The abyssopelagic zone biome comprises the marine water column below the bathypelagic zone biome at approximately 2500 -2700 m and extends either to the hadal pelagic zone biome (at approximately 6000 m) or to the benthopelagic zone biome within ca. 100 m of the seafloor. The depth of 2700 m may be critical for physiological reasons as the change in hydrostatic pressure across this depth may preclude organism migration.