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How do some deep-sea fishes produce light in dark ocean waters?
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Diodon hystrix is a species of porcupine fish. These fishes are short and broad-bodied, with large eyes and spines covering their skin. Like puffer fishes, they inflate their bodies when threatened.
Deep-sea fishes produce light through a process called bioluminescence, which involves the chemical oxidation of a pigment known as luciferin in the presence of an enzyme called luciferase.1
There are two primary ways these fishes generate this light:
- Internal Biochemical Reaction: Many species produce light intracellularly within specialized cells called photocytes. These complex light organs, or photophores, often contain a lens, a reflector, and color filters to direct the light.23
- Symbiotic Bacteria: Some fishes harbor specific luminous bacteria within their light organs. The fish provides the bacteria with nutrients via a rich blood supply, while the fish controls the light output by using pigment granules or a membrane to cover the organ.3
These light displays serve critical survival functions, including attracting prey, acting as mating or species-recognition signals, and providing camouflage by matching the intensity of sunlight from above to hide the fish's shadow from predators below.23