The emission of light without heat by living organisms
It occurs in glow-worms and fireflies, bacteria and
fungi, and in many deep-sea fish; in animals it may
serve as a means of protection (e.g. by disguising
the shape of a fish) or species recognition or it
may provide mating signals.
The light is produced
during the oxidation of a compound called luciferin,
the reaction being catalysed by an enzyme, luciferase.
It may be continuous (e.g. in bacteria) or intermittent
(e.g. in fireflies)