ABSTRACT
Information is essential for all forms of life — so it is important to understand how information is perceived, how it is stored, how it is passed on, and how it is used by organisms as they live and reproduce. In the world of photosynthetic microorganisms, where virtually all life depends on solar energy, light becomes a source of information, used to orient microorganisms spatially and to guide their movements or growth. The full exploitation of this information necessitates proper perceiving devices, able to change the small signal represented by the light falling upon them into a larger signal and response of an entirely different physical nature, i.e., these devices must perform perception, transduction, and amplification.
