bioluminescence Production of light, with very little heat, by some living organisms. Its biological function is varied: in some species, such as fireflies, it is a recognition signal in mating; in others, such as squids, it is a method of warding off predators; and in angler fish it is used to attract prey. The light-emitting substance (luciferin) in most species is an organic molecule that emits light when it is oxidized by molecular oxygen in the presence of an enzyme (luciferase).

bioluminescence The production by living organisms of light without heat. Bioluminescence is a property of many types of organism (e.g. certain (mostly marine) bacteria, dinoflagellates, and fireflies).