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How do organisms such as tripod fish survive in permanent deep-sea darkness?

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Diagram showing ocean zonation by depth and region, with labeled layers: littoral, sublittoral, bathyal, abyssal, and hadal along the seafloor, and epipelagic, mesopelagic, bathypelagic, and abyssalpelagic in open water. The littoral zone is at the high-tide mark. Vertical scale marks photic and aphotic zones from surface to 10,000 meters. — Marine ecosystem Zonation of the ocean. Note that in the littoral zone the water is at the high-tide mark.

Organisms such as the tripod fish survive in the permanent darkness of the aphotic zone through specialized evolutionary adaptations to their extreme environment.12

While many deep-sea species utilize bioluminescence to attract prey, find mates, or disguise their form from predators, bottom-dwelling (benthic) organisms like the tripod fish typically lack these light-producing organs. Instead, these benthic forms are characterized by other specialized traits, such as smaller eyes and mouths that are often down-turned, which are suited to their life on the ocean floor.13

In the deep sea, where light is absent, survival depends on these unique physiological and behavioral specializations rather than visual hunting strategies. These organisms have evolved to thrive in conditions defined by extreme pressure and cold, occupying a habitat that is among the most specialized in the world.12