The phenomenon of bioluminescence—visible light emitted by organisms—is rare on land compared with its diverse manifestations in the oceans. Most of the terrestrial representatives are insects, followed by bioluminescent fungi and a few earthworms, millipedes, centipedes, and snails. Beetles (Coleoptera) make up the majority of the bioluminescent insects, with more than 2000 reported species, mostly tropical in distribution.