Which Animals Live in the Aphotic Zone of the Ocean?
Most of the ocean is completely dark. This is called the aphotic zone. The aphotic zone begins at a depth of 0.9 km (3,000 ft) and continues to the bottom, which usually maxes out at a depth of 5.5 km (18,000 ft), except for ocean trenches, which can be as deep as 11 km (6.8 mi). In the aphotic zone, photosynthesis cannot occur, so the usual foundation of food webs, plants and cyanobacteria, are absent. Instead, animals have to subsist on carcasses that fall from above, other animals, and in some rare cases, bacteria that use chemical energy sources such as sulfides and methane. The aphotic zone is further broken into two levels, the bathypelagic zone, which extends from around 1 km (3300 ft) below the surface to 4 km (13000 ft) below. Below this is the abyssopelagic zone, also called the abyssal zone, where pressures are extremely high (400 atmospheres and up) and biodiversity drops sharply. Even below the abyssopelagic zone is the hadopelagic zone, which is used to refer to ocean tre
