Senses
Bacteria possess highly developed sensory systems for the detection of nutrients, energy sources, and toxins, and the capacity to store and evaluate the manifold information provided by these diverse receptors. The final outcome of this sensory integration is the decision to continue swimming in the same direction or tumble into a different course. Thus, some of the most fundamental features of brains, such as sensory integration, memory, decision-making, and the control of behavior, can all be found in these simple organisms. ~ American neuroscientist John Morgan Allman
Bacteria are responsive to light (sight), have a sense of contact (touch), respond to chemicals through direct contact (taste) and through the air (smell).
Bacteria can sense up to some 50 different chemicals using proteins embedded in the outer membrane. A further network of some 12–14 proteins are involved in the interpretation and transduction of the signals to control swimming direction. ~ Anthony Trewavas
Meningococcus is the bacterium that causes meningitis. It uses 3 different temperature-sensing RNA molecules to watch for rising host temperature, which indicates an inflammation-activated immune response. This lets meningococcus anticipate and coordinate its processes to evade this immune system reaction.
Magnetospirillum, a freshwater and sediment dweller, has an uncommon fondness for ionic iron, which it ingests, enabling it to respond to magnetic fields. Magnetospirillum is but one of numerous magnetically sensitive bacteria.
