Most deep-sea animals glow in the dark

Many are probably familiar with pictures of monstrous deep-sea angler fish luring prey directly into the mouth with the help of a special “float” filled with luminous bacteria. The bait shines in the darkness due to bioluminescence, chemical processes that release energy in the form of light.

For a long time, scientists believed that this property is rare in living beings, but a new study published in Scientific Reports, which is in fact the first quantitative analysis of bioluminescence in deep water, suggests that almost ¾ of all animals that live at a depth of 1 to 4000 meters, can shine. Fish, jellyfish, worms, larvae, crustaceans, squids and octopuses also possess this talent.

There are many ways to glow in the dark waters. Some resort to the help of bacteria-symbionts, others (for example, jellyfish) use for this purpose special chemical processes. Light can serve both to lure the prey, and to deter predators and attract partners for mating. This diversity, according to scientists, and makes bioluminescence a feature that most of the animals that live in deep water seek to possess.