Bioluminescence is the production of light by living organisms. Some single-celled organisms (bacteria and protista) as well as many multicellular animals and fungi demonstrate bioluminescence.

Light is produced by most bioluminescent organisms when a chemical called luciferin reacts with oxygen to produce light and oxyluciferin. The reaction between luciferin and oxygen is catalyzed by the enzyme luciferase. Luciferases, like luciferins, usually have different chemical structures in different organisms. In addition to luciferin, oxygen, and luciferase, other molecules (called cofactors) must be present for the bioluminescent reaction to proceed. Cofactors are molecules required by an enzyme (in this case luciferase) to perform its catalytic function. Common cofactors required for bioluminescent reactions are calcium and ATP, a molecule used to store and release energy that is found in all organisms.

The terms luciferin and luciferase were first introduced in 1885. The German scientist Emil du Bois-Reymond obtained two different extracts from...