A form of chemiluminescence happening in living organisms. Chemiluminescence refers to chemical reactions in which the energy produced is given off not as heat but as light. The most familiar example of this "cold light" is the firefly (Coleoptera: Lampyridae family), which use an enzyme called luciferase that triggers a light-emitting reaction, making the insect's lower abdomen glow. Some fungi and earthworms also use bioluminescence, but it is most common in the oceans where fish and worms have glowing organs and use the produced light as a decoy or sometimes as a bait.