443 MYA): the 2nd of 6 periods in the Palaeozoic era, following the Cambrian period and preceding the Silurian. The name derives from the Celtic tribe of the Ordovices in Wales, from where rocks of the period were first taken for study.

organelle: a subunit within a eukaryotic cell with a specialized function. Organelles are membrane-bound. Cell organelles evolved through endosymbiotic union with a host cell. An organelle is a former endosymbiont, before it irrevocably joined the team.

organism: a life form; an animated organic structure.

organitype: the paradigms which constitute an organism: the combination of phenotype, mentotype, and genotype.

oribatid (aka moss mite, beetle mite): an order of mites with low metabolic rate, slow development (several months to 2 years), low fecundity, and considerable longevity (up to several years), in the Acari group.

Ornithomimidae: a group of beaked theropods which looked somewhat like modern ostriches.

Ornithischia: an order of beaked, herbivorous dinosaurs.

ornithology: the study of birds.

Ornithoscelida: the clade of dinosaurs including ornithischians (Ornithischia) and theropods (Therapoda). See Saurischia.

Ornithurae: the clade which includes the common ancestor to all modern birds.

orogen: a mountain belt formed from compressive deformation of a tectonic plate.

orogeny: the process of forming orogens; mountain making.

Orrorin (6.2–5.6 MYA): a genus of early hominin with anatomy closer to humans than later hominin Australopithecus afarensis. Orrorin had a precision grip much like modern humans.

orthogenesis (aka orthogenetic evolution, autogenesis): a hypothesis that organisms have a goal-directed (teleological) vector of evolution; introduced by Wilhelm Haacke in 1893 and popularized by Theodor Eimer; now considered moribund.

orthorhombic crystal system: one of the 7 crystal systems. Orthorhombic lattices comprise a rectangular prism, with base (a by b) and height (c) such that a, b, and c are distinct. All 3 bases intersect at 90° angles, rendering the 3 lattice vectors mutually orthogonal.

Osiris: the ancient Egyptian god of the underworld, the afterlife, and rebirth. See Set.

osmolyte: a chemical compound affecting osmosis.

osmophile: an organism capable of growing in a sugary habitat.

osmosis: the net movement of solvent molecules through a partially permeable membrane into a region with higher solute concentration, to effect an equalized solute concentration on both sides of the membrane. Osmosis relies upon kinetic energy.

osmotic pressure: the pressure needed to prevent inward water flow across a semipermeable membrane.

ostracod (aka seed shrimp): a class of small crustaceans of some 70,000 species.

Ottoman Empire (1299–1922): an empire founded by the Turks upon their conquest of Constantinople (1453), thus overthrowing the Byzantine Empire.

Ouranopithecus (9.7–7.2 MYA): an early hominid with a large, broad face, showing a mixture of ape and human traits (based upon cranial fossils). Ouranopithecus was probably a quadruped. The hominid identified by 3 teeth as Graecopithecus (7.2 MYA) may have been an Ouranopithecus.

outcrossing (aka outbreeding): crossing between breeds – a practice which increases genetic diversity.

ovary: the egg-producing reproductive organ.

ovary (botany): the enlarged lower part of the pistil on flowers, enclosing ovules, which develop into seeds once fertilized. Such floral ovaries mature into fruit.

ovary (zoology): a vertebrate ovum-producing reproductive organ.

oviparity: egg laying. Contrast viviparity.

ovipore: a pore-like sex organ of a female animal, typically an insect, in which spermatophores are inseminated.

oviraptorosaur: a feathered maniraptoran dinosaur that lived during the Cretaceous.

ovule: the plant part that contains the female germ cell which develops into a seed.

oxpecker: a bird clade of 2 species endemic to the savanna of sub-Saharan Africa. Oxpeckers sit on the backs of large animals, feeding on parasites. Oxpeckers prefer certain grazing species, avoiding others.

oxygen (O): the element with atomic number 8; a highly reactive nonmetallic element that readily forms compounds (notably oxides) with almost all other elements.

oxytocin (C43H66N12O12S2): a neurohypophysial hormone that acts in the brain as a sensation modulator. Oxytocin has various effects in different animal species. In primates, oxytocin is instrumental in facilitating social bonding.

ozone (O3, aka trioxygen): a triatomic molecule comprising 3 oxygen atoms. O3 is less stable than O2 (dioxygen). Ozone is formed by ultraviolet radiation of dioxygen.


Pacific Ring of Fire: a seismic belt of geological hot spots that runs from north of New Zealand up through Indonesia, Japan, and the Aleutian Islands, then down the west coast of the Americas, ending in Southern Chile.

Paleo-Tethys Ocean: a tropical ocean, extant from the Late Carboniferous period into the Triassic, located where the Indian Ocean and Southern Asia are now.

paleoanthropology: the study of hominids from physical evidence. Paleoanthropology combines paleontology and anthropology.

paleoatmosphere: the atmosphere before life arose.

Paleocene (66–56 MYA): the 1st of 3 epochs in the Paleogene period, after the Cretaceous–Paleogene (K–Pg) mass extinction event.

Paleocene–Eocene Thermal Maximum (petm, 55.8 MYA): a period of rapid global warming.

Paleogene (66–23 MYA): the 1st of 3 periods in the Cenozoic era.

Paleolithic (2.6 MYA–11,700 ya): the prehistoric cultural period of human history, beginning with the development of the most primitive stone tools, roughly 2.6 MYA. The Paleolithic corresponds with the Pleistocene epoch.

paleontology: the study of prehistoric life.

paleosol (geology): soil preserved by burial.

Paleozoic (541–252.2 MYA): the earliest and longest of the 3 eras of the Phanerozoic eon, beginning with the Cambrian period, and ending with the Permian.

Panagrolaimus davidi: an Antarctic nematode, known to bear the horrid chill if well fed and not too old.

Panama Flow: a surface ocean current that flows southwestward from the Central American coast.

pancrustacea: the clade comprising crustaceans and hexapods.

Pangea (aka Pangaea): the supercontinent that contained most of Earth’s land mass 300–200 MYA. The global ocean of the time was Panthalassa. Pangea broke up into Laurasia to the north and the southern Gondwana.

pangenesis: an ancient hypothesis of holistic heredity via an atomic biological mechanism. Charles Darwin proposed a pangenesis in which each part of a body continually emitted gemmules, which were tiny organic particles that aggregated in the gonads, contributing heritable information to gametes.

Pannotia (610–550 MYA): the largely southern supercontinent that broke into 4 major landmasses.

Panthalassa: the global ocean that surrounded Pangea.

pantheism: the belief that Nature includes an immanent God. Compare supremism.

paper wasp: a wasp in the genus Polistes that makes its nest out of thin, paper-like sheets. The North American paper wasp (P. metricus) does so alone. In contrast, the golden paper wasp (P. fuscatus) creates a communal nest with other females.

pappus (plural: pappi): a tuft-like appendage to the achene of certain plants.

paracrine signaling: intercellular communication over a short distance. Compare juxtacrine signaling, endocrine signaling.

Paradoxides: a genus of relatively gigantic trilobites found throughout the world during the mid-Cambrian.

paragenital: a pseudo-genital.

parallel evolution: selfsame trait evolution in organisms of distinct clades where an antecedent similarity can be established genomically. Compare convergent evolution.

parallelism (evolutionary biology): adaptation that reveals itself over time; alternately, environmental tolerances that characterize generalism.

paramecium (plural: paramecia): a unicellular ciliate, widespread in all watery habitats, including brackish water.

páramo: an alpine tundra ecosystem in the northern Andes mountains; possibly the fastest evolutionary ecosystem in the world.

Paranthropus (2.7–1.2 MYA): a genus of robust, bipedal hominid, with considerable sexual dimorphism, and a brain similarly sized to modern chimpanzees. Paranthropus had a precision grip.

parapatric speciation: speciation by preference in populations in nearby habitats which are not physically separated. Compare allopatric speciation, sympatric speciation.

parapatry: a relationship between organism populations with adjacent ranges with little (but some) overlap. Compare allopatry, sympatry.

parasite: an organism living in, on, or with another organism, obtaining benefits that usually reduces the fitness or health of its host.

parthenocarpy: (a plant) producing fruit without fertilization of ovules. Plants sometimes use parthenocarpy as something of a ruse. Seedless wild parsnip fruit are preferred by certain herbivores, thus acting as a decoy defense against seed predation. Other plants produce extra fruit without seeds to keep seed-dispersing animals from starvation or migration.

parthenogenesis: asexual reproduction where an unfertilized egg cell nonetheless develops into an embryo. Sperm or pollen may trigger embryonic development without making a genetic contribution. In animals, parthenogenesis means an embryo developing from an unfertilized egg. From the Greek for “virgin birth.” Contrast heterogamy. See gynogenesis.

passerine (bird): a bird in the Passeriformes order, comprising over half of all bird species (over 5,000 identified species in over 110 families). One of the most diverse terrestrial vertebrate orders, around twice that of the large mammal order: rodents. Passerines include most perching birds, such as sparrows, wrens, finches, tits, and corvids. Birds that sing are passerine.

passive margin: a transition area between oceanic and continental crust, absent an active plate margin. Contrast active margin.

pathogen: an infectious agent, commonly called a germ; a microorganism that causes diseases in its host, including certain viruses, bacteria, fungi, and prions.

patrilocality: a social system where mates live in the male’s natal community.

PCB (polychlorinated biphenyl–C12H10-xClx, where x = 1–10): a synthetic organic compound of chlorine attached to biphenyl – a molecule with 2 benzene rings. There are 130 different PCBs used commercially; all are a persistent, toxic pollutant. Because of its toxicity, PCB production was banned in the US in 1979, and by international convention in 2001. The American legal allowable contaminant level for PCB is zero.

peach (Prunus persica): a deciduous tree native to northwest China.

peacock spider: a jumping spider which owes its name to males’ colorful, iridescent abdomen patterns which are employed in courtship displays.

pelagic (zone): a zone in a body of water that is neither near the shore nor close to the bottom (benthic).

pelycosaur: an informal grouping of basal synapsids.

penguin: a flightless seabird of 17–20 species, living in the southern hemisphere, commonly Antarctica. While many are found in cold climates, several species live in the temperate zone.

penicillin: an antibiotic derived from Penicillium fungi.

penis: the sex organ that males employ to inseminate females via copulation. See vagina.

pennaceous feather: a feather type found in modern birds and some maniraptoriform dinosaurs, comprising a stalk or quill (rachis) with feathered vanes (vexilla) to either side.

peppered moth (Biston betularia): a nocturnal moth that adapts its shading to its resting surface environment.

peramorphosis: an evolutionary change in developmental rates that adds new stages to those in ancestors; typically, extended growth periods.

perceive, perception: mentally integrating sensory input (sensation) using memory. Perception is a 3-stage process: 1) turn a sensation into a symbolic representation, 2) identify sensed symbols using memory and categorization, then 3) derive the meaning of the identified symbols, especially regarding affinity or avoidance. See conceptualization.

perching bird: an arboreal passerine.

Perciformes (aka Percomorpha, Acanthopteri): a class of ray-finned fish; the most numerous order of vertebrates, comprising 41% of all bony fish. Perciformes means “perch-like.”

perennial (botany): a plant that is present aboveground throughout the year, and which lives for more than 2 years. Woody plants, such as shrubs and trees, are perennials. Compare annual, biennial. See herbaceous.

pericarp: the layers of a ripened ovary or fruit, typically comprising 3 layers: exocarp, mesocarp, and endocarp.

peridotite: coarsely granular igneous rock, composed chiefly of olivine with an admixture of various other minerals.

period (geology): a duration in the geological time scale, roughly 100 million years; shorter than an era, longer than an epoch.

Permian (299–252 MYA): the 6th and last period of the Paleozoic era, following the Carboniferous period and preceding the Triassic. The name derives from the ancient Russian kingdom of Permia. Earth at the time had a single supercontinent: Pangea, surrounded by the global ocean Panthalassa. The extensive rainforests of the Carboniferous were gone, leaving vast regions of arid desert in the continental interior. Reptiles, better adapted to dryer conditions, rose to dominance over their amphibian ancestors.

PETA (People for the Ethical Treatment of Animals): a non-profit organization that works against animal suffering, particularly targeting factory farms, the clothing trade, laboratories, and the entertainment industry.

petroleum: a natural yellow-to-black liquid comprising algae, zooplankton, and other organisms crushed, heated, and liquefied. Compare coal.

pH: a measure of acidity which ultimately relates to the number of protons in a solution. 7 = neutral; < = acidic; ▫ = base (alkaline).

phagocyte: an animal cell which protects it host body by ingesting harmful foreign particles, select microbes, and dying or dead cells.

phalarope: a slender-necked shorebird of 3 species in the genus Phalaropus.

Phanerozoic (542 MYA–now): the 4th geological eon, characterized by complex life inhabiting Earth (based upon an outdated assessment), beginning with the Cambrian period.

pharynx: the passageway tube in the throat that is used for both breathing and eating. The pharynx is also instrumental in vocalization.

phenology: biological phenomena that correlate with climatic conditions.

phenotype: the composite visible traits of an organism: physical, physiological, and behavioral. Compare mentotype.

pheromone: a secreted or excreted hormone employed as a communication signal.

Philippines: a country in Oceania comprising ~7,641 islands.

philology: the study of language from written historical sources.

phloem: tissue that distributes sugar-laden sap among a plant. Compare xylem.

Phoenicia (2500–539 bce): an ancient civilization of city-states (like ancient Greece) that originated on the western, coastal part of the Fertile Crescent.

phosphorylation: attaching a phosphoryl group (PO32–) to a molecule. Phosphorylation and dephosphorylation are extensively employed in cellular processes. In eukaryotes, protein phosphorylation is an extremely common genetic post-translational modification. The addition of a phosphate group to a protein that can alter gene expression by altering the proteins involved in building other proteins.

photolysis (aka photodissociation, photodecomposition): chemical decomposition via radiant energy.

photosynthesis: (an organism) converting sunlight into energy.

phototropin: a photoreceptive protein sensitive to blue light. See chlorophyll, cryptochrome, neochrome, phytochrome.

phylesis: the course of phylogenetic development.

phyletic gradualism: the Darwinian notion of gradual (over millions of years) descent by modification via “natural selection.”

phylogeny (evolutionary biology): the evolution of a genetically related group of organisms.

phylum (biological classification) (plural: phyla): the taxon above class and below kingdom. Phylum typically refers to a uniquely identifiable body plan. Ernst Haeckel coined phylum in 1866. See family.

physiology: the physical structures and biomechanics of an organism.

phytochrome: a photoreceptive protein sensitive to red light and temperature which plants employ. See chlorophyll, cryptochrome, neochrome, phototropin.

phytohormone: a plant hormone. Phytohormones regulate plant growth.

phytoplankton (aka microalgae): photosynthesizing aquatic organisms, both marine and freshwater; from the Greek words for plant and drifter. Oceanic phytoplankton is the primary food source, directly or indirectly, of nearly all other marine life.

picogram: 1-trillionth (10–12) of a gram.

pictogram (aka pictograph): a written symbol representing an object. Compare ideogram.

Pierolapithecus: a hominoid that lived 11.9 MYA.

pig: an even-toed ungulate in the Sus genus.

pine: a softwood conifer native to the northern hemisphere, with ~115 species in the Pinaceae genus.

pink salmon: the smallest and most abundant species of Pacific salmon.

pinniped: a diverse group of fin-footed marine mammals, including seals, sea lions, and walruses. Pinnipeds are typically sleek-bodied and barrel-shaped: bodies admirably adapted for an aquatic lifestyle.

pipefish: a small fish related to seahorses, both of which are in the Syngnathidae family (along with seadragons).

pistil (aka carpel): the female part of a flower, acting as a pollen receptor.

pitcher plant: a carnivorous or saprophytic plant in the genus Nepenthes, endemic to the tropical or tropical-montane biomes of the Malay Archipelago, Southeast Asia, and the eastern part of Madagascar.

pitohui: a passerine of 6 species, endemic to New Guinea; noted for its toxic feathers and skin, owing to its ingestion of melyrid beetles.

placoderm: an early, armored, jawed fish that evolved early in the Silurian.

placozoa: a basal invertebrate, 1 mm across.

plankton: a minute organism living in a water column (freshwater or salt) that is incapable of swimming against a current. The term plankton is both singular and plural.

plant: a kingdom of autotrophs, including mosses, ferns, conifers, and flowering plants (angiosperms). The other eukaryotic kingdoms are fungi, animals, and protists.

planthopper: a tiny hopping insect in the Issus genus that lives on vegetation, both residentially and dietarily. Planthoppers feed on phloem.

plasmid: a tiny globule of genetic information (DNA) useful to microbes for horizontal gene transfer.

Plasmodium: a genus of parasitic protozoa. Infection of Plasmodium falcipanum is known as malaria. Compare plasmodium.

plasmodium: an ameboid which congregates to form a slime mold. Compare Plasmodium.

plastid: a double-membrane organelle in algae and plant cells.

pleiotropy: a single gene influencing multiple seemingly unrelated traits.

Pleistocene (2.588 MYA–11,700 ya): the epoch that follows the Pliocene and precedes the Holocene; defined by Charles Lyell for the emergence of modern marine mollusks. The Pleistocene ends with passing of the Younger Dryas cold spell.

Plesiosauria (200 – 66 MYA): a clade of sauropterygians.

Pleurodira: a minority suborder of the turtles. Pleurodires are side-necked turtles that must bend their neck muscles horizontally to pull their necks back toward their shell, as contrasted to cryptodires (hidden-neck turtles), which may pull their heads straight back into their shells. Pleurodirans are endemic to freshwater environs in the southern hemisphere: South America, Africa, and Australia. Contrast Cryptodira.

Pliobates: a hominoid that lived 11.6 MYA.

Pliocene (5.332–2.588 MYA) (aka Pleiocene): the 2nd and last epoch in the Neogene, following the Miocene and preceding the Pleistocene. From the Greek for “continuation of the recent.” Oddly defined by Charles Lyell as being the most recent fossil rock layer.

plumage: the entire feathery covering of a bird.

pluricellularity: the structure of multiple cells aggregating in an organized manner. Biofilms are pluricellular, as are bacterial filaments. Contrast multicellularity.

pluripotency: a stem cell able to differentiate into any cell type.

plutocracy: social stratification controlled by the materially advantaged.

Poaceae: the angiosperm family of grasses.

poikilohydry: an organism lacking a mechanism to prevent desiccation, as it is tolerant of large fluctuations in hydration. Lichen and bryophytes are poikilohydric.

point mutation (genetics): a mutation of a single nucleotide exchanged for another.

poison frog (aka poison-dart frog, poison arrow frog): a diurnal, poisonous frog native to Central and South America, with over 170 species. Many poison frogs have brightly colored bodies with stark patterns which advertise their toxicity (aposematism).

polar bear: a carnivorous bear that lives in the Arctic Circle.

polarization (optics): a state of light in which the radiation exhibits distinct properties in different directions.

pollen (botany): a mass of male microspores (microgametophytes) in a seed plant.

pollinarium (plural: pollinaria): the complete male reproductive structure transporting pollinia.

pollination: the process of transferring pollen, enabling plant fertilization and reproduction.

pollinium (plural: pollinia): a sac of pollen.

polyandry: a mating system of 1 female and 2 or more males. Contrast polygyny.

polygamy: a mating system of having multiple contemporaneous mates. Contrast monogamy. See polyandry, polygyny.

polygyny: a mating system where 1 male mates with 2 or more females. Contrast polyandry.

polymath: a person learned in several fields of study.

polymorphism (biology): the existence of an organism with several form or color varieties.

polyp: an organism with a fixed base, columnar body, and an open end with mouth and tentacles.

polyploidy: cells with more than 2 paired (homologous) sets of chromosomes. Polyploidy is common in ferns and flowering plants. Some animals, such as goldfish, salmon, and salamanders, possess polyploidy. In other animals, polyploidy may result from abnormal cell division.

polysaccharide (aka glycan): a complex sugar-based macromolecule; a derivative of glucose. Compare monosaccharide.

porcupine: the 3rd-largest rodent (behind the capybara and beaver), with a coat of sharp spines; indigenous to the Americas, southern Asia, and Africa. Mostly nocturnal, porcupines are herbivores.

porpoise: any of 6 species of small cetaceans related to dolphins and whales. All porpoises are oceangoing. Most live near shore. The best-known species is the harbor porpoise, found across the northern hemisphere.

potassium (K): the element with atomic number 19; a silvery-white alkali metal that rapidly oxidizes in air and is highly reactive in water. Potassium is chemically like sodium.

potato: a tuber of the perennial nightshade Solanum tuberosum. The potato plant is indigenous to the Andes mountains.

potential energy: stored energy that may be released; the energy inherent in an object owing to its position relative to other objects, internal stresses, electric charge, and other factors.

power law: a scale-invariant functional relationship between 2 quantities.

pre-adaptation: a trait which is subsequently adaptively employed in another, distinctive way. Pre-adaptations are a fundamental mechanism of evolvability. See exaptation.

precipitation: rain, sleet, ice, snow, and fog; also defined as the quality of being precipitate or hasty.

precocial: animals with relatively mature and mobile young from the moment of birth or hatching. Many, though not all, arthropods, fish, amphibians, and reptiles are precocial. Contrast altricial.

precocious knowledge: inborn knowledge. Precocious knowledge is a telltale of energyism, as it cannot be explained via materiality.

predator: an organism that consumes other animals as a primary food source. A top predator is a predator that is not preyed upon by another organism (pathogens aside). Compare herbivore, omnivore, and saprovore.

predator satiation: an animal species population being so concentrated in an area that some survive despite predation.

preformation: the process of producing primordial germ cells via germ plasm.

preformationism: the disproven hypothesis that organisms develop from miniature versions of themselves – developmental biology as a process of supersizing. Contrast epigenesis.

prehistory: hominin history prior to written records. The term was introduced by Daniel Wilson in 1851, used by Darwin in his 1959 Origin book, and given wider application by John Lubbock in 1865.

presocial: an animal that lacks any of the 3 following traits: 1) reproductive division of labor, 2) cooperative care of the young, or 3) overlapping generations. Contrast eusocial.

primate: a mammal order, containing prosimians (neither monkey nor ape) and simians (monkeys and apes).

primitive (evolutionary biology): evolved early compared to later organisms in a clade.

primordial germ cell: a germ cell that produces a gamete.

prinia: a small insectivorous passerine in the Prinia genus.

prion: a pathogen comprising a misfolded protein that propagates.

proboscis: an elongated appendage from the head of an animal. In invertebrates, the proboscis usually refers to the tubular mouth parts used for feeding. In vertebrates, the term is descriptive of a snout (e.g., shrews, tapirs, elephants).

Proconsul (23–5 MYA): an early hominid.

producer (biology) (aka autotroph): an organism capable of sustaining itself by inorganic means. Plants are producers. Contrast consumer.

prokaryote: an organism that lacks a cell nucleus or other membrane-bound organelles. Archaea and bacteria are prokaryotes. While prokaryotes are single-celled, most can form stable, aggregate communities, such as a biofilm. Compare eukaryote.

propagule: a structure, such as a seed, spore, or cutting, that propagates a plant or other organism.

prosimian: a suborder of primate which includes lemurs, bushbabies, and tarsiers, among others. Compare simian.

Prosperpinus: a genus of sphinx moth with 7 species, including the yellow-banded day sphinx (P. flavofasciata), the Terloo sphinx (P. terlooi), and the Pacific green sphinx (P. lucidus).

protandry: a male that can change into a female.

protein: a single, long, linear polymer chain of amino acids that typically takes a folded structure; a complex organic macromolecule by which living bodies are intelligently built. See enzyme.

Proterozoic (2.5 BYA–542 MYA): the 3rd of 4 geological eons, characterized by early life (based upon an outdated estimate, lasting up to the Cambrian period).

protist: a catchall kingdom of eukaryotic organisms, including algae and amoeba. Most protists are unicellular, though many practice pluricellularity.

protozoan (plural: protozoa): a single-celled, typically microscopic heterotroph. Protozoa live in aqueous environments and soil. They occupy a range of trophic levels. Protozoa are called animal-like protists because they subsist on other organisms.

protogyny: a female that can change into a male.

Protungulatum: an extinct genus of mammals that lived during the Cretaceous and early Paleocene; the progenitor of all placental mammals.

pseudocoelomate: an animal with a body cavity with loosely organized organs, as contrasted to coelomates, with quite organized organs (such as all vertebrates), or acoelomates, like flatworms, who have no body cavity at all.

psychopath: a person without an innate sense of empathy.

psychophysics: the study of the quantitative relations between physical stimuli and perception.

psychopomp: one who guides souls; specifically refers to the ancient Greek belief in conducting souls to the afterworld.

pteridophyte: a vascular plant that reproduces and disperses via spores, producing neither flowers nor seeds.

Pterodactylus: a carnivorous flying pterosaur genus, likely piscivorous.

pterosaur (228–66 MYA): the first flying vertebrates, neither dinosaur nor the ancestor of birds.

punctuated equilibria hypothesis: the hypothesis that speciation occurs in spurts, with long durations of evolutionary stability. Compare turnover pulse.

pupa (plural: pupae or pupas): a development stage in an insect: typically quiescent, often enclosed in a cocoon or case, after the larval stage of development, before emerging as an adult.

purgative: something that works as a cathartic or laxative.

Pyrenean rocket (aka Austrian rocket, Sisymbrium austriacum): a small flowering plant native to the mountains of southern Europe.

pyrrolizidine alkaloid (PA) (aka necine base): a plant-produced alkaloid based upon pyrrolizidine (C7H13N), toxic to many insect herbivores.

python: a nonvenomous snake with 11 extant species, endemic to Africa and Asia.


quahog (aka quahaug, hard clam, round clam, hard-shelled clam): a marine bivalve mollusk.

quark: a subatomic particle that serves as the combinational seed for protons, neutrons, and hadrons.

quartz: a crystal in a framework of silicon-oxygen (SiO4) tetrahedra, where each tetrahedron shares an oxygen atom, effectively rendering SiO2. Quartz is abundant in Earth’s continental crust.

Quaternary (2.588 MYA–now): the 3rd of 3 geological periods in the Cenozoic era, characterized by a series of glaciations and the appearance, and global radiation, of modern humans.

quinone: a class of aromatic organic compounds variously comprising carbon, oxygen, hydrogen, chlorine, and/or nitrogen. Numerous critters produce quinones.


race (sociology): a human population unified by culture; more particularly, of related breeding stock; alternately, a subspecies that may interbreed with other subspecies.

radiation (biology): profuse adaptive speciation.

radiation (physics): a process of traveling electromagnetic waves; also used for a similar sojourn of decaying subatomic particles.

radicle: the embryonic root of a plant, which is the first part of a seedling to emerge during germination and grow into the ground. The plumule is the baby shoot bearing leaves that grows after the radicle.

radiolysis: radioactive molecular decay.

ramet (botany): an individual in a clonal population.

random mutation (evolutionary biology): the absurd notion that evolution proceeds via random genetic mutations.

rangeomorph: a taxon of Ediacaran sessile frondose biota which grew to 2 meters and reproductively spread via propagule.

rare-male effect (aka negative frequency-dependent selection): the process in which the evolutionary fitness of a trait goes up as its relative abundance goes down.

rate-of-living hypothesis: a 1908 hypothesis by Max Rubner that lifespan varies inversely with basal metabolic rate.

ratite: a diverse group of flightless birds.

rattlesnake: a venomous snake with a rattle at the end of its tail. Rattlesnakes kill by bite, rather than constriction. 32 species are known.

ray (zoology): a flat-bodied, cartilaginous, marine fish closely related to sharks.

ray-finned fish (Actinopterygii): a class of bony fishes, comprising nearly 99% of fish species, over 30,000 species; so-called because their fins are webs of skin between bony spines (rays), as contrasted to fleshy, lobed fins (lobe-finned fish).

reactive oxygen species (ROS): chemically reactive molecules containing oxygen.

reception: perception of a communication signal.

receptor (cytology): a cell signal receiver; a specific area on a cell, typically on its surface, with 1 or more proteins which are either receptive to stimulus, or which are identifying something contacting it; the term is also used as a misnomer by virologists for the cell binding site that viruses favor.

recessive (trait): a genetic trait (allele) that is masked by a dominant trait.

reciprocal altruism: tit-for-tat altruism; an organism helping another with the expectation that the favor may be returned in the future.

recombination (genetics): mixing traits during meiosis that introduces diversity in offspring.

rectrix (plural: rectrices): one of the stiff main feathers of a bird’s tail, used to control the direction of flight.

red blood cell (aka erythrocyte): the most common type of vertebrate blood cell, employed to deliver oxygen to the tissues via blood flow through the circulatory system.

red deer: the 4th-largest deer species (behind the moose, wapiti, and sambar deer); resident in Europe and western and central Asia.

Red Queen hypothesis: an evolutionary hypothesis positing organisms’ need for constant adaptation to meet ever-changing environmental demands.

red-tailed hawk (aka chicken hawk (though it rarely preys on chickens), Buteo jamaicensis): a bird of prey endemic to North America.

reef: a rock or other structure underwater.

reflection (physics): a change in direction for an energy wavefront between 2 different media so that the wavefront returns into the medium from which it originated. Contrast refraction.

refraction: energy wavefront deflection by passing from one medium into another, each medium having a distinct velocity. Contrast reflection.

regression (biosphere): sea level lowering. Contrast transgression.

reindeer (aka caribou in North America): a deer of the Arctic and subarctic, resident in tundra and taiga biomes.

religion: a belief system belied by facts. A belief system supported by facts is science. Most scientists are religious: insisting on discredited dogmas, such as “natural selection,” or that the brain generates consciousness and the mind.

renascent: rising again into being or vigor.

reptile: a clade of ectothermic, tetrapod, amniote vertebrates that is neither bird nor mammal. The earliest reptiles evolved over 315 MYA from amphibians that were adapting to aridity.

requiem shark: a shark in the Carcharhinidae family which lives in warm seas, migrates, and practices viviparity.

respiration (cellular): the metabolic processes and reactions that convert nutrients into ATP, with waste products released.

restriction factor: a protein in a cell that interferes with viral replication.

retina: the light-sensitive tissue in an eye.

retinoic acid: a metabolite of vitamin A that mediates the functions of vitamin A required for growth and development. Chordate animals need retinoic acid.

retrotransposon: (aka transposon via RNA intermediates): a genetic element that can amplify itself in a genome. Retrotransposons are considered a subclass of transposons.

retrovirus: a family of single-stranded RNA enveloped viruses that replicate in a host cell via reverse transcription.

reverse transcriptase: an enzyme that transcribes single-stranded RNA into single-stranded DNA.

reverse transcription: the process of creating a single-stranded DNA from an RNA template using reverse transcriptase.

reversion evolution (aka reverse evolution, re-evolution, de-evolution, devolution, backward evolution): evolutionary descent with an unmanifest ancestral trait reactivated (atavism).

rhizobia: soil bacteria of several species that cooperatively provide nitrogen fixation services for legumes. Rhizobia cannot by themselves fix nitrogen.

rhizome: a creeping rootstalk (underground stem shoot(s)) of a cloning plant.

ribosome: the cellular factory for synthesizing proteins from peptide pieces.

ribozyme: an RNA-based enzyme.

rice: the edible seed of plant in the Oryza genus.

rift (geology): a chasm where crust and lithosphere are pulled apart.

river: a natural watercourse, usually freshwater, that flows to a lake, sea, or ocean.

RNA (ribonucleic acid): a macromolecule comprising a long chain of nucleotides. RNA and DNA differ by their sugar: ribose versus deoxyribose (a ribose lacking an oxygen atom). RNA and DNA also differ by 1 nucleobase: RNA uses uracil (U), while DNA has thymine (T).

RNA interference (RNAi): an epigenetic regulator of gene expression. RNAi limits gene expression.

Rodinia (1.1–0.8 BYA): the supercontinent containing all of Earth’s landmass, centered at the equator. Rodinia began breaking up around 800 MYA, bringing an end to the abysmal chill of the Cryogenian.

roe (singular & plural): fish egg masses (clusters).

Roman Empire (Western 27 bce–476, Eastern 330–1453): the autocratic period of ancient Roman civilization following the Roman Republic. See Byzantine Empire.

Roman Kingdom (753–509 bce): the monarchial period of ancient Rome, before the Roman Republic.

Roman Republic (509–27 bce): the period following the Roman Kingdom and preceding the Roman Empire.

room temperature: 17–25 °C; an average of 23 °C.

rostrum: the snout or beak-like projection from the head of a dolphin or other vertebrate. The term rostrum is overloaded with similar meaning for invertebrate parts. The forward extension from the carapace (front section) of a crustacean is its rostrum. Mollusks have beak-like mouthparts which are referred to as a rostrum (or proboscis).

rotifer: a phylum of tiny pseudocoelomate animals, common in freshwater, though there are a few marine rotifers; most are free-living, though ~25 species are colonial.

roundworm (aka nematode): a worm of an estimated 100,000 species in a diverse phylum. Over 28,000 species are known, of which 60% (over 16,000) are parasitic. Unlike earlier-evolved cnidarians (jelly-like marine animals) and flatworms, nematodes have tubular digestive systems, with openings at both ends. Compare flatworm.

rove beetle: a beetle in the most specious family (Staphylinidae), with over 63,000 species in thousands of genera, primarily distinguished by a short shard (wing cover).

royal jelly: a honeybee secretion fed to larvae and adult queens.

ruin lizard (aka Italian wall lizard, Podarcis sicula): a lizard endemic to Europe, most abundant in southern Italy.

runaway hypothesis: a hypothesis that evolution by mating preference can lead to absurd extremes.


Sahelanthropus (7–5.6 MYA): an early hominid, with an admixture of ape and human traits.

salamander: an amphibian typically characterized by a lizard-like appearance, with a short nose, slender body, and long tail. Salamanders have been around for 164 million years.

Salmonella: a motile enterobacteria.

salmon: a common name for several species of fish; others in the family are called trout. Salmon live in the North Atlantic and Pacific Oceans. Salmon are typically anadromous: born in freshwater, migrate to the ocean, then return to freshwater to spawn (reproduce). Some populations of several species restrict themselves to freshwater throughout their lives.

saltation (biology): a sudden evolutionary change from one generation of organism to the next.

sand dollar: a flattened, burrowing sea urchin in the Clypeasteroida order. Less flattened species in the order are called sea biscuits.

sanguivore: a hematophage (blood sucker).

saprovore (aka detrivore, decomposer, saprobe, saprotroph): an organism that consumes decaying organic matter. Compare herbivore, omnivore, and carnivore.

sardine (aka pilchard): a small, oily fish related to herring.

saturated fat: a fat molecule with only single bonds between carbon atoms. Contrast unsaturated fat.

saturniid moth: one of the largest and most spectacular moths. 2,300 species are known.

Saurischia: the order of dinosaurs which includes herrerasaurids and sauropods. Compare Ornithoscelida.

Sauropoda: an order of long-necked, 4-legged saurischian dinosaurs. See Herrerasauridae, Ornithischia, Theropoda.

Sauropsida: a group of amniotes that evolved 320 MYA, from which all extant reptiles and birds descended.

Sauropterygia: a group of successful aquatic reptiles that evolved from terrestrial tetrapods soon after the end-Permian extinction, flourishing during the Mesozoic before becoming extinct at the end of that era.

savanna (aka savannah): a grassland biome with trees sufficiently spaced so that the canopy does not close, despite a tree density that may be greater than a forest.

savanna hypothesis: the unlikely hypothesis that vegetative change provoked bipedality in hominids.

scalar: a quantity representable as a point on a scale.

school (of fish): fish of the same species that swim synchronously. This is most efficient, as the schooling arrangements fish use minimize the drag from wakes created by swimming. Compare shoal.

science: the study of Nature from a strictly empirical standpoint. Compare natural philosophy.

scientific method: a set of techniques for investigating phenomena and acquiring knowledge, ostensibly involving careful observation before guessing what is going on, which is known as forming a theory. Guessing prior to intensive observation is making a hypothesis.

sclera: the white of the eye. Nonhuman primates have dark, barely visible sclera.

sclerophyll: a type of vegetation with hard leaves, short internodes (distance between leaves on a stem), and leaf orientation that is parallel or oblique to direct sunlight. Sclerophyll are typical in chaparral biomes.

screaming cowbird (Molothrus rufoaxillaris): a brood parasite of the baywing, endemic to South America.

scute: an external bony plate or large scale.

sea: a large body of saltwater partly or wholly surrounded by land, not as deep as any ocean.

sea butterfly (Limacina helicina): a zooplanktonic, swimming, predatory sea snail.

sea lily: a crinoid echinoderm with feathery arms on a stalk, attached to the ocean floor.

Sea Peoples: a confederacy of seafaring raiders in the Aegean Sea area. The Sea Peoples sailed the eastern Mediterranean. They invaded Anatolia, Syria, Canaan, Cyprus, and Egypt toward the end of the Bronze Age. The Sea Peoples probably started as a migration of displaced people who turned into an effective military force. They were probably the founders of the Philistine and Phoenician civilizations.

sea slug: a saltwater snail, lacking a shell, or only having an internal shell.

sea snake (aka coral reef snake): a marine elapid, native to warm coastal waters of the Indian Ocean to the Pacific. 69 species in 17 genera are described as sea snakes.

sea squirt: a non-motile, benthic filter feeder. Over 3,000 species are known.

sea star (aka starfish, despite not being a fish) a star-shaped echinoderm. Sea stars have been around for at least 450 million years.

sea turtle (aka marine turtle): a marine turtle of 7 species. The sea turtle species are: the flatback, green, hawksbill, Kemp’s ridley, leatherback, loggerhead, and olive ridley.

sea urchin (aka sea hedgehog): a small, spiny, globular marine echinoderm with tube feet, closely related to the sand dollar.

seagrass: a group of marine flowering plants that resemble

seahorse: a marine fish of 54 species in the genus Hippocampus.

seal: a semiaquatic marine pinniped. Seals are typically barrel shaped, with sleek bodies.

seaweed: a macroscopic, multicellular, benthic marine alga, either green, red, or brown. There are an estimated 12,000 species of seaweed.

sedentism: societal transition from a nomadic lifestyle to living in settlements.

sediment (geology): a soil mixture containing small particles of rock. Sediment is classified by grain size and/or composition.

sedimentary (rock): a rock formed by cumulative material deposit. Compare igneous, metamorphic. See basement.

seed: an embryonic plant covered in a coat, usually with some stored food (endosperm) packed within.

seedhead: an infructescence comprising dry fruit, especially capsules.

selection (evolutionary biology): see natural selection.

self-organized criticality: a property of dynamic systems where a critical threshold exists that, when passed, sets off a substantial reaction.

Selfish Gene, The (1976): a work of unintentional fiction by Richard Dawkins, about genes that act like capitalists.

We are survival machines – robot vehicles blindly programmed to preserve the selfish molecules known as genes. ~ Richard Dawkins

semantics: the study of meaning, especially in linguistics.

senescence: aging.

sensate, sensation: receiving stimuli from sensory organs for collation and interpretation via perception.

sensillum (plural: sensilla): a simple epithelial sense organ comprised of few cells. Sensilla usually take the form of a plate, scale, spine, rod, cone, or peg. Arthropods and squamates have sensilla.

septum (plural: septa) (lung anatomy): a partition for gas exchange in the lung sacs of reptiles and birds. Compare alveolus.

Sericomyrmex: a genus of attine ants.

serosa (serous membrane): the membrane that waterproofs insect embryos inside their eggs.

serotonin: an animal neurotransmitter with various roles, depending upon species. In humans, serotonin is associated with feelings of well-being. Serotonin is also employed by fungi and plants.

sessile: not free to move about. Contrast motile.

Set (aka Seth (from ancient Greek)): the ancient Egyptian god of the desert and storms, which symbolically morphed into the god of darkness and chaos. In Egyptian mythology, Set was a usurper that killed his brother Osiris. Osiris’s son Horus sought revenge on Set.

sex: female or male specialization, excepting organisms which have more than 2 sexes. Colloquially used for the act of sexual reproduction, which combines genetic contributions from a male for a female to produce offspring. Compare gender.

sex-biased gene (aka sex-limited gene): a gene that expresses differently depending upon gender.

sexual dimorphism: an innate size difference between male and female animals. A wide variety of animals possess sexual dimorphism. While males larger than females is typical, every animal group with sexual dimorphism has species with larger females.

sexuality: the state of sexual activity.

shard (aka elytron [plural: elytra]): a hardened forewing in certain insects, particularly beetles and a few true bugs.

shark: an extremely successful order of fish that evolved more than 420 MYA; success owing to a superb generalist design.

sheath (botany): the leaf base when it forms a vertical coating surrounding the stem.

sheep (Ovis aries): a stocky, even-toed ungulate ruminant, domesticated since antiquity for its wool. Female sheep are called ewes, whereas male sheep are called rams.

shield volcano: a large volcano almost entirely comprising fluid lava flows when active.

shiny cowbird (Molothrus bonariensis): a South American brood parasite.

shoal: fish that stay together for social reasons. Compare school.

shore crab (aka green crab, Carcinus maenas): a common littoral crab, native to European and North African coasts. Considered an invasive species for its ready adaptability.

Siberia: the vast Asian portion of Russia (since the 17th century), east of the Ural Mountains.

side chain (often designated as R): a defining component of an amino acid, specific to the amino acid to which it belongs.

sierra: a range of mountains, especially with a serrated or irregular outline.

Sifrhippus (56 MYA): the first equid.

signal: an output of communication.

signal transduction: a 2-step cellular communication process. 1st, an extracellular signaling molecule activates a receptor on a cell surface. 2nd, surface reception prompts creation of another molecule, termed a 2nd messenger, which carries the signal into the cell, typically either the nucleus or cytoplasm.

silica (SiO2) (aka silicon dioxide): a ubiquitous crystalline compound. Silicate minerals make up 90% of Earth’s crust. See quartz.

silica phytolith: a microscopic silica body that forms in a living plant and fossilizes.

sill (geology): a sheet of intrusive igneous rock. A sill is formed when molten lava forces its way into spaces between existing rocks.

Silurian (444–417 MYA): the 3rd period of 6 in the Palaeozoic era, following the Ordovician and preceding the Devonian. The Silurian saw the evolution of jawed and bony fish, and life first appearing on land. The name derives from the Celtic tribe the Silures, in south Wales from where the first studied rocks of the period came.

simian: the suborder of primates comprising the “higher” primates: monkeys, apes, and humans. Simians tend to be larger than prosimians (“lower primates”). See prosimian.

singing: vocally producing melodious sounds.

single-species hypothesis: the disproven but popular notion during the late 1960s that human descent proceeded with only 1 hominin species at a time.

skunk (aka polecat): a small, omnivorous, black-and-white mammal with an odorous spray defense, found in the North America and Southeast Asia. Skunks are typically solitary except during the spring breeding season.

sloth: an arboreal mammal noted for its slow movements and metabolism, native to the tropical rainforests of Central and South America. There are 6 sloth species in 2 families: 2-sloths and 3-toed sloths. All sloths actually have 3 toes: 2-toed sloths have only 2 fingers on each forelimb. The 2 modern families of sloths originated from 2 genera of giant ground sloths. The close similarity of modern sloths is an instance of convergent evolution.

smolt: a fish in freshwater having physiologically adapted to handle saltwater.

smolting: physiological changes that adapt a fish (e.g., salmon) to survive in saltwater (from its freshwater origin).

snake: an elongate, legless, carnivorous reptile descended from lizards. 3,400 snake species are known. See squamate.

snake-necked turtle: an aquatic turtle endemic to the waterways of Australia and southern New Guinea, with the longest neck (relatively) of any turtle group in the world. The neck is so long that it cannot be completely retracted into the shell. Snake-necked turtles are consumers of fish. To stalk prey, they fold their necks against their body, then lunge the head forward as dinner swims by. The turtle opens its mouth and throat to create a vacuum which sucks the prey in, whereupon the mouth snaps shut.

Snowball Earth (~800–630 MYA): a period in Earth’s history of episodic near-global glaciation.

Soay sheep: an early breed of domestic sheep endemic to the island of Soay in Scotland.

social: interacting with others (conspecific or interspecific).

social amoeba: a slime mold with group behaviors.

social intelligence hypothesis (aka Machiavellian intelligence hypothesis): the theory that social demands affect evolution.

sociality (aka sociability): the state of being social; general affinity toward others, especially conspecifics. See gregarious.

sociobiology: zoological study that assumes social behavior patterns are an outcome of evolution.

sociopath: a person with a psychopathic personality whose behavior is antisocial, often criminal. A sociopath lacks a sense of moral responsibility or social conscience.

sodium (Na): the element with the atomic number 11; a soft, silvery-white, highly reactive metal; always found in compounds. Sodium is the 6th-most-abundant element in the Earth’s crust, as silica. As sea salt, sodium and chloride are the most abundant (by weight) dissolved elements in the oceans.

soil: the surface layer of the Earth’s crust. Soil is the product of weathering rock, decomposed organic matter, and the cumulative activities of the biotic community. Soil layers are termed horizons. A cross-section of soil horizons is a soil profile. Soils differ among ecosystems. Soils are classified as young, mature, or old. A young soil accumulates organic matter, hence continues to develop a profile. Mature soil holds its own, and so has a static profile. Old soil loses material as nutrients are leached away. Old soil’s horizon diminishes.

solid: a substance with structural rigidity. Crystals and glasses are solids. Contrast fluid.

soma (somatic cell): a cell forming the body of a multicellular eukaryote. Contrast germline.

somatic hypermutation: a cellular mechanism by which an immune system learns and adapts to new threats.

sophistry: subtly deceptive reasoning or argument.

sound (physics): an audible, mechanical vibration that propagates as a wave of pressure through a medium.

South Equatorial Current: an ocean current that flows east-to-west between the equator and about 20° south latitude in the Pacific, Atlantic, and Indian oceans.

southeastern blueberry bee (Habropoda laboriosa): an efficient pollinator of southern rabbiteye blueberries. The bee is endemic to the southeastern United States. The southeastern blueberry bee is one of few practitioners of buzz pollination.

sparrow hawk (aka sparrowhawk): a bird of prey in the Accipiter genus.

specialist (ecology): a species adapted to its specific habitat. Contrast generalist.

speciation: the process of species formation as a population of similar organisms establish a collective pool of reproductive identity.

species (biology): a distinct population of organisms; more specifically (oriented toward zoology and botany): a population that does not generally interbreed with another population of similar organism. Though there may be no biological impediment, organisms may choose not to interbreed by preference, and hence are considered separate species. Ernst Mayr is generally credited with the modern definition of species.

Species are groups of actually or potentially interbreeding
natural populations, which are reproductively isolated from other such groups. ~ Ernst Mayr in 1942

The definition of species remains controversial. At least 3 dozen plausible definitions have been made from different perspectives (e.g., morphological, genetic, breeding, ecological, behavioral, cladistic).

species diversity (aka species richness): the variety of species in an environment. Compare biodiversity.

speciose: there being many species.

sperm: a male reproductive cell. Compare egg.

spermism: the archaic notion from sexist philosophic men that males provide the essential characteristics of their offspring, while mothers merely contribute material substrate.

spermatophore: a sperm packet used by males of various animal species, transferred to a female’s ovipore during copulation.

spermatophyte: a plant that produces seeds. Gymnosperms and angiosperms are spermatophytes.

sphinx moth (aka hawk moth): a moth in the Sphingidae family (~200 genera, ~1450 species); of moderate to large size, and with rapid, sustained flying ability.

spider: an 8-legged arachnid that injects it prey with venom via fangs. There are an estimated 90,000 spider species, on every continent except Antarctica, adapted to almost all terrestrial biomes.

spiderling (aka hogweed): an angiosperm of over 100 species in the Boerhavia genus, in the 4-o’clock flower family (Nyctaginaceae). Spiderlings, so-called because of the inflorescences on their stems that are suggestive of spider webs, are native to warm tropical regions.

spikelet (botany): an arrangement of a grass flower, with at least 1 floret.

Spinosaurus: a genus of semiaquatic piscivorous theropods native to the rivers of North Africa that lived during the mid- Cretaceous. Spinosaurus is the largest known carnivorous dinosaur.

sponge: a simple, porous, multicellular marine animal, lacking nervous, digestive, and circulatory systems. Sponges rely upon constant water flow for food, oxygen, and waste removal. Most species are marine, though freshwater sponges are known. An estimated 10,000 species are extant.

spore: a desiccated microbe in hibernation, able to remain dormant and survive adverse conditions, such as cold, heat and radiation. Spores are produced via sporulation.

spreading ridge: a mid-ocean ridge with a growing rift along its spine, formed by 2 tectonic plates; an underwater divergent plate boundary.

squamate: a reptile in the Squamata order, comprising all lizards and snakes – scaled reptiles. Squamates are the 2nd-largest (specious) order of extant vertebrates, after perciform (“perch-like”) fish.

squid: a cephalopod of ~300 species, with elongated tubular bodies, short, compact heads, 4 pairs of arms, and 2 tentacles. Squid are strong swimmers.

stadial: an extended cold spell of insufficient duration or intensity to be considered a glacial period.

stamen (aka androecium): the (male) pollen-producing organ in a flower. The stamen has a stalk (filament) and an anther that contains pollen (microsporangia). See stigma.

stasis: static equilibrium.

state (politics): an abiding political institution represented by a government.

status badge: an epigenetic trait which indicates social status.

steel: an alloy of iron (98%) and carbon (2%).

stegosaur (aka Stegosauria, stegosaurian): a group of herbivorous, small-brained, armored (thyreophoran), ornithischian dinosaurs that lived during the Jurassic and early Cretaceous periods.

stem cell: an undifferentiated cell which can differentiate into a specialized cell. Stem cells can divide via mitosis to produce more stem cells. Stem cells are the basis for multicellular organism growth, with differentiation into somatic cells that form tissues with specialized functions. In mature organisms, stem cells serve to maintain and repair tissue in their vicinity. See germline cell.

steppe: an extensive, arid, unforested plain in Eurasia. Compare savanna.

sternum: a compound ventral bone or cartilage of most vertebrates other than fishes which connects the ribs or shoulder girdle or both.

stigma (botany): the (female) portion of a flower that receives pollen during pollination. A pollen grain germinates on the stigma, which is often sticky. The tube-like style connects the stigma to the ovary. See stamen.

stochastic process (aka random process) (probability theory): (the idea of) the evolution of random variables over time.

Stoicism: a Hellenistic philosophy emphasizing self-control as a means for a virtuous life.

stolon (aka runner): a horizontal connection between organisms. Commonly used in botany for an aboveground extension from the base of a cloning plant.

stomata (singular: stoma): plant pores.

Stone Age (roughly 3.4 MYA–3300 bce): the 1st principal period of the 3-age system, noted for use of stone tools, prior to the advent of metalworking. See Bronze Age, Iron Age.

stony coral (aka hard coral): a marine animal in the order Scleractinia that lives on the seabed and secretes a protective exoskeleton of calcium carbonate. Most modern stony coral are colonial.

stot: a gait of quadrupeds involving jumping into the air.

Strait of Gibraltar: the narrow strait the connects the Atlantic Ocean to the Mediterranean Sea.

stratigraphy: a branch of geology related to rock layers (stratification).

strike-slip: an area of tectonic lateral displacement, either between plates or within a continent. A strike-slip at between plates at a boundary is a transform fault.

Struthiomimus: a genus of omnivorous ornithomimid dinosaurs that arose in the Late Cretaceous.

subduction: the process of a tectonic plate moving under another at a convergent tectonic boundary.

subduction plate: a tectonic plate undergoing subduction.

subduction zone: an area where subduction is taking place.

subtractive adaptation: reversion evolution via trait loss.

succulent: a plant with thickened and fleshy tissue for water storage.

sulfonolipid: a sulfur-based lipid.

sulfur (S): the element with atomic number 16; an abundant, multivalent non-metal. Sulfur can react as either a reductant or oxidant. As an organic compound (organosulfur), sulfur is widely employed in biological processes, playing a key role in many enzymes. Sulfur is a component in all proteins.

sulfur trioxide (SO3): a precursor to sulfuric acid; in gaseous form, the primary agent in acid rain.

Sumatra: a large island among the Sunda Islands, in western Indonesia.

Sumer (~5000–1900 bce): an ancient 6civilization of at least 12 city-states, in southern Mesopotamia. Sumer was first settled by a non-Semitic people. The later-arriving Sumerians (~3300 bce), immigrants from Anatolia, referred to themselves as the “black-headed people.”

Sun: the star at the center of the solar system, with a diameter of 1,392,000 km. The Sun’s brightness has increased 30% in the past 4.5 billion years.

Sunda Islands: a group of islands in the Malay Archipelago.

Sunda Shelf: a southeast extension of the continental shelf of southeast Asia into the Gulf of Thailand to the Sunda Islands, notably Sumatra and Borneo.

Sundaland: a submerged continent that was largely exposed during the Last Glacial Maximum.

sundew: a parasitic plant in the Drosera genus, of which there are at least 194 species. Sundews lure, capture, and digest insects via adhesive-tipped glands on stalks grown out of leaf surfaces. The ingested insects compensate for the poor mineral nutrition of the soil in which sundews live.

sunflower (Helianthus annuus): an annual plant native to the Americas. Sunflowers are notable for their large flowering head.

supercontinent: a landmass comprising multiple continental cores. Supercontinents in Earth’s history include: Vaalbara (3.1–2.8 BYA), Kenorland (2.7–2.5 BYA), Nuna (1.9–1.5 BYA), Rodinia (1.1 BYA–750 MYA), and Pangea (300–200 MYA).

superprecocial: animal species with self-reliant young from the moment of birth or hatching. Compare precocial. Contrast altricial.

supremism (religion): the belief that God actively participates in the universe while also remaining distinct from it. Compare pantheism.

supernormality (biology): an exaggerated body feature.

supernova nucleosynthesis: the production of new chemical elements inside supernovae, primarily from explosive oxygen and silicon burning. Iron is the heaviest element produced.

surface hypothesis: an 1883 hypothesis by Max Rubner that the metabolic rate of endotherms is roughly proportional to body surface area.

surface tension: a property of the surface of a substance that allows it to resist an external force. Surface tension in a crystal arises from stretching interatomic bonds, whereas liquid surface tension is more about the extra atoms introduced when spreading out in increased surface area.

survival of the fittest: numerical reproductive success as the ultimate metric of evolutionary fitness; coined by Herbert Spencer after reading Darwin, and subsequently adopted by Darwin.

swallowtail butterfly: a large, often colorful butterfly in the Papilionidae family, of over 550 species.

symbiont: an organism that lives symbiotically with a host.

symbiorg: an obligate symbiotic organism. Eukaryotes with microbiomes are symbiorgs.

symbiogenesis: the evolutionary theory that eukaryotic cells arose via symbiosis between prokaryotes.

symbiosis: 2 dissimilar organisms in continual interaction, often in a mutually beneficial association (mutualism).

symbol: an abstraction that signifies something; a representation of a concept.

sympatric speciation: evolution of a new species while inhabiting the same habitat as the parent species. Compare parapatric speciation, allopatric speciation.

sympatry: a relationship between organism populations which frequently encounter one another in the same geographic area. Compare allopatry, parapatry.

symplast: the inner side of a plant plasma membrane, where water and low-molecular-weight solutes can freely diffuse.

synapsid: a group of mammal-like reptiles, all amniotes (egg layers). Early synapsids are usually called pelycosaurs; more mammal-like ones therapsids.

syncytium (plural: syncytia): a multinucleate cell resulting from multiple cell fusions of uninuclear (single nucleus) cells.

syntax: the patterns of language.

syrinx: the unique vocal organ of birds.

system: an assemblage of interdependent or interacting constituent concepts that form a whole.


taiga (aka boreal forest): a biome characterized by coniferous forest. Taiga is Earth’s largest land biome, comprising 29% of the world’s forest cover.

tamarin: a squirrel-sized arboreal South American monkey.

tardigrade (aka water bear): a 0.2–1.2 mm long aquatic animal.

tarsier: a group of small (10–15 cm) prosimians with enormous eyes, now found on islands in southeast Asia, though it was once more widespread, including Asia, Europe, North America, and possibly Africa. Tarsiers have a different brain structure from other primates, suggesting their early, independent evolution in the line of primates.

taxon (plural: taxa): a classification of organisms. Taxa either have a formal or scientific name. Scientifically termed taxa are governed by nomenclature codes: naming rules overseen by scientific organizations.

taxonomy: the classification of organisms according to their presumed natural relationships.

technology: the products of engineering. Technology includes techniques as well as tools.

tectonic: processes related to the movement and deformation of the Earth’s crust.

tectonic plate: a chunk of the lithosphere capable of movement.

tegu lizard: a largish lizard native to Central and South America, occupying a variety of habitats. Tegus resemble their distant cousins, monitor lizards. The similarities represent convergent evolution. The black-and-white tegu lizard (Salvator merianae) grows to ~1.3 meter and weighs ~2 kilograms.

teleology (evolutionary biology): the obvious and well supported theory that adaptation is goal oriented.

teleology (philosophy): the doctrine that final causes (ends or purposes) exist. Socrates, Plato, and Kant argued in favor of teleology.

teleost: a class of ray-finned fish, with 26,840 extant species in 448 families.

telophase: the cell life cycle phase after anaphase, during cell replication, where 2 daughter nuclei form. The result of telophase is 2 daughter cells. See interphase.

Temnospondyli: amphibians that flourished worldwide during the Carboniferous, Permian, and Triassic periods; a few made it into the Cretaceous.

tensor: a geometric object describing linear relations between other geometric entities (vectors, scalars, tensors). A tensor is a geometric entity entangled with other tensors. See tensor network.

tensor network: a network of tensors.

tergum (plural: terga): the upper or dorsal surface of an arthropod body segment.

termite: a group of colonial eusocial insects, related to cockroaches. Termites are only distantly related to ants. 4,000 species are known.

terpene (C5H8): a pungent hydrocarbon compound produced by various plants, notably conifers, and some insects, including termites and swallowtail butterflies.

Tertiary (66–2.6 MYA): a widely used but formally deprecated geological period which begins with dinosaur extinction and extends to the onset of the Quaternary glaciation.

testicle (aka testis): the male reproductive gland in animals.

testosterone (C19H28O2): a steroid hormone found in reptiles, birds, and mammals; the primary male sex hormone.

Tethys Sea (aka Tethys Ocean): the ocean between the continents of Gondwana and Laurasia during much of the Mesozoic era (252–66 MYA), before the opening of the Indian and Atlantic Oceans during the Cretaceous period. Continental shifts reduced the Tethys Sea, eventuating in the Mediterranean Sea.

tetra: a small freshwater fish in the Characidae family, native to Africa, Central and South America.

Tetrahymena: a genus of freshwater-dwelling protozoa with 7 possible sexes.

tetrachromacy: the ability to see 4 color channels, typically from infrared to ultraviolet. Fish, insects, amphibians, reptiles, and birds are generally tetrachromats. Mammals lost the ability, becoming trichromats (3 colors). Compare monochromacy, dichromacy, trichromacy.

tetrapod: a 4-limbed animal.

tetraterpene (C40H64): a terpene of 8 isoprene units.

theory: fact-based explanation about the relations between concepts. Compare hypothesis.

theory of mind: the cognitive ability to attribute mental states to oneself and others.

Therapsida: the group of synapsids from which mammals descended.

Theria: a subclass of mammals which includes marsupials (metatherians) and placental mammals (eutherians).

thermoacidophile: an organism that prefers a habitat with temperatures of 70–80 °C and a pH of 2–3; a combination of acidophile and thermophile.

thermophile: an organism that can survive a 60 °C or even hotter habitat.

Therocephalia (265–245 MYA): a large-skulled carnivorous synapsid that evolved during the Late Permian and lived through the Triassic.

Theropoda: a lineage of bipedal saurischian dinosaurs that eventuated in birds. Compare Sauropoda.

three-age system: see 3-age system.

threespine stickleback (Gasterosteus aculeatus): a fish native to inland coastal waters north of 30° N which shows great morphological variation throughout its range and is quite tolerant of salinity changes.

Thyreophora: a group of beaked, armored, herbivorous ornithischians that arose in the early Jurassic and lived until the end of the Cretaceous.

tiller (botany): a shoot produced by grass plants after the initial parent shoot grows from a seed.

tin (Sn (from Latin: stannum)): the element with atomic number 50; a silvery metal; first used as an additive combined with copper to produce bronze.

titan triggerfish: a large species of triggerfish, found at reefs and in lagoons throughout the Indo-Pacific, except near Hawaii. Titan triggerfish are busy workers, turning over rocks and stirring sand to scrounge shellfish, urchins, and crustaceans; much to the delight of smaller fish, who feed on the leftovers. Titan triggerfish also munch coral.

toad: a frog with a dry, bumpy, leathery skin. The bumps visually break up a toad’s visible outline, hence helping it to blend into its environment. A toad differs from a frog only by look and its preference for a more terrestrial habitat.

Toarcian (182.7–174.1 MYA): an age in the Early Jurassic.

tolerance adaptation: adaptation toward becoming generalist, capable of surviving in a wider variety of biomes.

Tonian (1,000–720 MYA): the 1st period of the Neoproterozoic era. The supercontinent Rodinia broke up during the Tonian. The earliest fossils (acritarchs) date from the Tonian.

tonne: metric ton.

toolkit gene: a gene which is ancient and highly conserved.

toothed whale: a cetacean with teeth, rather than the filter-feeding baleen of whales; a suborder of cetaceans, including dolphins, beaked whales, and sperm whales.

torpor: a state of sluggishness, with mental and motor inactivity.

trachea (aka windpipe): a cartilaginous tube that connects the pharynx and larynx to the lungs.

tracheophyte: a vascular plant.

trait (biology): an organitypic feature of form and/or function; from an evolutionary perspective, a distinct variant of phenotype, mentotype, or envirotype.

transcendence (religion): the belief that there is a God wholly independent of Nature, beyond the forces of physics. Contrast immanence. Compare supremism.

transcription (genetics): the process of producing an RNA copy from a DNA gene sequence. See translation.

transcription factor: a protein that controls the flow of genetic information during transcription.

transdifferentiation (aka lineage reprogramming): a metaplasia in which a somatic cell transforms into another mature soma without undergoing an intermediate pluripotent state or becoming a progenitor cell type.

transduction (biology): the process of transferring DNA from one bacterium to another via a virus.

transform boundary: a rubbing of tectonic plates at a shared boundary. A transform boundary is a specific type of strike-slip fault. Contrast convergent, divergent.

transgression (biosphere): sea level rise. Contrast regression.

transitive inference: a form of deductive reasoning that allows one to derive a comparative relation between objects based only upon indirect evidence, such as understanding a relation between 2 people based solely upon each of the 2 persons’ interactions with a 3rd person.

translation (genetics): a later stage of gene expression as part of protein biosynthesis, after transcription. Translation transpires in a ribosome.

translocation (botany): the sugary sap distribution process in phloem tissue.

translocation (genetics): a mutation via interchanging genetic material. Compare inversion.

transpiration: normal, controlled release of water by plants.

transposable element: a transposon or retrotransposon.

transposon: a DNA sequence which can change its position within a genome.

traveler’s palm (aka traveler’s tree, Ravenala madagascariensis): a palm-like fruit-bearing angiosperm in the bird-of-paradise genus, native to southern Africa.

tree: a perennial plant with a woody trunk, branches, and leaves.

trehalose (aka tremalose, mycose) (C12H22O11): a disaccharide comprising 2 molecules of glucose.

Trematosauria: one of the 2 major clades of temnospondyl amphibians that survived the Permian–Triassic extinction event, the other being Capitosauria.

Triassic (252–201 MYA): the 1st period of 3 in the Mesozoic era, following the Permian period and preceding the Jurassic. Earth’s land mass was in a single supercontinent, Pangea, during the Triassic. Dinosaurs appeared during the Triassic but did not dominate until the Jurassic. The start and close of the Triassic are marked by major extinction events. The Triassic is named after the 3-layer rocks, found throughout northwestern Europe, that characterize the period.

Triassic–Jurassic extinction event (217–199 MYA): a major extinction event, profoundly affecting life on land and in the oceans, where 20% of all marine families were wiped out. Many large land species were wiped out, including amphibians, and all sizable curotarsans (ancestors to crocodiles).

tribalism: strong in-group loyalty.

tribe: a social group with a shared culture.

trichromacy: having 3 types of color vision receptors. Marsupials and primates are the only known mammalian trichromats, with different receptor types for red, green, and blue wavelengths. Some insects, such as honeybees, are trichromats, but their reception is shorter wavelengths: green, blue, and ultraviolet. Trichromats can distinguish 1 million colors. Compare monochromacy, dichromacy, tetrachromacy.

Trigonopterus: a flightless weevil of over ~200 species native to the Malay Archipelago. Trigonopterus oblongus, endemic to Papua, has a nut-and-screw joint connecting its legs to its hips.

trilobite (526–250 MYA): a Cambrian arthropod; among the most successful of early animals, diversifying to at least 17,000 species and roaming the oceans for over 270 million years.

triploid: having 3 sets of chromosomes within a cell nucleus. Seedless watermelons, tardigrades, and marbled crayfish are triploids. See polyploidy.

trophic: nutritional.

trophic cascade: the dynamic of predator-prey linkages, particularly in affecting carrying capacity.

tropic efficiency: the efficiency of converting food into energy for at a trophic level.

trophic level: a stratum of the food chain.

trophic pyramid: a stratified view of a food chain, from a base of producers to herbivores to predators.

true bug (Heteroptera): a group of insects comprising 40,000 species. Most species have forewings with both membranous and hardened portions. Bedbugs, assassin bugs, stink bugs, and water bugs are exemplary true bugs.

tryptophan (C11H12N2O2): an essential amino acid for many organisms, which typically acts as a precursor for other necessary bioproducts, such as the growth hormone auxin for plants and the neurotransmitter serotonin for animals.

tuatara: a unique gray and greenish-brown lizard-like reptile, but not a lizard, native to New Zealand.

tuber: a plant structure that enlarges to store nutrients.

tundra: a biome where tree growth is hindered by low temperature and short growing seasons. Tundra occurs near the poles and toward the summits of the most majestic mountains.

tunicate: a marine invertebrate chordate.

turgor: the normal state of turgidity and tension in living cells, particularly the distension between the protoplasmic layer and plant cell wall by fluid contents.

turgor pressure: a pressure (turgidity) against cells caused by osmotic flow.

Turing pattern: a pattern that emerges from distributed activity of nonlinear dynamic (reaction-diffusion) systems which exhibits local excitatory and sparse inhibitory connectivity.

turnover pulse hypothesis: a hypothesis suggesting that evolution is nominally conservative, with speciation only when forced by environmental change. Compare punctuated equilibria, opportunistic evolution.

Turritopsis nutricula: an immortal hydrozoan which can reincarnate itself by reverting specialized adult cells to undifferentiated status (transdifferentiation).

turtle: a reptile in the Testudines order, characterized by a unique, defensive, bony shell developed from its ribs. Originating 220 MYA, turtles are one of the oldest reptile groups. See Cryptodira, Pleurodira.

Tutankhamun: Egyptian pharaoh who ruled 1332–1323 bce.

twolobe clarkia (aka two-lobed clarkia; Clarkia biloba): an evening primrose endemic to California.

TYA (aka kiloannum, ka): thousands of years ago.

tyrannosaur: a family of large theropod dinosaurs that lived during the Jurassic and Cretaceous periods.


Uganda: a country in east central Africa, to the north of Lake Victoria.

ultrasonic: a sound frequency above human hearing (20 kHz).

ultraviolet: the 10–400 nm band of the electromagnetic spectrum, shorter than visible light but longer than X-rays.

umami (aka savory): one of the 7 basic human tastes (along with sweet, starch, sour, salty, fat, and bitter), activated by the amino acid glutamate.

ungulate: a group of mammals which use the tips of their toes, typically hoofed, to sustain body weight while moving. Commonly known ungulates include the horse, cattle, bison, camel, goat, pig, sheep, donkey, deer, tapir, antelope, gazelle, giraffe, camel, rhino, and hippo. Even-toed ungulates (Artiodactyla) bear their weight equally between the 3rd and 4th toes, in contrast to odd-toed ungulates (Perissodactyla), which have an odd number of toes on their rear feet, bearing

uniformitarianism: a hypothesis of steady state existence: that the same laws of Nature have always been constant everywhere. Contrast catastrophism.

universe (aka cosmos): a presumed self-contained repository of energy. This universe has some 4 trillion galaxies; half are light (with visible stars), half dark.

unsaturated fat: a molecule of fat with 1 or more double bonds between carbon atoms. A fat molecule with only 1 double bond is monounsaturated. Molecules of fat with more than 1 double bond are polyunsaturated. Contrast saturated fat.

Utahraptor: a genus of theropods native to North America.

utility: fitness for some purpose.


Vaalbara (3.1–2.8 BYA): the earliest known supercontinent.

vacuole: the organelle in cells responsible for autophagy.

vagina: the female sex organ; part of the reproductive tract. The external portion is the vulva. See penis.

vampire bat: a clade of hematophagic bat of 3 genera/species, all native to Central and South America.

vampire finch (aka vampire ground finch, Geospiza septentrionalis): a small, hematophagous finch, endemic to the Galápagos Islands. Vampire finches also feed on eggs: stealing them freshly laid, rolling the eggs onto rocks to break them.

vascular: a life form with vessels to carry fluids; commonly used to identify land plants: vascular plants (aka tracheophytes).

Vedic period (~1500–~500 bce): the Indian historical period between the end of the urban Indus Valley Civilization and a 2nd urbanization which began in the central Indian plain ~600 bce.

vegetative reproduction: any one of several ways that plants asexually propagate without spores or seeds. Herbaceous and woody perennial plants often practice vegetative propagation.

velvet worm: a segmented worm with legs in the Onychophora phylum, of ~180 species.

ventral: the belly or lower side (of an organism). Contrast dorsal.

vernalization: the need for an angiosperm to have a prolonged cold period (winter) before being able to flower.

vertebrate: an animal with a backbone and spinal column. Contrast invertebrate.

vicariance (aka allopatric speciation): speciation when a new geographic barrier arises, separating a population. Compare dispersal.

vinegar fly: a fly that lingers about overripe or rotting fruit, in the genus Drosophila. Confusingly, Drosophila are often called fruit flies. Compare fruit fly.

Viracocha (aka Wiracocha, Apu Qun Tiqsi Wiraqutra, Con-Tici/Kon-Tiki): the creator god in prehistoric South America. Viracocha arose from Lake Titicaca in darkness and brought forth light, creating the cosmos. Viracocha was worshipped as the god of the Sun and storms. He was depicted as wearing the Sun for a crown, with thunderbolts in his hands, and crying tears of rain.

virus: an obligate parasite that infects cells of all types of organisms; a domain of life, alongside archaea and bacteria.

vision: the sense of sight through visible light.

vitalism (biology): the doctrine that there is a vital energy specific to living organisms, distinct from chemical and physical forces; a well-known fact generally rejected by scientists.

vitalism (natural philosophy): the doctrine that living entities are fundamentally different from non-living objects. Contrast animism.

vitamin A: a vitamin needed by the retina of chordate animals for low light and color vision.

viviparity (noun; adjective: viviparous): giving birth to live young. Contrast oviparity.

vocal cord (aka vocal fold): either of 2 folds of a mucous membrane that extends across the interior cavity of the larynx.

vocalization: sound production by an animal through its respiratory system.

volcanism: volcanic activity.

volcano: a rupture in Earth’s surface that affords the flow of hot magma, gases, and ash to escape from below into the atmosphere. Volcanoes are commonly caused by divergent tectonic plates pulling apart.


wabi-sabi: a worldview and aesthetic developed in Japan that centers on acceptance of the transience and imperfection of existence. Wabi-sabi emphasizes simplicity, economy, and a sense of appreciative intimacy with Nature.

wasp: a flying insect of well over 100,000 species, found on every continent except polar regions. Most wasps are parasites or parasitoids as larvae, feeding on nectar only as adults. Many wasps are predatory, feeding their larvae other insects (often paralyzed). Wasp sociality varies from solitary to gregarious.

water: liquid H2O; the elixir of life; an odd molecule like no other.

water cycle (aka hydrological cycle): the cycling of water in the biosphere.

water column: a conceptual vertical column of water, extending from the surface to the bottom sediments.

water flea: a tiny crustacean (0.2–6.0 mm) in the order Cladocera.

water strider: a true bug in the Gerris genus, able to walk on water. Over 1,700 species of gerrids have been identified, 10% of them marine.

wavefront (physics): the locus of a propagating energy wave.

wavelength: the spatial period of a sinusoidal wave; commonly used as a statistical measure of the energy of a waveform, which is mathematically the product of a wave’s frequency and amplitude.

weak linkage (genetics): a variable correlation between genetic code and expression.

weather: characterization of daily or other short-term tropospheric conditions in a locality. Compare climate.

weevil (aka snout beetle): a typically small (>6 mm) beetle of over 60,000 species in several families, mostly in the family of true weevils: Curculionidae. Some other beetles, not closely related, bear the weevil name. Most weevils have long, elbowed antennae that can fold into special grooves on the snout. Many weevils lack wings, whereas others are excellent fliers. Most weevils are herbivores. Whereas larvae typically feed on a species-specific plant (or close relations), adult weevils tend to be less picky eaters. As crop eaters, weevils are generally regarded as pests.

western rosinweed (Calycadenia pauciflora): a daisy endemic to northern California Coast Ranges.

whale: a large marine mammal in the clade Cetacea.

whitefly: a small fly that typically feeds on the undersides of plant leaves.

wild pig (aka wild boar, wild hog, Sus scrofa): the wild ancestor of the domestic pig, found in Europe and Asia, including Japan, and as far south as Indonesia.

wing loading (aerodynamics): total weight of a flyable object divided by the area of its wing.

wood duck (aka Carolina duck): a colorful perching duck endemic to North America.

woodrat (aka packrat): a rat in the Neotoma genus, with the greatest species diversity in the deserts of northern Mexico and the western United States.

wrasse: a clever, carnivorous, marine fish of 500 species in the Labridae family. Wrasse are found throughout the world in tropical and temperate seas.

wren: a small, insectivorous passerine in the Maluridae family, endemic to Australia and New Guinea.


xylem: plant tissue employed to transport water up a plant. Compare phloem.


ya: years ago.

Yamnaya (~3300–~2600 bce): a people of hunter-gatherers and nomadic herders, native to the steppes north of the Caucasus Mountains and Caspian Sea.

yeast: a eukaryotic microorganism classified as a fungus, of which there are 1,500 known species. Yeast are famous for brewing beer and making bread rise. Contrast mold.

Younger Dryas (~12.8–11.7 TYA): the most recent stadial.

Yucatan: a peninsula in southeastern Mexico.


zoology: the study of animals.

zygote: a cell formed by the union of 2 gametes.