Photophore
Photophores from a Splitfin Flashlight Fish can be seen from 100 ft away!
Photophores are organs that are used by fish (and invertebrates) to produce light either by chemical reaction or through symbiotic bacteria capable of bioluminescence. Most fish that use photophores live in the deep sea where light from the surface is limited. Like a firefly in the sea, some of these fish use photophores to attract mates; others use photophores as counterillumination and camouflage; others use their photophores like search lights to find prey or avoid predators; and still others use photophores for multiple purposes. Splitfin Flashlight Fish (Anomalops katoptron), for example, use their photophores to communicate with other flashlight fish, attract prey, and confuse predators. They are believed to produce the brightest bioluminescence of any organism – their light can be seen from over 100 feet away!
For other examples of fish with photophores, check out the “twinkle twinkle little fish” post on the Fisheries Blog!