The more we look at the behavior of insects, birds, and mammals, including man, the more we see a continuum of complexity rather than any dramatic difference in kind that might separate the intellectual Valhalla of our species from the apparently mindless computations of insects. We see the same biochemical processes, the same use of sign stimuli and programmed learning (even in language acquisition), identical strategies of information processing and storage, the same potential for well-defined cognitive thinking, but very different storage and sorting capacities and, most of all, very different intellectual needs imposed by each species’ niche. ~ American ethologists James & Carol Gould
Every responsive molecule – anything that can take a decisive action – necessarily possesses intelligence. The unified field of Ĉonsciousness populates all animate matter with individualized consciousness, which is energetically embodied in a mind-body. A body may be a macromolecule, virus, cell, organ, or organism. The body includes cohesive energy pathways and centers. A mind is organized in a way appropriate to its body. This is the miracle of life.
Perception is the mental comprehension of sensation from bodily stimuli. Everything animate experiences perception, which necessarily involves abstracting the inputs of sensation and construing some meaning from them. Perception is a constant preoccupation of a mind while in an alert state of consciousness.
Sense of self is essential to survival, both as an individual and as a member of a group. All unicellular organisms possess proprioception: a sense of physical self. So too single cells in a eukaryote.
Recognition requires conceptual comparison to memory. New experiences which cannot be comprehended are remembered, providing the basis for later categorization when similar sensations are perceived.
The mind categorizes by comparing to past experiences, a procedure which requires memory. This basic learning process is universal. Researchers have confirmed learning in slime molds. Worms learn via trial and error like people do, which requires contextual memory of similar situations.
Goal-oriented behavior exists in all life: from viruses on up. Achieving goals requires intelligence, which necessitates the cognition of abstractions that appear as symbolic representations of situations.
In infecting a host, a virus employs mental templates of the chemical signatures that are the target of their goal-directed behavior. Comparison necessarily involves abstraction.
Every thought is necessarily symbolic, with objectified tokens that signify something that naturally evokes emotive qualities: either attraction (desire) or repulsion (fear). These 2 poles define the spectrum of developing goals from which behaviors emerge.
As mentation is of patterns directed at goals, the mechanics of analysis are selfsame, whether of molecular structures or social organization. Flies remember their destination even when distracted. Social wasps and honeybees recognize faces the same way as humans. Sea lions possess the same facility for symbolic logic processing as people. These are but a few known examples from research, which should be considered indicative of a ubiquity of acumen.
Language is symbolic representation codified. The relations between symbols is the basis of syntax.
The mind of every organism is a symbolic processor, capable of situational recognition in light of survival goals. This capability – employing languages for living – is innate in all life.
The root of intelligence is knowledge, which has 2 sources: inborn (precocious) and learned. The ability to learn is grounded in the way the mind works: symbolic processing structured with inclinations, aptitudes, and deficiencies which are innate. Hence, all knowledge has a native foundation. Learning – the accumulation of facts into actionable knowledge – is icing on the cake of intellect: perhaps sweeter in having been hard-won but no less essential than the basic batter of precocious knowledge. Just as tool use is only exemplary of acumen, not indicative of superiority, so too learning is merely a means of knowledge acquisition, no better than just knowing.
On the beach of Fernandina, a Galápagos island, a marine iguana hatches from its egg which had been buried in the sand. Instant death awaits. The newborn lizard must sprint up the beach to the safety of rocks. On the beach in-between are a bevy of racer snakes that know tasty hatchlings are on the menu this time of year.
The iguana instinctively stays still, hoping to elude detection. Once spotted by a snake, or once a path looks possible, the newborn bolts for the rocky ridge. With innate evasive maneuvers, daring, and more than a dash of luck, the hatchling iguana reaches the boulders and begins what it hopes is a less harrowing life.
Some ants can’t build their own nests, so they try to invade another colony. Once mated and ready to lay, a parasitic queen will look for a host nest to sneak into and kill the queen there.
Cheated by Nature in building skills, the parasites have the compensation of innate wiles. Once established, a parasitic queen mimics the scent of the host species to trick the native worker ants into taking care of her eggs. As parasitic ants hatch they too mimic the colony’s scent, hoping to go unnoticed until their numbers can overwhelm the indigenes.
The ruse isn’t foolproof. Savvier host workers aren’t hoodwinked and kill the masquerading outsiders. And the parasites are not only ants with inborn wits. Little host larvae help the cause by eating parasite eggs. The grubs innately know how to tell the bad eggs from siblings to be.
All life forms are more intelligent than they need to be to survive, albeit with deficiencies that make living a challenge.
The fact that they may not understand us while we do not understand them does not mean our ‘intelligences’ are at different levels. They are just of different kinds. When a foreigner tries to communicate with us using an imperfect, broken, version of our language, our impression is that they are not very intelligent. The reality is quite different. ~ Australian biologist Maciej Henneberg
There is no uniqueness, nor superiority, to human intelligence. Quite the contrary. Abstraction absent perception – philosophic concepts – are divorced from actuality. Beliefs based upon such ideas are the source of mental illness, not intelligence. The human world is rife with self-destruction and social dysfunction from faiths and ideologies with do not correspond with how the natural world works – stupidity with grave consequences.
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All organisms have acumen adapted to their habitats. Before surveying animal intelligence, a brief review of other life.
We know so little of the little ones. Viruses, archaea, and bacteria are far too successful to mark it down to dumb luck.
Microbes navigate and adapt. They communicate at the molecular level within themselves and with other species.
Microbes acclimate themselves to other species and accommodate or antagonize with various responses. Through selective genetic exchange, microbes demonstrate what approximates to empathy, and, when times are tough, work for the betterment of their community.
When presented with an abundance of nutrients, single-celled algae bloom into a prolific population. As the food runs out, individuals self-selectively commit suicide to sustain others. The residual nutrients can only be used by relatives and inhibit the growth of non-relatives. Not only does suicide help kin, it can also harm competitors.
Plants are exquisitely tuned to their environment. ~ Canadian botanist Heidi Appel
Plants sense their environment and responsively adjust their activity, morphology, physiology, and phenotype. They account for their resources and plan accordingly.
Though commonly hermaphroditic, many flowering plants recognize and reject their own pollen, thereby averting inbreeding. With intricate molecular comparison behind it, considerable cognition is involved in this process.
Plants solve problems. They meaningfully communicate with their neighbors and other species in the appropriate chemical language. Plants understand and manipulate other species in a vast variety of ways.
Plants’ insights into the biologies and motives of other life forms is unsurpassed. How they acquire this knowledge is inexplicable but must involve analysis of residue molecules from encounters.
Most important, no life is as productive or as beneficent in their creations to other life as plants. Which is to say that the sociality of plants is beyond compare.
While the circumstances of other animals are often much different than our own, we can better appreciate their intelligences than we can plants, fungi, or microbes, as the rhythms of animal lives are comparable to our own.
The circuit of intelligence begins with perception: physical stimuli translated in the mind into meaningful input. Common communication media – touch, sight, sound, and smell – provide much of an animal’s sensations. Other input is produced by habitat phase changes.
A change in air pressure presages a turn of weather. Insects, birds, bats, and even fish sense a shift and change their behaviors in anticipation. Many insects stop producing mating hormones when it feels like rain, as courting prospects are dampened.
A most primal sensation is pain: a discomfort that provokes attention. The earliest-evolved invertebrates – insects, crustaceans, and cephalopods – feel pain and react to it. Mental processing is necessarily involved with every sensation.
Predation can be a matter of move and countermove involving anticipation. In capture or escape, either predator or prey is confounded to the other party’s satisfaction.
Worm charming is practiced by birds, turtles, and humans. It involves vibrating the topsoil by various methods to rouse worms to the surface. Wood turtles and herring gulls stomp their feet.
Moles burrow about in search of prey. This subterranean bustle can bring worms to the surface.
Worms recognize vibrations at a certain frequency range as a predator on the move. In anticipation, they evasively squirm top side.
Honeybees forage over a broad terrain. They then go back to the hive to report environmental conditions and the prospects for fruitful harvesting. This involves maintaining an extensive mental map, then translating specific directions and other salient information into a cogent report that others can understand and appreciate.
The hallmark of social intelligence is culture: the transfer of knowledge among conspecifics, and from one generation to the next. Culture is prevalent throughout the tree of life as an integral aspect of sociality. Horizontal gene transfer among bacteria is a cultural exchange.
Culture is about learning from others. ~ Canadian zoologist Hal Whitehead
Bumblebees socially learn in picking up harvesting techniques by imitating those used by other species. Sometimes they communicate tips among themselves. As they mature and garner knowledge, bees can solve increasingly complex problems.
Bees with experience are able to solve new problems that they encounter, while bees with no experience just give up. ~ Canadian zoologist Hamida Mirwan
Social learning, in which animals learn from others, can enable novel behaviours to spread between individuals, creating group-level behaviours, including traditions and culture. ~ Lucy Aplin et al
People often feel bound to cultural traditions. They are not alone.
Great tits are small, ubiquitous passerines that live in woodlands. They watch other tits forage, learning both locations and techniques to harvesting food. This social learning is often adopted and passed on to offspring, creating cultural traditions. Political conservatives who value tradition for its own sake, these birds hew to social conformity, favoring socially acquired foraging knowledge over personal discovery.
Domesticated animals show physical, behavioral, and cognitive differences from their closest wild relatives. ~ German zoologist Anna Albiach-Serrano et al
Selective breeding of domesticated livestock typically emphasizes growing larger animals. Concomitantly, passive animals are preferred.
Emotive responses are dulled in domestics, especially reduced wariness, and low reactivity to what would otherwise startle. Further, domestication diminishes brain size.
Domestic goats have smaller average brain mass (0.13 kg) than wild goats (0.18 kg), despite having larger body mass (domestic goat: 80 kg; wild goats: 45 kg). That does not mean that domestic ungulates are dumb animals. The cognitive abilities of domestic guinea pigs, swine, sheep, and goats are not lessened, though they are different than their wild cousins, notably in being skewed to their specific environment.
Artificial selection and breeding do not lead to a cognitive decline, but rather to an adaptation to man-made environments. ~ German behavioral zoologist Lars Lewejohann et al
Domestic guinea pigs are better at solving water mazes than those in the wild, but wild guinea pigs are better swimmers.
Pigs, sheep, and goats are surprisingly adept problem solvers. They have excellent long-term memories for how they overcame challenges. And their sociality makes mental demands.
Goats possess several features commonly associated with advanced cognition, such as successful colonization of new environments, and complex fission-fusion societies. ~ English zoologist Elodie Briefer et al
Sheep recognize individual people and respond when their name is called. They mentally map their surroundings and can plan ahead. Their learning ability is similar to simians.
Sheep can perform executive cognitive tasks that have never been shown to exist in any other large animals apart from monkeys. ~ English zoologists Jennifer Morton & Laura Avanzo
As quadruped grazers, intelligence is especially needed to forage and extract food. Social considerations may be important but are secondary. As shown with sheep, ungulates have social skills.
These cognitive abilities contrast with the apparent lack of social learning, suggesting that relatively intelligent species do not always preferentially learn socially. Ungulate cognition is mainly driven by the need to forage efficiently in harsh environments, and feed on plants that are difficult to access and to process, more than by the computational demands of sociality.
~ Elodie Briefer et al
Environmental demands drive cognitive adaptation. From an animal’s perspective, domestication is a change of habitat.
The ability to learn associations between stimuli, actions, and outcomes, and to then adapt ongoing behavior to changes in the environment, is arguably one of the fundamental determinants of survival. ~ Jennifer Morton & Laura Avanzo
The intelligence of our evolutionary cousin, the chimpanzee, closely resembles our own. While we left the jungle to pillage the planet, chimp homesteading acumen surpasses ours in some ways. Chimpanzees more readily recognize the offspring of chimp mothers they have never seen before than people can of human youngsters and their mothers.
A male chimp – Ayuma – was able to recall a random series of 9 single-digit numbers after seeing it for just a fraction of second. In the same test, humans are nowhere near as competent.
Theory of Mind
Theory of mind is the ability to attribute mental states to oneself and others: that desires, intentions, thoughts, and knowledge are mental possessions, and may diverge among different living beings. Theory of mind is self-awareness coupled with the recognition that different self-awareness may exist in others.
The evolution of a theory of mind ultimately derives from its role in facilitating the formation of social bonds. ~ American psychologist Robert Seyfarth & American zoologist Dorothy Cheney
Human infants cannot recognize their own mirrored reflections until they are about 18 months old. Most develop the ability by the age of 2. There are exceptions. Autism delays self-recognition. 30% of autistics never learn it, nor do many of the mentally disturbed.
About the same time babies begin recognizing their own reflection, they start to notice that others have thoughts and feelings of their own. This dawning of sociality is slow to mature. Children only develop a cursory sense of theory of mind at 3 to 4 years of age.
Theory of mind is the cognitive equivalent of empathy and is its prerequisite. Empathy is an imagined projection of another’s emotional state: sympathetically identifying another’s behavior as being in a context that one has emotively experienced. A creature capable of empathy interprets that another being may have emotional states.
Interestingly, human babies exercise empathy long before they conceptually understand it from a theory-of-mind perspective. Neonate response to the sound of another’s cries shows empathy as involving innate knowledge: an inborn conceptualization of distress.
One of the striking characteristics of autism is the absence of empathy. Lack of empathy is shared by psychopaths, who do, paradoxically, often have an intense sense of theory of mind.
Theory of mind is not directly observable. It can only be inferred.
Numerous birds demonstrate theory of mind with their anticipation of future events and how others perceive similar situations. Scrub jay caching is exemplary, as is the foraging strategy of puffbirds, in anticipating the behavior patterns of army ants on the march.
Many more animals can be credited with theory of mind than commonly attributed. For example, for friendship to occur, participants must cognize that the other party has a similar interest in mind. Such understanding of intent is especially striking in interspecies’ friendships.
By tuning in to our feelings, dogs create an emotional channel between our minds and theirs. ~ American novelist and dog trainer Lee Charles Kelley
Dogs do not recognize themselves in a mirror, but they do recognize themselves by their smell. Whether dogs possess theory of mind is controversial only among obtuse zoologists. Devoted dog owners know that their companions understand them, sometimes surprisingly so.
Dogs learn words using associative mapping to physical objects the same way that toddlers do.
Dogs and humans share a similar social environment. They similarly process social information. That might help explain why humans and dogs communicate with each other so readily. ~ Hungarian zoologist Attila Andics
Dogs classify photos of animals the same way people do, which means their cognitive categorization is selfsame.
Like babies, dogs selectively imitate an action based upon how well the imitation works in getting to the desired goal. This suggests cognitive processing like human infants.
Dogs and humans are distantly related. The last common ancestor dates to at least 100 million years ago, and is shared with shrews, hedgehogs, rodents, bats, rabbits, ungulates, and marine mammals, as well as all primates.
When forbidden to take food, dogs are 4 times more likely to disobey in a dark room than a lit one. Which is to say that dogs are inclined to pilfer food when they think nobody can see them. This indicates that dogs can comprehend their owner’s perceptual perspective.
Dogs show a variety of easily identifiable emotional responses. Their faces are emotively expressive and capable of showing mixed emotions. Dogs bond with each other by mimicking emotive facial expressions.
Dogs are exquisite readers of body language. While playing with another dog, a dog can read their motivation and the emotional state of the other dog. Dogs’ rapid mimicry is an involuntary, automatic, and split-second mirroring of other dogs. This phenomenon is present also in humans and in other primates. ~ Elisabetta Palagi
Dogs at a park solicit each other to play together. If the prospective playmate is within sight, a dog gives a visual signal: opening its mouth wide and bowing down. If instead the dog is turned away, or otherwise distracted, the interested dog will give its friend a little nip, to get attention.
Dogs with a stressful upbringing are subject to compulsive behaviors, such as tail chasing. Early childhood stress is known to be a factor in human compulsive behavior.
Dogs are affected by their owners’ personalities and stress levels. ~ American ethologist James Burkett
Dogs have a sense of fairness and feel envy. Being left alone brings anxiety and may lead to depression.
Dogs demonstrate empathy in a variety of ways. Dogs look guilty when scolded by their owner, even if not guilty of doing anything wrong (that is, the owner wrongly accuses the dog). This is an empathic expression, in understanding the emotional context that the owner has.
Dogs vis-à-vis Wolves
Dogs are attentive to the cognitive state of others. So are wolves, who are better at picking up on social cues, even those from humans.
While dogs more readily bond with other species, notably humans, wolves cooperate better with their own kind. Wolves readily imitate other wolves, but dogs do not pay close attention to conspecifics, and so do not learn well from other dogs.
Unlike the natural cooperation of wolves, dogs have strict dominance hierarchies, demanding obedience from subordinates. As wolves became dogs, they were bred for their ability to follow orders and submission to human masters.
The difference in interspecies’ attachment between dogs and wolves owes to their early development. Both dog and wolf pups develop the sense of smell at 2 weeks of age, hearing at 4 weeks, and sight at 6 weeks. But the onset of their worldly exploration differs. Whereas wolves begin at 2 weeks, dogs only start at 4 weeks.
This means that wolves are still deaf and blind when they start exploring. At that tender age, they rely primarily upon their sense of smell.
When a wolf pup starts to hear, new sounds are initially frightening. So too new sights. Those early fears settle into a sense of wariness that a wolf never shakes. Contrastingly, dogs don’t start exploring until they have all their senses working, so they are not wary like wolf pups. Hence dogs more easily form a sense of attachment and feel emotional bonds without the unconscious caution that nags in wolves’ minds.
With a wolf pup, you won’t get the same attachment, or lack of fear. ~ American zoologist Kathryn Lord
Intelligence is a fictitious entity. It has no physical existence. No structure in the brain or elsewhere corresponds to it. No standard definition of intelligence exists, and the concept means different things to different people. There are many kinds of intelligence. Intelligence is closely related to adaptability and survival. ~ American psychologist Roger Thomas
Intelligence is a common catchword for the outcomes of mentation. It is a concept not easily pinned down. Merriam-Webster’s Third Unabridged Dictionary lists the following in its entry on intelligence:
the faculty of understanding : capacity to know or apprehend; comprehension, knowledge; intellect, reason; mental acuteness : sagacity, shrewdness; the act of understanding; ability to perceive one’s environment, to deal with it symbolically, to deal with it effectively, to adjust to it, to work toward a goal; the degree of one’s alertness, awareness, or acuity; ability to use with awareness the mechanism of reasoning whether conceived as a unified intellectual factor or as the aggregate of many intellectual factors or abilities, as intuitive or as analytic, as organismic, biological, physiological, psychological, or social in origin and nature.
Intelligence has many facets, as the above definition points out. Yet, in reading the definition, one is naturally drawn to certain terms that resonate with identification, while others are admitted, albeit with less personal esteem. One’s view of intelligence comes via a built-in bias: by identifying one’s own sense of smarts as a basis for comparing alternate definitions. Those aspects of intelligence possessed are cherished; other facets less valued.
An analytic person values logic over woolly intuition. An intuitive person appreciates insight over tedious reasoning, prone to flaws by assumption. Yet, in their application to behavior, both are equivalent facets of intelligence.
Intelligence has a singular foundation: understanding. Comprehension depends upon the quality of perception. Hence awareness is a critical aspect of intelligence.
Symbolic reasoning and analytic processing – the play of concepts – tend to be highly valued by the intellectually inclined. Such are the academics, psychologists, and philosophers who write on the subject.
Bias begets abstractions as being at the apex of intelligence. The pseudo-rigor of logic seems so much more robust than wisps of intuition. Yet, however understanding is achieved, its quality is selfsame. The quality of intelligence is in its expression.
Appropriate action is either tautological or inscrutable to one who perceives it. However entertaining the exercise may be, trying to evaluate the derivation of intelligence is silly.
Further, to define intelligence as mentation beyond observation renders it an abstraction, and thereby its definition impractical. A credible definition of intelligence must be in its demonstration. In other words, to be assessable, intelligence must be behavioral: in decisions to stimuli, regardless of whether a stimulus is external (e.g., sensing food) or internal (e.g., hunger).
Paradoxically, a preeminent challenge in defining intelligence by its exhibition comes in considering the mentation behind the behavior. One could argue that the definition of intelligence is largely eviscerated by including reflexive behaviors, as no decision is made in their exercise. How could a behavior be intelligent if it is mere reflex?
Many behaviors are biologically programmed; not as rote as reflexes but habitual, where behaviors outside the established pattern are anomalous. Further, learned behavior patterns often become reflexive in their exhibition: what is commonly called skill, and most useful because it is practically a reflex.
Distinguishing between biologically innate and learned behaviors is untenably splitting hairs if intelligence is defined through expression. Besides, many behaviors are a mixture of innate inclination moderated by learning.
Regularity in exercise of a behavior certainly cannot be a criterion for intelligence; nor can variability. Results count. As such, intelligence is appropriate behavior.
This definition of intelligence necessitates a definition of appropriate, which is itself a judgment call. Appropriate is a situational, in both immediate context and longer-term perspective. In this light, intelligence is relativistic, necessitating a frame of reference for its assessment.
Action that serves self-interest in staying alive is the most facile biological sense of intelligence. That withstanding, there is something to be said about the appropriateness of accepting death, as opposed to simply suffering for a bit more time before meeting the grim reaper. The will to live does not necessarily mean a rewarding experience.
Many prey animals surrender once their fate seems sealed rather than struggle against the inevitable. Sometimes, such surrender opens a prospect for escape, as a predator may momentarily loosen its grip. Otherwise, a prey may be more quickly killed, and so its suffering minimized. Given either outcome, one cannot call surrender unintelligent.
Expectation & Purpose
Situational awareness and contingent action are aspects of intelligence, as is anticipation. American psychologist Edward Tolman referred to actions showing expectation as purposive behavior. Tolman sought to show that animals could learn facts that they would subsequently adaptively employ.
Purposive behavior encapsulates anticipation. Expectations that are met reinforce behaviors. Conversely, expectations unmet sound a sour mental note. Rats successfully navigating complex mazes show confusion and disappointment at not being rewarded when that is what they have come to expect. So too our experience in navigating the complex maze of our world.
Herein lies a paradox. While goal-directed behavior is often prima facie intelligent, and expectation as part of goal-directed behavior natural, expectation has a counter-intelligent element, as it presumes certainty for what can ever only be probabilistic. That withstanding, goal orientation simply does not exist without expectation.
If intelligence is measured by success, then its story can only be told in outcomes; which means that one cannot judge the intelligence of a behavior without knowing its result. A seemingly self-defeating behavior may be construed as intelligent if all turns out well, and vice versa.
The context of outcome is tricky, as it involves a temporal perspective. Selfish short-term gains may be short-sighted: stupid disguised as smart. Further, focus on outcome clouds the satisfaction that may come with the effort expended, irrespective of result.
The journey is the reward. ~ American computer marketeer Steve Jobs
Historically, evolutionary biologists have struggled to explain behaviors as intelligent that are not apparently self-serving. To Darwin and his ilk, altruism was the great bugaboo. Enlarging the frame of reference from self-interested survival to kin selection was an obvious step. Further inflation of self-interest to group interest (inclusive fitness) explains behaviors as intelligent that benefit individuals not related to an organism, but which an organism has a relationship with, including behaviors that may be beyond calculation of reciprocity.
Evolutionary biologists have ignored a most important driver of altruism. For the socially inclined, sharing feels good: an intrinsic satisfaction that defies outcome-oriented ‘rationality’.
Rationality should be thought of as maximizing fitness. Typically, we think having many individual options, strategies, and approaches are beneficial; but irrational errors are more likely to arise when individuals make direct comparisons among options. ~ American biologist Stephen Pratt
Expanding the ‘rational’ frame of reference to its fullest, intelligence is demonstrated in behaviors that support life from a long-term perspective; in a word, sustainability. A population that dims the prospects of its future generations to survive can hardly be called intelligent, however cunning or creative its behaviors may appear in the instant. From this perspective, in generating a mass extinction event on a global scale, the much-vaunted intelligence of men is denigrated to sheer stupidity.
All organisms are biologically programmed with desires that promise fleeting satisfaction. The urge for offspring is exemplary: one which conventional evolutionary biologists would spuriously appraise as paramount in the scheme of life’s activities. However natural it may be, breeding (or its attempt) is commonly taxing and can diminish a creature’s quality of life.
While offspring notionally increase life satisfaction for mothers (and fathers) who care for their brood, the picture otherwise is often mixed or negative. Many animals are thwarted in their attempts to breed. Parenting itself is not always psychologically salutary; whence the strong innate urge.
Breeding is exemplary of other desires which can be superfluous to thriving. Better not to want and take what comes. Expectation is a formula for disappointment.
If achievement is the goal of intelligence, acumen appears to be a crap shoot, as causality is often out of one’s control. On this count diligence can trump intellect. If satisfaction is instead the aim, the discarding of desires is the most intelligent thing an organism can do: to do only what is necessary and otherwise simply savor being alive.
Sociality engenders a faculty for shrewdness, as assessing and maintaining relationships is mentally demanding. That withstanding, the tasks of everyday living demand problem-solving and planning regardless of others being involved.
Intelligence shows itself in every facet of living: sophistication in communication; nuances in social behavior; stratagems of predation, and its mirror: predator avoidance and evasion; and physical manipulations of the environment, such as tool use and construction.
All organisms perceive the world and apply cognitive power to deal with it. That power is considerable and confounding if expecting physical brains to correspond to mental prowess.
There is no single locus in the fly brain for memory formation, yet vinegar flies have apt spatial memory for their environment. Besides a mental 3d map, vinegar flies can remember the sizes, shapes, and colors of objects.
When faced with an uncertain situation, vinegar flies deliberate. Decision-making in flies and humans is selfsame.
The brain is neither the source of awareness nor intelligence. This myth is perpetrated by matterists who refuse to recognize the obvious fact that the consciousness-mind-body complex is energetic in its coherence, and so not subject to material inspection beyond the least interesting bits. The science of life is much more mysterious and intriguingly deep than mere meat and matter.
The multi-layered mammalian cortex is not required for complex cognition. Absolute brain weight is not relevant for mental abilities, either. ~ Turkish psychologist Onur Güntürkün
Brain size is nonindicative of intelligence. Instead of contributing cognitive power, big brains may just provide support for bigger bodies which have more to coordinate and more sensory input to process.
Insects make the point. With tiny brains, insects count and categorize objects; judge the direction and speed of moving objects and respond accordingly. Some, such as houseflies, do so instantaneously. That is a lot of mental processing power on display.
A housefly is hard to swat. The tiny hairs on its body sense air currents, allowing instant response based upon recognized wind direction.
Antennae also detect air changes. In flight, by detecting wind gusts, antennae are used to regulate flight speed.
With 4,000 lenses (ommatidia) in each compound eye, a fly has a constant mental representation of practically everything around it. Its visual range is a couple of meters, which is better than average for an insect.
Like other insects, houseflies have dichromatic color vision. While they do not see the low frequency that represents the color red, flies are able to detect polarization.
Polarization sensitivity helps a fly detect slight changes in light quality. An emerging shadow is readily sensed by polarization change.
While a fly does not get a clear picture, it is especially adept at detecting movement; whence the skittishness of flies.
Sensing a threat while in the air, a housefly can flip itself in the opposite direction within a few wing beats by moving its body in an evasive maneuver while adjusting its flight trajectory. Flies can beat their wings over 300 times per second.
Flies do a precise and fast calculation to avoid a specific threat, and they are doing it using a brain that is as small as a grain of salt. They process information so quickly. Flies’ nervous system and muscles are able to control movements to a very, very fine scale. ~ Dutch biomechanist Florian Muijres
Fruit Fly Song
Male fruit flies are using information about their sensory environment in real time to shape their song. ~ American molecular biologist Mala Murthy
A male fruit fly courts a female by chasing her. In pursuit, he sings to her by moderating his wing vibrations.
A male adjusts the pitch and tempo of his mating song specifically to the selected female. The faster and farther away she is moving, the louder he sings. Upon catching up, the serenade is softened to a sensitive ballad.
These fly songs have a lot of variability. He measures his distance to the female and uses information about her speed to determine exactly how to pattern his song. ~ Mala Murthy
Even animals with simple nervous systems, such as damselflies and other insects, may exhibit complex assessment strategies ~ Brazilian entomologist Rhainer Guillermo-Ferreira
Damselflies, the gracile cousin to dragonflies, have been around for at least 250 million years. In that time they have learned how gauge their prospects.
Male damselflies engage in aerial battles to secure the best territory and mates. Before entering these energy-consuming exercises, they take stock of who they are up against. Damselflies consider various strategies and tactics as they take on challengers of different strengths.
To assess an opponent’s vigor, they first take into account wing size and pigmentation, which indicates power. Strong males tend to overcome weaker opponents through tactics that are less energy-taxing but more aggressive: chasing, grabbing, and biting.
Facing an opponent of equal strength, damselflies limit their odds of injury by going head-to-head in aerial display flights that are longer and more intense. This stamina strategy aims at wearing an opponent down through repeated forays.
In mid-fight, contestants regularly pause to assess the situation and decide whether it is worthwhile to press on.
Threat displays of increasing difficulty intensify when the other shows strain. A bested damselfly withdraws, mentally defeated.
It used to be taken for granted that individual recognition was impossible for invertebrate animals. ~ American zoologist Donald Griffin
The 400+ species of mantis shrimp are heavy-hitting predators: marine crustaceans with appendages that serve as clubs or spears (in scientific parlance: smashers and spearers), depending upon species.
To avoid predation, mantis shrimp reside in cavities and burrows in coral reefs. Home is where mating and egg-rearing occur, not to mention a great place from which to stage ambushes.
Prime cavities are worth fighting over, which mantis shrimp do; but mantis shrimp fighting is mostly ritualized gesturing and posturing. Although mantis shrimp could seriously injure each other, they seldom do.
Fighting drains energy. Repetitious battles would be exhausting. Hence the ritualized combat, where the likely victor in a real fight prevails in the mock version.
To top off the adaptation, mantis shrimp can recognize, by chemical cue, other individuals they have encountered. A shrimp avoids the cavity of another that has defeated it, but readily enters the abode of a vanquished foe. Each shrimp earns a reputation.
Trout recruit a moray collaborator more often when the situation requires it, and quickly learn to choose the more effective individual collaborator. ~ English zoologist Alexander Vail
Coral trout are a marine piscivore native to the western Pacific Ocean. The live in the open seas and around coral reefs.
Juveniles are fond of prawns. Adults consume a variety of reef fish, with an especial yen for damselfish.
Coral trout do well chasing prey above a reef or in open water but cannot pursue their quarry if it buries itself in a reef crevice.
If a prize looks like it needs to be pried from its hiding place, a coral trout may enlist a local moray eel to aid the quest. Either the eel takes the prey in the reef or scares it back into the open where the trout can pounce.
Coral trout use gestures and signals to flag the location of a prey to an eel, including head shakes and headstands that point the eel in the right direction.
The eel must of course cooperate in the effort. Some are more willing than others, depending upon how hungry an eel is at the moment. Coral trout are as capable of chimpanzees in choosing the right cohort.
A relatively small brain does not stop some fish species from possessing cognitive abilities that compare to or even surpass those of apes. ~ Alexander Vail
This species is small, less than 2 centimetres across the bell. They’re 96% water. They lack a defined brain or central nervous system. ~ Australian zoologist Robert Courtney
Jellyfish have a gelatinous bell, shaped like an umbrella, trailing tentacles. Jellyfish are the oldest multiple-organ animal, having been in the oceans for 700 million years. There are ~2,000 extant species.
Lacking an identifiable intelligence system, jellyfish have been considered opportunistic grazers. But some are smarter than that.
Irukandji jellyfish do not passively graze. They deliberately fish.
The tiny Irukandji jellyfish is extremely venomous: a single sting of its paralytic toxin can kill a man. Their stingers (cnidocyte clusters) look like a series of evenly spaced bright pearls, running out 1.2 meters. A jellyfish twitches its tentacles as a fishing lure, to attract attention.
They’re targeting and catching fish that are at times as big as they are and are far more complex animals. ~ Robert Courtney
This aggressive mimicry pays off. Larval fish take the bait and are instantly stung. Then they are brought back to the bell and consumed.
It’s a highly successful fishing strategy. ~ Robert Courtney
Irukandji jellyfish fish by day. At night, they contract their tentacles to within 5 cm from their bell, with their cnidocyte clusters bunched up. The jellyfish do this to conserve energy, as their visually oriented prey are less active after dusk.
All animals are subject to cognitive overload: too much information upon which to decide. Factor analysis becomes more difficult when factors pile up.
While easy decisions may be better made by individuals, collective intelligence surpasses the ability of any individual when a larger data set needs to be considered.
There is also the aspect of convergence to statistical normalization with collective intelligence, as outliers are smoothed. Averaging human estimates, such as guessing the number of beans in a jar, tends to converge to the correct answer with more guesses.
Many bird species fly in flocks. Some populations do so for the sheer fun of it: soaring in near unison with friends and family.
There is no leader in a flock. A bird within may decide it is time to turn and neighbors join in. The decision propagates like a wave, at a speed that depends upon how parallel the birds’ paths are.
When difficult decisions need to be made, social insects invoke collective wisdom, and decide together.
Individual insects compare options and make decisions all the time, but some things are hard to figure. Social insects have a significant advantage when making decisions that affect a local population.
Big decisions that affect the colony are left to the colony. For a new nest, honeybees and ants display collective wisdom in picking a site.
A colony can wisely decide between 2 locations even if no single member has been to both sites. The enthusiasm that scouts display for a specific site weighs heavily in the decision. That especially makes sense since all involved have the same criteria in mind.
Rock Ant Real Estate
Whereas humans are subject to housing bubbles, rock ants are rational real estate mavens. They continually monitor their neighborhood to know when new homes are available. Moreover, their search effort is attuned to the quality of the nest they currently inhabit. They put more effort into finding new digs when they are in a poor one, and conversely search less when living luxuriously.
Rock ants teach one another using tandem running: a learner provides interactive feedback to the teacher that it is following. Tandem running is a typical way of telling another rock ant the location of a food source.
Large shoals of fish often move fluidly as a collective. (Whereas a school of fish are of the same species, a shoal of fish stay together for social reasons.) Individuals concentrate on keeping close while maintaining a certain personal space from other fish.
Spacing between fish is important in shoals. If a shoal becomes overcrowded, chaos sets in, as each animal cannot determine a safe direction.
Shoal leadership is efficient, regardless of shoal size. A relative few individuals in a shoal decide where to feed or how to flee. The precise dynamics of this follow-the-leaders swarm intelligence are not fully understood.
The building of structures by animals is ubiquitous. ~ American zoologist Scott Turner
Animals are not the only home builders. Construction has an ancient lineage going back billions of years.
Some bacteria create calcified shells for protection. One seaborne cyanobacterium builds an internal skeleton as a ballast assist.
The bacterium that causes Legionnaires’ disease hides from its host cell immune system by building a vacuole (bubble) in which the bacterium resides. The bacterium jiggers host proteins to divert raw materials for the construction project.
The bacterial proteins use the cellular membrane proteins to build their house, which is like a balloon: it needs to stretch and grow bigger as more bacterial replication occurs. The membrane material helps the vacuole be more rubbery and stretchy, and also camouflages the structure. The bacteria are stealing material from the cell to build their own house and disguising it so that it blends in with the neighborhood. ~ Chinese biologist Zhao-Qing Luo
Protozoa build protective shells (termed tests) by secreting material from their cell surface. For fortification, the marsh-dwelling amoebozoa Difflugia adds swallowed sand to its shell. During budding or fission, material is passed into the daughter, where it is joined by organic cement. The result resembles a tiny croquette.
Plants are the consummate constructors. Once established on land, their lush, verdant municipalities beckoned arthropods, the pioneer land animals.
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Bristle worms are ancient segmented sea worms that have adapted to extreme ecological niches: some living in the coldest ocean abyssal plain, while others tolerate the heat of hydrothermal vents. Bristle worms on the ocean floor burrow.
Crabs dig burrows too. Some fiddler crabs add hoods to their burrow entrance as an adornment to attract females for courting.
Numerous fish species build nests to shelter their eggs, including the large freshwater frankfish, which uses floating vegetation to form a corridor leading to a cul-de-sac end where eggs are laid.
Octopi are often home builders, improving chosen rock crevices that serve as shelter; excavating the cavity by removing sand and stones; bringing stones, shells, molted crab claws, and other ornaments, even bottles, to partly block the entrance.
Small, moth-like caddisflies got their start in the Triassic period, over 200 million years ago. Now there are 12,000 known species.
Adults live but 1 to 2 weeks, having spent weeks, or even months, in a freshwater pupa stage. As larvae, they wrap themselves in cases from selectively cut materials, held together by secreted silk.
Larvae scurry on the sandy bottom of the water body where they live, collecting material. Sometimes a larva will take over an empty case, adapting it as it sees fit. An abode is supplemented as a larva grows.
Caddisfly case construction reflects a larva’s personality. Different larvae have decided preferences for different materials, whether plant stems or tiny pebbles.
Caddisfly larvae have a specific sense of how they like their home to look. If the jagged contour of an outer edge is smoothed away by a pesky human researcher, a larva straightaway acts to rectify the intrusion: collecting fresh material and cutting it just so before gluing it into place to cover the defect.
One caddisfly, Macronema transversum, builds an elaborate chambered case, with well-ventilated flow, and a mesh net to catch food. In its complexity, M. transversum’s creations rival the nests of many birds.
These insect larvae thus exhibit a considerable degree of versatility, not only in the initial construction of their cases, but in repairing them. ~ Donald Griffin
Disparate insects construct a tremendous variety of nests or shelters. Wasps, hornets, bees, and termites are the best known.
Ant colonies are elaborate structures. Ants are also able to improvise in their constructions.
Facing a flood, ants build rafts, using both the buoyancy of the brood and the recovery ability of workers to minimize injury or death. Workers protect the queen by placing her in the center of the raft. Conversely, the youngest colony members, which are considered the most expendable, are put in the most vulnerable positions. The brood are most buoyant, and so they form the base of a raft.
Spiders descended from a scorpion-like ancestor 380 million years ago. By 300 mya spiders were in their modern form, albeit with much evolutionary potential in front of them. All spiders are carnivorous.
Although many spider species have a wide distribution around the world, most live within a specific habitat, having optimized to living in a niche environment.
Today’s spiders are sorted into 3 families. The most basal are the Liphistiidae. Found in Southeast Asia, China, and Japan, these nocturnal, medium-sized spiders live for many years in tube burrows with trapdoors constructed on top.
The Mygalomorphae appeared during the Triassic, over 200 mya. Mygalomorphs are hairy and typically heavily built, with large, robust ‘jaws’ (chelicerae) and fangs. Tarantulas are in this group, as are “trapdoor” spiders, which are distant relatives to liphistids.
Over 90% of today’s spider species are Araneomorphae (aka Labidognatha), which arose toward the end of the Carboniferous, ~300 mya. These “true spiders” have fangs which oppose each other and cross into a pinch. By contrast, tarantulas and their close kin have parallel fangs. Araneomorphs include jumping spiders, cursorial (running) wolf spiders, sheet-weaving dwarf spiders, and the orb-weavers.
Wolf spiders are exemplary of daylight hunters. They visually locate prey and run it down. Many wolf spiders are like cheetahs chasing antelope, with the odd jump thrown in from time to time. Jumping spiders are more ambush oriented, and leaping captures are common.
Wolf and jumping spiders aside, most spiders are short-sighted. Spiders have exquisite tactile senses related to physical vibrations, including sound. Spiders are also pressure, humidity, and temperature sensitive.
Through extensive tactile contacts, spiders create a mental map of their surroundings. Webs rebuilt in the same place require less exploration to establish the best anchor points.
Though tiny, spider brains are big relative to their body size (compared to large-bodied animals). A spider’s central nervous system is made up of 2 incomplex nerve cell clusters (ganglia).
The skillful acumen of spiders, including their ability to learn, is an apt illustration that intelligence is not housed in a physical substrate. While animal minds are linked with brains when they exist, nerve and glia cell activity is coincidental, not causal.
The web functions as an extension of the spider’s exquisitely tuned sensory system. ~ Canadian zoologist Catherine Scott
Spiders have been weaving orb webs for ~200 million years. Not all spiders build webs, nor are webs built just to catch prey.
In the Early Devonian period, when moving from the water to the land, spiders started producing silk to protect their bodies and eggs. The practice gradually turned to hunting: first guide and signal lines, followed by ground and bush webs. Then spectacular aerial webs became popular.
Whereas speciality silks independently evolved, as did novel web designs, the various snares spiders use probably derived from a single original scheme.
All spiders spin silk via glands that produce custom blends of proteins with distinct motifs that impart the perfect properties for intended use. The silks emanate from the abdomen through spinnerets. Most spiders have 6 spinnerets, though some have 2, 4, or 8.
Spider silk is comprised of proteins with blocks of recurring alanine and glycine amino acids. Alanine blocks typically pack together in tiny, dense crystals. These are separated by amorphous regions of glycine. Combinations of the proteins and amino acids are precisely arranged in distinct motifs which gives silk its elasticity and toughness.
Spider silk is a unique material: lightweight and stretchy yet stronger than steel. Its production is a chemical engineering marvel.
The proteins (spidroins) from which silk is spun are stored at extreme solute concentration in a gland in a spider’s abdomen. Spidroins have a helical and unordered structure when stored in silk glands. When converted to silk, that structure changes completely, to one that confers a high degree of mechanical stability while being supple.
When a spider wants to spin silk, spidroins pass through a canal where they are converted to gossamer by lowering pH from 7.6 to 5.7 via enzymatic action within the duct.
Silk fabrication happens with water as a solvent at ambient temperature within fractions of a second. The phase change – from solute to solid fiber – is only possible owing to the nature of spidroin. Spider silk dries via mechanical pulling, not evaporation.
Spidroins are large proteins – up to 3,500 amino acids – that contain mostly repetitive sequences. The most important bits for conversion into silk are at the terminal regions, which are unique to spider silk and are selfsame among different spider silks.
One spidroin end pairs up with other molecules at the beginning of the duct, stabilizing as acidity intensifies. Meanwhile, with increased acidity, the other end unfolds to trigger rapid polymerization of the spidroins.
The result is a fiber that contains regions of crystalline and noncrystalline β-sheets, giving silk its unique properties. A β-sheet is a somewhat uncommon protein structure that forms a twisted, pleated sheet at the molecular level.
Spiders use different gland types to produce different silks. Each silk type serves a different purpose: a slick silk safety line, sticky prey-trapping silk, or fine wrapping silk. Some spiders can make up to 8 different silks.
The qualities of the various silks vary by amino acid content. From a mechanical perspective, spider silk varies in having different soft amorphous and strong crystalline components.
The tensile strength of spider silk exceeds that of steel at equivalent weight, with much greater elasticity. Spider silk conducts heat better than most metals.
Spider silk averages around 3 microns thick. A human hair is 20 times thicker (60 microns).
When twisted, ordinary fibers typically spin back and forth around an equilibrium point, eventually returning to the original orientation. Not spider silk, as such uncontrolled spinning at the end of a dropline could cause real problems for a spider making a descent. Instead, spider silk deforms when twisted, cutting down on back-and-forth spinning.
A permanent torsional deformation in spider dragline silk occurs after even small torsional strain. This behaviour is quite different from other materials. Spider dragline silk displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. ~ Chinese physicist Dabiao Liu et al
The upshot is that spider silk is wondrously designed to allow a spider to steadily descend and dangle on its spun line without untoward spin.
The requirements for spider silk seem almost impossible but are achieved by silk’s amazing microscopic structure. ~ English arachnologist Paul Hillyard
Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information. ~ English zoologist Beth Mortimer
Spider webs are careful constructions, built with acoustic properties in mind. Spider webs sing siren songs. The unique sonic properties of a web attract flying insects, whose curiosity lands them in a sticky situation.
Spider silk transmits vibrations across a wide range of frequencies. From the sound of a plucked strand, a spider can know the type of prey on the web, the quality and intentions of a prospective mate, and even the web’s structural integrity. Spiders receive nanometer vibrations with organs on each of their legs – slit sensillae – which amplify the delicate web information.
Spiders set out to make a web that ‘sounds right’. ~ Beth Mortimer
Whereas a web made of threads with the same diameter better bears force applied at a single point, such as the impact of insects hitting the web, non-uniformity can withstand more widespread pressure, such as from wind, rain, and gravity.
Carefully calibrated amounts of material are employed to capture insects of different sizes. A spider optimizes a web’s strength for its anticipated prey, and to account for environmental conditions.
Spider webs evolved in their sophistication. Earlier web types were more disordered, such as tangle webs, to which sheet webs were a step up. The epitome of spider web construction is in orb webs. Orb webs consist of 3 structural elements: strong framework threads, strong radial threads which converge at the center, and elastic capture threads which spiral around and are beaded with sticky deposits.
Some orb-weaving spiders decorate their webs with additional, conspicuous designs known as stabilimenta. Stabilimenta independently evolved at least 9 times. Though scarcely understood by arachnologists, these decorations are communication devices with various intentions depending upon species.
Spiders create their webs so that portions may be damaged but the web as whole stays intact: sophisticated fault tolerance.
This is a clever strategy when the alternative is having to make an entire, new web. ~ American biomechanist Dennis Carter
The large Australian golden orb weaver incorporates decaying plant and animal matter into its web. This sit-and-wait predator attracts insects using the odor of the debris. The spider replenishes rubbish bits as necessary to keep the scent at its most alluring.
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Tarantulas can produce silk from their feet as well as their spinnerets. Foot silk gives tarantulas better cling to surfaces, which is especially useful for this exceptionally large arachnid.
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Flowers take advantage of electrostatic forces to engender pollination and communicate with pollinators. Through their webs, spiders also enlist rascally electrons to help capture prey.
Insects acquire an electrostatic charge by flying or walking on charged particles. The glue that coats cobwebs electrostatically enlivens threads to grasp at the charged creatures that come close.
Darwin’s Bark Spider
Darwin’s bark spider spins webs across rivers and small lakes in Madagascar. Orbs may span 2.8 square meters. Silk bridges may run 25.5 meters.
Their web construction techniques are unique, as is their silk, which is the toughest natural material known: twice as strong as other spiders’ silk.
Despite spinning large, bark spiders are not looking to nab big prey: only semiaquatic flying insects; but in large numbers. These huge webs may catch 30 bugs at a time.
Darwin’s bark spider weaves the largest web of any single spider. Some spiders collaborate to weave interlaced webs that cover hundreds of meters.
Though web catching saves the bother of hunting, spinning silk and weaving webs take energy too. Webs wear easily. A Darwin’s bark spider typically eats part or all of its web daily and recycles the silk proteins. The webs of bark spiders are extensive enough that the spiders maintain them, but for less than a week, and then they are replaced.
Common House Spider
The common house spider has uncommon cleverness in its web construction. While the spider uses the same glue on its silk, it applies the glue differently, depending upon whether its web is intended to catch flying or crawling insects. The velocity of flying insects requires reinforced attachment.
The common house spider is thoroughly domestic. A male and female often share the same web for extended periods.
Several females may make webs close to each other. But they retain a sense of territoriality and are prone to fight if they encounter one another.
Otherwise, house spiders are not aggressive. They are instead quite skittish: afraid of larger foes and inclined to hide if their web is unusually disturbed.
If spooked, a house spider will flee down a silk escape line. If cornered, as a last resort, a house spider may feign death.
This spider uses its web like a catapult. ~ American zoologist Sarah Han
The triangle-weaver spider constructs a triangular web. It sits near the web’s vertex, holding that section of the web taut like a bowstring until it senses a prey upon the web. The spider then releases the tension, propelling that part of the web, and itself, at high speed toward the prey. The target is entangled in the propelled web. If not hungry at the moment, the spider wraps the capture in a special wrapping silk for later consumption.
The triangle-weaver is not the only spider to manipulate silk strand tension in a web to attack and subdue prey. Many orb spiders do so for prey that otherwise escape quickly. The ray spider pulls its web into a cone, releasing it in a similar manner to the triangle-weaver. Tangle web spiders construct sticky, gumfooted threads that are held under tension and which sometimes lift prey into the web through springy scaffolding silk.
Using a constructed device as a power-amplified weapon offers several advantages over internal mechanisms. The triangle-weaver’s leg-over-leg loading of the web over repeated cycles of muscular contraction lets the spider store enormous elastic energy per unit muscle mass, amplifying physiological limits. Such a system operates analogous to the ion and water pump-driven systems that power the carnivorous traps of bladderworts and stinging nematocyst cells of cnidarians, but at a much larger scale.
The iterative loading allows the spider to precisely regulate web tension and stored energy as needed, enabling the rapid accelerations and range of motion that successfully jerks silk around intended targets.
The system lets a spider interact with prey from afar, reducing the risk of bodily damage from potentially dangerous insects, and triggering the tangling process immediately after prey contact the web.
Spiders avoid getting stuck in their own sticky webs with specific adaptations. Spiders work and walk on webs in a way that minimizes adhesive forces, and their legs are covered in branching hairs that have a non-stick coating.
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Webs are a wondrous way to earn a living, but the lifestyle is limiting. There was a burst of diversification ~100 mya, as ground-dwellers, such as wolf and jumping spiders, abandoned the chore of spinning and maintaining webs to take up more ambitious ways of snagging prey.
Spider senses attuned to their lifestyle. These spiders have keen senses of touch and smell, hear quite well, and can sense atmospheric electrical charges. Wolf spiders have excellent eyesight, whereas many others are nearsighted.
A bolas spider spins silk but it doesn’t weave a web. Instead, it slings a silk strand across a gap, where it waits, dangling a sticky gob from one leg.
Moths are something of a rare treat for web spiders, as moths’ scaly wings let them slip out of spider webs. A bolas snags moths when they are most vulnerable: on the hunt for love. The spider separately releases the female sex pheromones of 2 different moths precisely when they make their nightly flights. A male flies by, catches the scent, and comes in close for a mating session. Instead, the spider swings his lasso and snags dinner. Specializing in multiple moth species with different time schedules is quite a trick.
The water spider lives nearly all of its life underwater, including resting, catching and eating prey, mating, egg laying, and overwintering. Water spiders wait for prey to swim past their air-bubble home, then ‘invite’ them in as a meal. The water spider is endemic to mainland Europe, northern Asia, and the British Isles, residing in ponds and other rather still bodies of water.
This spider is also called the diving bell spider, as it builds a silk-based structure which it stocks with air carried down from the surface to form a livable bubble. The silken support is anchored to a submerged water plant. Young spiders do not build air bells – instead taking over empty snail shells which they fill with water.
Capturing air bubbles on the surface is nontrivial. Using a complex movement, a spider traps a bubble using its hind legs and rear of the abdomen. After the first air load is put into place, a spider spends time extending and strengthening a nascent bell before adding more air. A half-dozen trips are typically needed to stock a home bell with enough air.
Several spiders travel on the breeze. Buoyed by air currents, they soar 4 or more kilometers high in the sky. These arachnids lift a front leg to sense wind speed and electrical potential, letting them know when it’s an apt time to fly. Perched at a suitable high point, they form a silk parachute-glider and balloon away.
At the mercy of the wind, ballooning spiders run the risk of landing on water. They do so with aplomb.
Spiders actively adopt postures that allow them to use the wind direction to control their journey on water. They even drop silk and stop on the water surface when they want. ~ Japanese invertebrate zoologist Morito Hayashi
Antlions and wormlions are wily predators that produce pits of doom. They dig inverted cones in loose soil; then wait, buried at the bottom, for dinner to drop in; typically, ants. Pit shapes vary depending upon soil.
A drop-in meal is seized by the mandibles and poisoned before consumption. Sometimes an ant isn’t grabbed on the 1st attempt. An antlion may then toss sand grains the victim’s way, making the slope a bit more slippery.
The Florida antlion crafts a custom cone, shaped to facilitate falling in and not crawling back out. The steepest chute is lined with fine sand grains.
An antlion is not beyond improvisation. 2 antlions dug pits so close together that an intended insect victim fell into one pit, escaped, then fell into the next. The 1st antlion pursued its prey into its neighbor’s pit.
An antlion larva has no mouth. This keeps grit out.
Antlion larvae get their nutrition in liquid form. An antlion stabs its prey with its mandibles, whereupon it injects venom and digestive juices. It then sucks the resultant ant juice through its mandibles.
An antlion larva has no anus. It can urinate, but solid wastes build up until adulthood, when the gut grows an exit.
A larva’s digestive tract dead-ends partway through its body. Hence, it is imperative to not eat grit, nor try to make a meal of anything indigestible.
Carcasses are flung out of the pit to lie around the rim. This does not discourage business. Quite the contrary. Dead bodies act as advertising. Curious ants come see what happened to comrades. Some fall to the same fate.
Only antlion and wormlion larvae dig pits and have digestive difficulties. With their long lacy wings, adults look like damselflies. By comparison to their younger selves, adults live innocent lives.
Cooperative behaviour and social aggregations are relatively common in many animal groups, but rare in lizards. ~ Australian zoologist Steve McAlpin et al
Many animals build homes for their families. Lizards were long thought an exception, but some are ambitious architects.
The great desert skink of western Australia constructs an elaborate, multiple-tunnel burrow and lives there for many years with his family. Several generations participate in the construction and maintenance of the compound.
Females stay home where the children tend to hang out, sometimes with friends. 60% of their spouses are faithful husbands – a rare fidelity for lizards.
For adults to invest so much in a home within which kids mature, it makes evolutionary sense that these adult individuals are sure that they are providing for their own offspring. ~ Australian zoologist Adam Stow
Constructing a nest is a central experience in a bird’s life. ~ American ornithologist Lester Short
Many birds build nests. The commonly-held assumption has been that nest-building is an innate ability. It is not. While the urge may be inborn, birds must learn to build nests, becoming more skillful with practice.
Birds choose building materials that camouflage their nests. This includes selectively incorporating strategic amounts of contrasting colors, which provides a disruptive effect: breaking up the outline of the nest to help conceal it.
Birds are conscious of hygiene when building. They line their nests with vegetation that deters parasites. Urban birds sometimes use cigarette butts for that purpose.
Despite their efforts at exclusion, birds are never alone in their nests. Their constructions are small ecosystems, providing optimal conditions for a diverse community of tiny critters who use bird nests as a shelter, foraging site, and home to rear their own offspring.
While some unintended nest visitors are trouble, others are downright helpful. Fly larvae act as housecleaners by foraging on feces and uneaten food. The enhanced hygiene from this waste removal benefits chicks.
Bird nests often appear simple. They are nothing of the sort.
A single male bird, interested in attracting a mate, must carefully construct a suitable nest from available materials. This requires fitting pieces to create a remarkably sturdy structure and keep it in good repair with economical effort. Village weavers are exemplary.
The 1st step in making a village weaver nest is being able to tear off a 25–38 cm strip of grass. This is smartly done by perching on a stalk, biting through one edge of the grass blade, then flying with it in the direction of the tip. Doing so takes practice. Young birds tend to tear a strip in the wrong direction or cut strips too short.
The quality of grass matters. Green grass has the right moisture, strength, and pliability. Dry grass won’t do. Appreciating this must be learned.
A yearling village weaver builds a crude nest next to a 2-year-old. Physical maturation and trail and error learning make a difference.
Village weavers become more adept at sophistication in stitches and knots. With practice, weavers build a skill repertoire that affords sturdy construction with efficient material use.
In birds with more elaborate nests, quality varies considerably among individuals. Adept nest builders get better at the craft as they age.
Bowerbirds are medium-sized passerines. There are 20 species, distributed throughout the southeast Pacific, from northern Australian to New Guinea. Bowerbirds reside in a range of biomes, including rainforest, eucalyptus forests, acacia forests, and shrub lands.
A male bowerbird builds a bower to attract a mate, or at least decorates a cleared patch of ground, depending upon species. There are 2 basic bower types: maypole and avenue. Maypole bowers are made by placing sticks around a sapling; some bowerbirds add a roof. Avenue bowers comprise 2 walls of sticks bordering a path.
While nest-building has an innate impetus, as does many behaviors in every species, the craft of building a bower is acquired through extensive learning. Young birds practice for a couple of years, learning from their elders. Bower decoration is a culturally transmitted, and extended by personal aesthetic expression, both in color preference and construction technique.
A bower comprises a collection of aesthetically arranged twigs and sticks, decorated with various objects: pebbles, shells, acorns, bones, bark, berries, beetles, butterflies, flowers, feathers, or even pastel jelly-like fungus. The decorations tend to be colorfully vivid whenever possible, with different objects arranged in certain patterns, color-coordinated in a pastiche.
A bowerbird remembers his bower’s construction. If an arrangement is disturbed, the bowerbird puts items back in their place. Pilfering among males is common, as is recovery, at least by more dominant bowerbirds.
Avenue bowers are designed to be viewed by a female from a certain perspective. A male great bowerbird architects an avenue ending in a court: a stage where the male displays for a potential female mate. The avenue is lined with objects to create an optical illusion that dispels sense of depth; smaller objects up front, larger objects in the distance. This balances the visual display of the bowerbird along with his bower. A female’s attention lingers on a quality display.
Bowers are statements of individual prowess. Mating results demonstrate that the best birds have the best bowers.
Having built a bower of power, male bowerbirds call for females to come view their display. The male positions himself and performs for visiting females.
A male’s courtship dance on his bower stage can be quite intense: various songlike calls, synchronized with prancing and wing flapping, perhaps along with some fine feather fluffing. Many bowerbirds are superb vocal mimics, imitating other local birds and overheard animals. The vocal presentation also includes mimicry of natural sounds, such as waterfalls. A bowerbird production is altogether an impressive creative work of art.
A female looking for a mate may visit multiple bowers, returning to prospects of favor to view the show and inspect the bower several times. Several females end up selecting the same male. Also-rans may go without copulations.
Once a female has established a preferential male, she is likely to return the next year, with less inspection of others’ bowers. Conversely, a female not delighted with last year’s choice shops around.
Females have individual preferences, which may season with age. Young, inexperienced, female satin bowerbirds may find certain male productions too intense, provoking unease. They tend to prefer well-decorated bowers with bountiful blue objects, and their males showing a touch of finesse in their display.
Older females are better in considering holistic package quality: more tolerant of intense display, and less impressed with frill, as contrasted to overall artistic expression and quality bower construction.
Catbirds are monogamous bowerbirds that do not build bowers. Males raise chicks with their mate. All other bowerbirds are polygamous. A female builds her own nest and raises chicks by herself. A male’s bower is simply a statement of artistic achievement.
Beavers are semiaquatic rodents which live in a riparian zone: the interface area between land and a river or stream. Healthy riparian zones are ecologically significant in promoting habitat diversity and soil conservation.
An adult beaver may weigh 25 kilograms or more. The South American capybara is the only larger rodent.
Beavers continue to grow throughout their lives, which may be up to 24 years. Unusual for mammals, which are usually sexually dimorphic, female beavers may be as big, or even bigger, than males of the same age.
Beavers are herbivores, feeding on the bark of favored trees, sedges, pondweed, and water lily tubers. Coyotes, wolves, wolverines, and bears prey on beavers.
Beavers have poor eyesight but keen senses of smell, touch, and hearing. As beavers work at night, bad eyes are no problem.
Beavers are best known for their building proclivities. Beaver colonies build dams on a stream or river to yield a still, deep-water pond that protects against predators and affords floating supplies to facilitate building a lodge in a strategic location.
Beavers also build canals to float hard-to-haul building materials: deepening shallow areas to form channels, so that branches may be floated without dragging on the bottom. Mud is excavated from the bottom and piled up, sometimes forming small islands. Canals are by no means helter-skelter: they run along efficient travel routes.
Dams are built by placing spaced vertical poles which are filled between with horizontally stacked branches. To seal water flow, any gaps between the branches are covered by weeds, mud, and sometimes stones.
Beaver construction techniques are specific. They will precisely whittle sticks to block a drain.
The beaver is a keystone species in its ecosystem: creating wetlands that allow other species to thrive. The standing deadwood that beavers leave behind is beneficial to various plants and animals.
The works of beavers keep the areas where they live ecologically healthy. Only humans shape landscape to a greater extent than the beaver, though to opposite effect. Whereas beavers enhance Nature, men only destroy it.
Beaver dams and lodges are built from the same materials. Lodges lack apparent order or regularity in structure, but a beaver lodge is a comfy home for its inhabitants, with underwater entrances that make it nearly impossible for other animals to enter except muskrats, who sometimes live inside beaver lodges with the resident beavers.
Lodge entrances and the living area are dug out as a final step in lodge construction. A beaver lodge has 2 dens: an entrance den (the mud room), used for cleaning and drying off after getting out of the water, and a family abode. Only a small portion of a lodge is used for a living area.
In late autumn, beavers cover their lodges with mud, which freezes when cold weather arrives. The mud becomes almost as hard at stone, impenetrable to predators. Come spring, beavers leave their embankments, roving around until autumn arrives, where they return to their lodge and begin to lay in a wood stock.
Never one to rush, beavers procrastinate on repairs until the frost sets in, and never set the mud top on until the weather becomes biting cold. In constructing a new lodge, trees are felled in early summer, but building seldom begins before the end of August.
Beavers are thoughtful planners. Adults are adept problem solvers. Their techniques prove the point: from their choice of lodge location (never near shores that won’t accommodate a lodge) to tool use (shaping materials with their teeth to fit perfectly).
Lodge and burrow construction are clear goal-oriented activities, as is reasonable efficiency in bringing the right building materials on site. Beavers vary their dam and lodge building techniques to fit local conditions and available materials.
Beavers are not geniuses with flat tails and a fine coat. Their efficiency in felling trees is at times less than ideal. Beavers sometimes goof: proceeding by trial and error, as if they were merely human in mental ability.
Beavers mate for life, though extra-pair copulations do occur. A widowed beaver will mate again. Both male and female participate in home life: constructing and repairing facilities, rearing offspring.
The 1st month of a kit’s life is spent in the lodge, taken care of by mother, while father maintains the territory. Young beavers spend much of their time playing. They also watch and learn from their parents. Yearlings try to help, though they are often inept.
Beaver skills take time to learn. Older offspring do meaningfully assist: feeding, grooming, and guarding younger siblings.
Beavers may leave home after more than 2 years, but will stay if food resources are short, if there is a drought, or if population density is high. Beavers usually do not settle far from their natal territories.
Beavers are gregarious. They slap the water as an alarm call as well as having more subtle communications. Beavers can recognize individuals by smell, from anal gland secretions.
While kin are tolerated, intruders are dealt with harshly, often violently. So much is invested in developing a territory that defending it is an utmost priority. Beavers get to know their neighbors by scent and are tolerant of them.
A wide variety of animals display considerable ingenuity and versatility in the construction of shelters and structures that serve other purposes, such as capturing prey or attracting mates. These activities require adjustment of behavior to the local situation, to the materials available, and to the changing circumstances at various stages of construction. This necessary versatility often suggests that the animal is thinking about the results of its efforts and anticipating what it can accomplish; acting to attain an intended objective is a more efficient process than blindly following a rigid program. ~ Donald Griffin
The use of tools is an extraordinarily diversified and widespread phenomenon among insects, birds, and mammals. ~ Edward O. Wilson
Employing tools, especially their manufacture to intended uses, demonstrates goal orientation and tactical thinking. The same applies to other strategies that confer gain, irrespective of tool use.
Tools garner a more favorable impression than subtle subterfuges simply because they are artifacts of manipulation. Hard evidence is reassuring to the empirically minded.
Tool use is intelligent when learned patterns of tool use are predicated on the formation and manipulation of internal representations. Many other behaviors, not involving tools, are also predicated on internal representations and are also intelligent. ~ American zoologist Benjamin Beck
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Almost everywhere they live microbes jostle for space and compete for resources. Some bacteria evolved a speargun that they can use to inject a toxic cocktail into rivals, thus eliminating them. The weapon is a sheath containing a sharp-tipped spear. The sheath comprises over 200 connected, cogwheel-like protein rings assembled around the inner rigid spear. When a bacterium fires, the sheath rapidly contracts and pushes the toxic spear out of the cell, which then penetrates a neighboring cell, where it releases deadly toxins.
Pavement ants are fond of honey. If they find a bee’s nest, they’ll drop dirt on the guard bees at the entrance to a hive, knocking them silly or dead; so the raid begins.
Florida harvester ants make pellets by combining sand grains which they dip into honey. The pellets absorb the honey and are then carried back to the nest.
Dolichoderine ants bombard the entrance of the nests of their competitors. A troop will stone emerging ants as they leave the entrance to prevent them from foraging.
As an aid to capture, antlions flick sand grains at prey that fall into their pits.
A female sand wasp builds a nest for her eggs in sandy ground. She digs a vertical shaft in which she will lay her egg. Then the wasp provisions the burrow with a caterpillar she has paralyzed. As a finishing touch, the sand wasp plugs the nest, else the food supply might attract hungry mouths. She covers the hole with sand, but there is the danger of disturbance if the sand is too loose, so the wasp searches for a pebble not quite as large as her head. Holding the stone in her mandibles, she tamps down the sand until it is well-packed; whereupon her maternal task is accomplished.
Other wasp species – in the Ammophila and Sphex genera – pick up a suitable object in their jaws, whether pebble or wood chip, and use it to tamp down a bit of soil to seal and conceal a laid egg.
Funnel ants use bits of leaf or wood to soak up semi-liquid foods, such as fruit pulp, or the body fluids of prey. Funnel ants then carry the sponge back to the colony nest. This lets them transport up to 10 times as much liquid as they could carry otherwise.
Funnel ants tend aphids that live on plant roots, providing much of their sustenance. Subsisting in a subterranean lifestyle, these ants rarely appear on the surface.
Funnel ants were named from their practice of building funnel-shaped openings to their underground abodes. Hapless arthropods drop in for dinner, with themselves as the main course. The antlion pit ploy independently evolved in ants.
There are some 4,000 species of assassin bugs, which characteristically use subterfuge to lure their prey, whereupon they literally suck the life out of them.
One assassin bug lives up to its name with its termite fishing techniques. To disguise its own scent with termite pheromones, an assassin bug picks up bits from near a termite nest and rubs them over its body.
This lets the bug approach a nest opening without setting off a general termite alarm. Having caught a termite and sucked out its tasty innards, an assassin bug will dangle the corpse at the nest opening, baiting other termites to investigate, and thereby become the bugs’ next morsel. One assassin bug with a hearty appetite was seen serially consuming 31 termites with these tricks.
A masked hunter, a type of assassin bug, takes on the guise of a walking dust bunny by picking up and covering itself with various debris, from dust to dead bugs. Bed bugs and flies take the curious bait for a short-lived date.
Assassin bugs that are bee killers collect plant resin on their front legs; then, patiently poised on flowers, use the sticky stuff to grab and hold bees.
Certain assassin bugs in Asia and Australia lure ants with a special sugar-producing structure on their abdomens. The predator places itself on an ant pathway and waits. A victim, drawn to the sweet scent, consumes a bit of the assassin bug’s secretion, which is laced with a tranquilizer that immobilizes the ant. Dinner is served.
Another assassin bug, the Australian thread-legged bug, looks like a small walking stick. It is light enough to walk on a spider web undetected. The thread-legged bug is wily enough to steal spider-captured food from a web when the resident spider is not paying attention. It may even play the silk threads of a spider web like an insect struggling to escape, then attack the resident spider and suck it dry.
Sea urchins drape themselves with shell fragments, algae, pebbles, or other debris for camouflage.
Boxer and hermit crabs use stinging anemones as a shield: prying or picking them up and holding them to ward off attackers or placing them so that an anemone might attach itself onto the crab’s shell to act as a protective device. The crabs are careful in detaching the small anemones from their original substrate, as they are useless as tools if injured.
Hydrozoa are a diverse group of tiny marine animals. Some are solitary, others genetically gregarious. The Portuguese man o’ war is a colonial hydrozoan.
While certain hydrozoa are inveterate drifters, some live sedentary lives: the misnamed fire coral deposits a calcareous skeleton and settles in a coral reef, ignoring its taxonomic differences to true corals by blending in.
Countless species of hydrozoa latch onto something to make a living, whether seagrass blades, animal shells, or just bare rock. Conversely, some hydrozoa are latched onto, and used to fish.
Decorator crabs earned their title by stylishly employing materials to hide from or ward off predators. Some decorators do more than that with selective clientele.
Decorating spider crabs prize a certain hydrozoan which has sticky polyps that can readily capture planktonic prey. The crabs purposely place these hydrozoa on the legs they wave in the current to catch their meals. The hydrozoa are better placed for foraging than they might otherwise be, but they lose a goodly share of the profits to their investors.
Tool use varies greatly among vertebrates. For some, it is as simple as spitting water, which is not actually simple at all.
Archerfish are terrific spitters. On the prowl near the water’s surface, they prey on insects and other small fare on land – grasshoppers, butterflies, spiders – by accurately shooting a tight spout of water from their mouths, stunning the target with their spit.
With luck, the meal-to-be plops into the water for convenient pickup. Otherwise, if the prey is within jumping reach, an archerfish will leap out of the water and grab lunch.
It takes a powerful punch to knock an insect off its leaf. An insect in repose is usually firmly anchored, with a force 10 times its body weight. Yet, in a fraction of a second, an archerfish pops one off its perch.
The impact of an archerfish spit is 3,000 Watts/kilogram; well above the maximum vertebrate muscle power of 500 W/kg.
Amplification of muscle power occurs outside the archerfish: by creating a hydrodynamic instability in its spit stream, akin to that used for inkjet printing. The archerfish modulates the velocity of the jet coming out its mouth to achieve a gradual increase of mass and velocity accumulated at the head of the jet. The technique forms a single, large, water drop that abruptly smacks the prey with a powerful punch.
Archerfish load up according to the size of the prey: using more water for larger, heavier targets. An archerfish may squirt a single shot or spray a fusillade.
An archerfish must accurately gauge its prey’s distance for the jet to coalesce into maximum impact. Knowledgeable archers may aim just below their prey, to knock it straight down into the water instead of whisking it away in a straight-on shot.
Experienced spitters have close to a 100% hit rate. By stark contrast, young archerfish don’t have the knack.
Spitting skill is not innate. Accuracy takes practice. Fry hunt in small schools, improving the odds of shooting a meal; though inexperienced individuals cannot successfully hit a target if it is moving even a centimeter a second.
Target-shooting lessons can come at someone else’s expense. Archerfish live in groups and have fantastic observational learning ability.
Inexperienced archerfish extensively watch others to learn technique. After watching 1,000 attempts, regardless of success, novices have learned enough to make successful shots at rapidly moving targets.
Observational learning ability is termed perspective-taking. An archerfish can mentally assume the viewpoint of the fish it is watching to fully appreciate the experience.
Archerfish pick out their stationary targets using the same mental search strategies that humans employ in trying to discern objects in a cluttered background. For moving targets, they adjust the trajectory of their jets based upon the speed that the target is moving: aiming farther ahead if the prey is flying faster.
Archerfish compensate for the optical distortion produced by the water-to-air transition. This requires learning the physics involved with distance, relative position, and target size.
If a target is flying low, archerfish use the sophisticated stratagem of turn-and-shoot. The fish fires while simultaneously rotating its body horizontally to match the lateral movement of the target. Thus, the ejected jet of water tracks the target on its airborne path.
Archerfish are adept entomologists: visually identifying insects to know whether they are tasty (and stingless), and nutritious enough to go to the bother. If dinner is not in the air, archerfish readily forage like any other fish lacking the skill to spit.
Archerfish also use their spitting ability underwater to stun prey hiding in sediment. The fish alter the blast to suit the type of sediment.
Archerfish use the same dynamic mechanism to produce aerial and underwater jets. They employ the same basic technique to adjust their jets in both conditions. ~ German animal physiologist Jana Dewenter et al
How archerfish are able assess sediment characteristics before taking a shot is not known. Doubtlessly it is an acquired skill.
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Archerfish are not the only fish interested in tasty tidbits that fall in. Halfbeaks will happily steal the fruits of archerfish labors.
This rivalry prompted adaptations. Archerfish evolved to predict the trajectory of a falling prey, launching themselves where it will it hit the water while still coming down. This allows archerfish to beat halfbeaks by an average of 163 milliseconds: a close race. That is during the day. At night, halfbeaks have the advantage. Archerfish rely upon their vision to get a jump start.
Halfbeaks have 5 times as many sensory cells on their backs as archerfish. This gives halfbeaks greater accuracy in detecting the waves of prey which have hit the drink.
Archerfish win when they can use vision, but halfbeaks win in the dark. ~ German marine biologist Stefan Schuster
An orange-dotted tuskfish off Palau digs a clam out of the sand, carries it to a rock, and repeatedly slams the clam against the rock until the shell is crushed enough for the fish to get at the clam. Tuskfish are in the wrasse family, one of the largest and most diverse families of marine fishes.
Wrasses are typically inquisitive. All are carnivorous, with sharp eyes and a sensitive sense of smell. Various wrasse have been observed using tools.
Some fish – including the South American cichlid and the brown hoplo – lay their eggs on leaves, which they move to a more protected area if the present home ground appears threatened.
Amphibians and reptiles are not big tool users. Horned frogs bury themselves in the ground as a hunting technique. If they aren’t completely covered, they’ll pitch lumps of dirt on their backs using their feet.
Crocodiles lure birds using fish bait. After eating much of a fish, chunks will be left floating on the water’s surface. A crocodile will submerge itself underwater, with only its eyes sticking out, awaiting a scavenger to fly down and help itself to the scraps. Similarly, to lure avian nest builders, crocodiles put suitable sticks on their snouts.
Herons, gulls, and kingfishers break food up to serve as fishing bait. Great herons drop leaves or small sticks into moving streams and then run downstream to snatch any small fish that their lure has attracted. Burrowing owls place dung out as bait for dung beetles, then wait motionless for their arrival.
An African black egret uses its body as a tool: forming a tent-like canopy with its wings to create a shaded area from the blazing African Sun, drawing unsuspecting fish looking for a place to shelter. Black egrets do not make wing tents in the early morning or when it is cloudy. Instead, they merely stroll along to find fish.
Egyptian vultures drop stones on ostrich eggs to break the tough shell. On the wing Australian black-breasted buzzards drop rocks on emu eggs to crack them.
There have been many reports of other birds dropping objects to desired effect, including a male osprey bombing an intruder osprey with rocks, and a sulfur-crested cockatoo dropping twigs onto a pair of bat hawks sitting on a lower branch of a tree.
A song thrush at its anvil – hammering a snail-shell against a rock – is a familiar sight in European gardens. The thrush knows just how to crack away to loosen a snail’s grip on its shell. Naked snails are slimy, so a thrush wipes the snail off on the ground, to remove as much mucus as possible, before swallowing it.
Black kites are called fire hawks by indigenous Australians. The kites pick up smoldering sticks from a brush fire, drop the twigs on unburned grass, then swoop to feed on the small animals fleeing the fresh fire.
Bald eagles are known to thrown stones, as are black-breasted buzzards. Bristle-thighed curlews have been seen flinging coral pieces to break eggs.
White-winged choughs drop or throw previously consumed mussel shells to break fresh mussels. Choughs also use shells to pound on the next mussel meal.
Wild Australian brush turkeys accurately kick dirt and debris to thwart attack – such as against a lace monitor lizard.
Woodpecker finches use twigs or cactus spines to pry insects out of crevices and cavities in trees, as do pygmy nuthatches and mountain chickadees. Using these picks lets them reach otherwise inaccessible prey, largely hidden from view.
Woodpecker finches, endemic throughout the Galápagos Islands, have no choice but to resort to tools: their tongue is too short to be of much use. At least half of this finch’s food is had through tool use, making woodpecker finches the most proficient tool users besides humans.
Woodpecker finches forage using different stratagems, depending upon the season and habitat. Insects in cracks and crevices are impaled or preyed out with a sharp stick or cactus spine.
Wood-boring grubs must first be accessed. A woodpecker finch begins by pecking a hole in the branch until it reaches the grubs’ den. The finch then flies off to select a suitable tool for excavation. Probing the tool deep into the hole either drives the prey out or is used as a lever to prize a grub to the surface.
Failing to find the perfect implement is no impediment to a woodpecker finch. If no suitable twig or spine is readily available, a bird selects a larger item and whittles it down to size, removing any side-projections in the process.
An African grey flycatcher was seen fishing for a winged termite with a grass blade by sticking it into a hole. The flycatcher pulled the blade out when a termite had grabbed it with its mandible.
Hyacinth macaws use wood slivers or leaves to wedge nuts open. Caged yellow-crowned parakeets use twigs to rake in seed that could not otherwise be reached.
Great herons drop one of their own feathers on to the water as fish bait. Unsuspecting prey respond to this novel object by closer inspection, nibbling to check for food potential; whereupon the heron stabs the fish and eats it.
A white stork mother gives her chicks a drink by squeezing damp moss with her beak. A male gila woodpecker dips a bit of bark into honey to soak it up, then takes the honeyed bark back to waiting nestlings. Brewer’s blackbirds soak grasshoppers in water to soften them up before taking them back to their fledglings at the nest. Over 30 species of birds have been observed dipping or soaking their food in water before swallowing it.
Dozens of different birds have been seen using tools. Finches, parrots, and corvids are notable for making tools, typically by pulling suitable twigs from trees. Individuals in practically all of the 120 species of corvids may cagily fashion and use a tool if the need arises and materials are available.
They are in a special situation with unpredictable resources. ~ Austrian ornithologist Alice Auesperg
The Tanimbar corella is a small white cockatoo endemic to the islands of the Tanimbar archipelago in Indonesia. Like most corellas, they live in social groups of 10–100, roost in tree holes, and mostly eat seeds and nuts.
The Tanimbar corella can solve problems involving sequential steps. This corella is also able to solve complex mechanical problems.
Besides learning from others, and by trial and error, corellas spontaneously innovate to make tools to accomplish desired tasks. They are quick to adapt their behavior when a situation changes.
Male Tanimbar corellas are better problem solvers than females. They need to be, as they must supply females with what they need at the nest.
Both sexes exhibit self-control for anticipated gain. An experiment showed that they would resist eating one nut (a pecan) given to them to trade up to a more desirable nut (a cashew).
The Tanimbar corella is a demanding pet. Being as smart as it is, this bird easily gets bored.
He must have been trained for this. As soon as the police got close, he started shouting. ~ Brazilian policeman
Brazilian vice cops took into custody a parrot who had alerted its owner of a drug raid by shouting: “Mum, the police!” Once arrested, the parrot refused to speak – determined not to be a stool pigeon.
For all its apparent cleverness, tool manufacture and use are not necessarily a sign of a smarter bird. Tool-using woodpecker finches are no more adept at tasks than other individuals in the same population that don’t bother with tools. The closely related small tree finch, which never picks up a tool, does just as well.
So, a tool is just a tool, and an unreliable indication of comparative intelligence. Tool use in captive birds and mammals is more prevalent than in wild counterparts because prison can drive anyone stir crazy.
With exceptions, mammals are not big tool users; no more than certain insects, such as ants. The most prominent exceptions are marine mammals, rodents, elephants, and some primates who often avidly use tools.
For primates, tool use is opportunistic. Upon finding a food resource better accessed using a tool, if the materials to make a tool are available, a monkey or ape can rather ingeniously figure out how to construct and use a tool to get at the food. If tool materials are not available, so it goes; but not always. A chimp may travel a kilometer to obtain the right material to use as a tool. Tasty treats are worth the trouble.
Numerous carnivores enlist the use of hard objects to help them break into protected food. Monkeys often crack open crabs and nuts with stones: either bashing the food against a rock, or vice versa. Sea otters do the same with the bivalves they eat.
Ever-nutritious eggs are especially prized. The trick is getting them open. Skunks and mongooses have special body movements that let them fling bird eggs against rocks with aplomb. Lions, though attracted to ostrich eggs, have no special method of opening them, and therefore often find such eggs a source of frustration rather than sustenance.
Even in mammal species inclined to tools, use is often cultural: limited to certain individuals or groups. In contrast, insects that use tools consistently do so.
Wolverines live in cold mountainous forests. They are opportunistic foragers that survive the harsh winters by caching food in preparation for the lean months. To prevent microbial and insect scavengers from eating their caches, wolverines smartly tuck their supplies into crevices that provide refrigeration. Caching cool is a tool.
All animals are anatomically constrained in the number of discrete call types they can produce. By combining calls into meaningful sequences, animals can increase the information content of their vocal repertoire despite these constraints. Additionally, signalers can use vocal signatures or cues correlated to other individual traits or contexts to increase the information encoded in their vocalizations. ~ Swiss zoologist David Jansen
Communication necessarily involves abstraction. Every syllable, however signaled, is a metaphor for a concept.
Complex animal vocalizations comprise syllables which are arranged into patterns that present a message. Even the same single syllable can do so via variation in presentation.
The adults of many mongoose species live largely solitary lives. By contrast, the banded mongoose is colonial and gregarious.
Banded mongooses cohabit in mixed-sex groups of 7–40 individuals (averaging ~20). Besides foraging as a unit, they sleep together at night in underground dens, which are often abandoned termite mounds.
A group changes its den every few days. If no refuge is available, they lie on each other in a compact layered arrangement, with heads facing outwards and upwards to make the most of sentry while snoozing.
There is no strict hierarchy within a banded mongoose group, but attempted infanticide will ensue if a subordinate female gives birth, but older, dominant females in a colony do not. Banded mongooses evolved the ability for females to synchronize birth, so that a colony litter is not subject to such self-destruction. A communal litter peaceably lives if there is a chance that one of the offspring belongs to a dominant female.
Otherwise, banded mongooses are seldom aggressive within a colony. Squabbles about food occasionally arise, but the first to put dibs on it gets it.
Conversely, an encounter between groups becomes a brawl, sometimes with injuries, and even deaths. Banded mongooses war over food, territory, and sexually receptive females.
20 or 30 mongooses on each side arrange in battle lines. They all rush forward and fighting breaks out. These fights are very chaotic. ~ English zoologist Faye Thompson
Despite the ferocity, females in heat will often mate with males from a rival group during a dustup. Banded mongooses rarely leave their natal group, so group members are closely related. Battles between groups are an opportunity for outbreeding.
Biological parents do little parenting. Younglings are cared for by sundry colony members.
Pups often pick out an adult to be their mentor through infancy. It may be a sibling, cousin, or uncle. The pair spend most of their time together, with the mentor looking after the youngling until it can fend for itself, albeit provoked with frequent begging by the little one.
Banded mongooses have culture: passing on traditions, notably the best foraging spots and other tips, such as how to access the meat in prey with hard shells. To learn, a pup imitates its mentor.
Besides territorial scent markings, which also serve as status updates, banded mongooses make monosyllabic calls that last 50–150 milliseconds. Despite their brevity, these calls identify the animal calling and what it is doing.
Frogs and bats structure single syllables in meaningful communiqués. There are likely many other such species that have simple but content-rich messages. It’s just that we have not paid much attention to the communication skills of other animals.
The highest form of pure thought is in mathematics. ~ Plato
An essential skill for survival is applied mathematics. Time, space, and numbers allow animals to forage, find their way home, and migrate daunting distances. Knowing the number of immediate predators, or the size of a neighboring group, can lead to life-or-death judgments.
Many species are sensitive to quantity. Spiders know how many prey they have tucked away on their webs.
Numerous cues keep ants on the navigational straight and narrow, including counting their steps, sensing the polarization of sunlight, as well as keeping track of visual, olfactory, magnetic, and vibrational landmarks. An ant’s mental map of terrain is at least as intricate as any other animal. It has to be, as an ant’s life is forfeit if it loses its way.
Honeybees can tell quantitative differences. They can rank quantities according to the rules “greater than” and “less than.” Honeybees also understand the concept of nothing. Children do not grasp the symbolic number zero until they are 4 years old.
“Nothing” can be informative. ~ German zoologist Andreas Nieder
Several ancient human civilizations lacked the full understanding and importance of zero, leading to constraints in their numeric systems. ~ Australian zoologist Scarlett Howard et al
Newborn chicks understand both relative and absolute quantities. Their mental number line – running left-to-right small-to-large – is identical to innate human conception. Chicks also have a good sense of ratios.
Monkeys and birds can not only distinguish numerical quantities but also grasp the empty set as the smallest quantity on the mental number line. ~ Andreas Nieder
It’s all about context. ~ American ethologist Ted Stankowich
Cars on the highway traveling at unnatural speeds kill a lot of birds. Those birds that do manage to live learn the rules of the road.
From observation, birds figure the average speed of vehicles on a section of roadway and adjust their flight patterns to accommodate traffic. Speeders are an especial danger, as birds do not expect breakneck drivers.
Animals prefer habitats that contain a higher percentage of preferred food items and avoid habitats containing a higher proportion of predators. ~ Canadian psychologist William Roberts
Foraging for nectar may not seem too complex, but it is a craft to perform it efficiently. The traveling salesman problem (TSP) – efficient multiple-stop route formulation – has vexed human problem solvers since first considered in 1832. TSP is a computationally difficult (NP-hard) problem to solve. But bumblebees manage it.
Bumblebees optimize their nectar collection. Individual flowers vary in nectar content, especially considering those already recently harvested. A bumblebee remembers visited flowers and selects the most easily accessible flowers that have the highest probability of rich reward. Bumblebees solve TSP using spatial memory and a bit of trial and error learning.
Sea Star Geometry
Sea star larvae swim about for 2 months before settling down. They propel themselves by controlling thousands of beating, hair-like cilia on the edges of their bodies.
By selectively coordinating some cilia to beat opposite the direction they are swimming in, larvae dynamically create vortices in the water. These whirlpools pull algae and other foodstuffs from far away into a sea stars’ path. Sea stars optimize the number and effect of the vortices to maximize currents toward them. Sea star larvae are experts in the applied 3d geometrics of fluid dynamics.
Whipping up whirlpools slows a sea star down, but even a little larva knows the importance of a good meal. With full bellies, young sea stars give the whirlpool making a rest and get along.
Math skills are analogous to social skills. One would not be effective socially without a decent sense of numbers. Gregarious animals need to discriminate numerically and gauge probabilities, at least intuitively, to successfully cope within a group, and especially to lead a tribe.
Lionesses live their lives in prides of female relatives. They share cub-rearing. Lionesses recognize each other’s roars. When hearing the roars of unfamiliar lions, they count how many there are.
Even though spotted hyenas live in clans of up to 90 individuals, they spend most of their day in smaller, more vulnerable groups. Like lions, hyenas count unfamiliars and assess odds.
Spotted hyenas are more cautious when they’re outnumbered and take more risks when they have the numerical advantage. ~ American zoologist Sarah Benson-Amram
Children as young as 3 years spontaneously discover algorithms for addition which allow them to make counting decisions in the same way as chimpanzees. This is precocious knowledge manifesting at a developmental stage. How those mental mechanics work, in either chimps or children, is not understood. What is known is that chimps and humans both have similar sociality and have an innate ability for numeracy.
Innate aptitude may require a cultural kick for an ability to manifest. Because basic math is ubiquitous in modern societies, the common assumption is that humans naturally comprehend simple numeracy. That is not so. The Piraha tribe of hunter-gathers in Brazil cannot count at all. Their word for 1 also means “a few,” while 2 does double duty for “not many.” Anything else is simply “many.” They also have no way to say “more,” “several,” or “all.” American linguist Daniel Everett tried to teach the Pirahas math basics, but not a single Piraha could count to 10 or add 1 and 1 after 8 months of diligent instruction.
Pigeons are capable of high-order relational learning. ~ American psychologist Ed Wasserman
Chimps and people have nothing over pigeons, which readily absorb abstract numerical rules.
Despite completely different brain organization and hundreds of millions of years of evolutionary divergence, pigeons and monkeys solve ordinal number problems in a similar way. ~ American cognitive psychologist Elizabeth Brannon
Pigeon geographical sense is unerring. Thanks to detailed mental maps, pigeons can fly to a destination via the most efficacious route, taking into account the best food stops and watering holes. This is characteristic of birds, which typically have infallible navigational skills.
The homing ability of birds can be positively eerie. Birds can orient themselves based on visual landmarks, the Sun, and stars, and even by sense of smell, just like we can. Birds are also able to find their way using methods unimaginable to humans, such as magnetic fields, polarized light, echolocation, and infrasound. You can blindfold a bird, cover its nostrils, cover its ears, transport it far from home in a magnetized cage, and, more often than not, it will still manage to find its way home. The question becomes not how birds find their way, but how they ever manage to become lost (a rare occurrence). ~ American ornithologist Noah Strycker
Pigeons have impressive visual memory: able to remember hundreds of images for several years. Pigeons can generalize and discriminate among different painting styles. A trained pigeon can tell a Monet from a Picasso, and impressionism from cubism.
Once a pigeon understands the concept of a mirror, which has no analogue in Nature, it uses the mirror to examine parts of its body that it cannot ordinarily see. People are no different.
Pigeons can tell people who are kind to them from those that are not. No training needed for that.
Pigeons comprehend transitive inference, which is associative inferential reasoning. Knowing that A > B, B > C, C > D, and D > E, a pigeon cogently concludes that B > E. The grasp of transitive inference is essential to understanding the hierarchical social networks which characterize pigeon societies.
Pigeons plan. To do so, they assess their level of knowledge and seek more information if relevant facts are not known.
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All organisms have acumen adapted to their habitats. Before surveying animal intelligence, a brief review of other life.