Aphotic zone

Most food in this zone comes from dead organisms sinking to the bottom of the lake or ocean from overlying waters.

The depth of the aphotic zone can be greatly affected by such things as turbidity and the season of the year.

In clear, tropical water sunlight can penetrate deeper and so the aphotic zone starts at greater depths.

If the water is turbid, suspended material can block light from penetrating, resulting in a shallower aphotic zone.

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.

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.

[9] After sunset, millions of organisms swarm up from the depths to feed on the microorganisms floating in the warm epipelagic zone.

Many copepods and invertebrate larvae come up to shallower waters to eat the phytoplankton, which attracts many predators like squid, hatchetfish, and lantern fish.