Specialized networks of blood vessels in these organs encourage the growth of bacteria that continuously emit a cool, blue-green light. The front of each light organ is covered by a retractable fold of skin that can be snapped open and shut in a split second. By blinking them on and off, flashlight fish use their living lights to confound natural predators and net-wielding scientists alike. When a school is chased, each flashlight fish takes evasive action, first dashing in one direction with lights on and then blinking off while darting away on a completely different course. Each fish performs this 'flash and dash' behavior up to 75 times a minute.
Flashlight fish are the brightest of bioluminescent creatures.
Their schools produce so much light that along reefs of the politically tense Red Sea, that they have been shot at and bombed, apparently mistaken for night-operating frogmen equipped with diving lights. Bioluminescence may also facilitate finding potential mates of the appropriate species - especially among a host of other vertical migrators. Many creatures increase the frequency and intensity of bioluminescent displays during their mating period. Some biologists suspect that Columbus was witnessing the mass mating ritual of the bioluminescent Bermuda fire worm. This small, bottom-dwelling polychaete swarms near the ocean surface on summer evenings for a few nights following a full moon.