In the ocean, the aphotic zone is sometimes referred to as the dark ocean. Depending on how it is defined, the aphotic zone of the ocean begins between depths of about to and extends to the ocean floor. The depth at which the aphotic zone begins in the ocean depends on many factors. In clear, tropical water sunlight can penetrate deeper and so the aphotic zone starts at greater depths. Around the poles, the angle of the sunlight means it does not penetrate as deeply so the aphotic zone is shallower. If the water is turbid, suspended material can block light from penetrating resulting in a shallower aphotic zone. Temperatures can range from roughly to .     See also Abyssal zone Benthic zone Hadal zone Pelagic zone Photic zone References  
In the ocean, the aphotic zone is sometimes referred to as the dark ocean. Depending on how it is defined, the aphotic zone of the ocean begins between depths of about to and extends to the ocean floor. The majority of the ocean is aphotic, with the average depth of the sea being 4267 m deep with the deepest part of the sea, being the Challenger Deep in the Mariana Trench, is about 11,000 m deep. The depth at which the aphotic zone begins in the ocean depends on many factors. In clear, tropical water sunlight can penetrate deeper and so the aphotic zone starts at greater depths. Around the poles, the angle of the sunlight means it does not penetrate as deeply so the aphotic zone is shallower. If the water is turbid, suspended material can block light from penetrating resulting in a shallower aphotic zone. Temperatures can range from roughly to . In some rare cases, bacteria use chemical energy sources such as sulfides and methane. Many of the animals in the aphotic zone are bioluminescent, meaning they can produce their light. Bioluminescence can be used both for navigation and luring small animals into their jaws. An excellent example of this is the angler fish, as it has a light lure protruding in front of its mouth from a unique appendage on its head which provides navigation and as bait for smaller animals. Some animals can cross between the photic and aphotic zones in search of food. For example, the sperm whale and the southern elephant seal occasionally hunt in the aphotic zone despite the water pressure squashing their bodies; however, not fatally. After sunset, millions of organisms swarm up from the depths to feed on the microorganisms peacefully floating in the warm epipelagic zone. Many copepods( a group of small crustaceans) and invertebrate larvae come up to shallower waters to eat the phytoplankton, which attracts many predators like squid, hatchet fish, and lantern fish. The migration of the many bioluminescent animals is visible to the naked eye. This nightly vertical migration is the largest (in terms of the number of animals) on our planet. The Migration of Bioluminescent Organisms from Aphotic Zone See also Abyssal zone Benthic zone Hadal zone Pelagic zone Photic zone References Which Animals Live in the Aphotic Zone of the Ocean? (infobloom.com) askabiologist.asu.edu/animals-open-ocean.
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majority of the ocean is aphotic, with the average depth of the sea being 4267 m deep with the deepest part of the sea, being the Challenger Deep in the Mariana Trench, is about 11,000 m deep. The depth
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In some rare cases, bacteria use chemical energy sources such as sulfides and methane. Many of the animals in the aphotic zone are bioluminescent, meaning they can produce their light. Bioluminescence can be used both for navigation and luring small animals into their jaws. An excellent example of this is the angler fish, as it has a light lure protruding in front of its mouth from a unique appendage on its head which provides navigation and as bait for smaller animals.
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Some animals can cross between the photic and aphotic zones in search of food. For example, the sperm whale and the southern elephant seal occasionally hunt in the aphotic zone despite the water pressure squashing their bodies; however, not fatally.
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After sunset, millions of organisms swarm up from the depths to feed on the microorganisms peacefully floating in the warm epipelagic zone. Many copepods( a group of small crustaceans) and invertebrate larvae come up to shallower waters to eat the phytoplankton, which attracts many predators like squid, hatchet fish, and lantern fish. The migration of the many bioluminescent animals is visible to the naked eye. This nightly vertical migration is the largest (in terms of the number of animals) on our planet.
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The Migration of Bioluminescent Organisms from Aphotic Zone
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Which Animals Live in the Aphotic Zone of the Ocean? (infobloom.com)
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askabiologist.asu.edu/animals-open-ocean.