Biological light is created by an enzyme-catalyzed chemoluminescence reaction, where a luciferin is oxidized by a luciferase. ATP is usually involved. The reaction can either be external to cells, or an intracellular. There are 33 known species of worms that produce bioluminescence. Bioluminescence is also found in fungus, beetles, and millipedes.
Answer provided by a Billings West High School Student