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What are photophores in lanternfish and hatchetfish?
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Bioluminescence
Time-lapse image of fireflies in the Catskill Mountains, New York. Firefly light is a cold light, with approximately 100 percent of the energy given off as light and only a minute amount as heat. Only light in the visible spectrum is emitted.
In lanternfish and hatchetfish, photophores are specialized light-emitting organs that produce light through a chemical reaction involving the oxidation of luciferin by the enzyme luciferase in the presence of oxygen.123
These organs are typically located on the ventral and lateral surfaces of the fish, allowing light to be emitted downward and outward. This positioning is believed to serve several critical functions:1
- Counter-illumination: By matching the intensity of sunlight penetrating from above, the fish can conceal its own shadow from predators lurking below.1
- Recognition: The distinct arrangements of photophores on the body may serve as specific patterns for species and sex recognition.1
- Survival: Like other deep-sea fishes, these organisms may use their light to frighten predators or navigate the darkness of the deep ocean.1
Structurally, photophores are glandular and can be quite complex, often containing lenses, filters, and reflecting layers to refine the light produced by the chemical reaction.3