Ocean Zones

Organisms found in the aphotic zones of the pelagic realm, the bathypelagic zone (about 3,000-13,000 ft [1,000-4,000 m]), the abyssopelagic zone (about 13,000-20,000 ft [4,000-6,000 m]), and the hadalpelagic zone (below 20,000 ft [6,000 m]), have evolved some bizarre adaptations for survival in their lightless environment. In these regions, pressures may exceed 500 atmospheres—500 times that of atmospheric pressure, or the equivalent of several tons per square inch—and temperatures never get much warmer than about 3°C (37°F). Organisms within these zones generally prey on each other and have developed special features such as expandable mouths, large and very sharp teeth, and special strategies for hunting or luring prey.