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The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word abyss comes from the Greek word ἄβυσσος ( ábussos ), meaning "bottomless". [ 1 ] At depths of 4,000–6,000 m (13,000–20,000 ft), [ 2 ] this zone remains in perpetual darkness.
The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor. A marine food web is a food web of marine life. At the base of the ocean food web are single-celled algae and other plant-like organisms known as phytoplankton.
The abyssal zone remains in perpetual darkness at a depth of 4,000 to 6,000 metres (13,000 to 20,000 ft). [23] The only organisms that inhabit this zone are chemotrophs and predators that can withstand immense pressures, sometimes as high as 76 megapascals (750 atm; 11,000 psi).
Historically, the hadal zone was not recognized as distinct from the abyssal zone, although the deepest sections were sometimes called "ultra-abyssal".During the early 1950s, the Danish Galathea II and Soviet Vityaz expeditions separately discovered a distinct shift in the life at depths of 6,000–7,000 m (20,000–23,000 ft) not recognized by the broad definition of the abyssal zone.
In zoology, deep-sea gigantism or abyssal gigantism is the tendency for species of deep-sea dwelling animals to be larger than their shallower-water relatives across a large taxonomic range. Proposed explanations for this type of gigantism include necessary adaptation to colder temperature, food scarcity, reduced predation pressure and ...
The sea surface microlayer (SML) at the air-sea interface is a distinct, under-studied habitat compared to the subsurface and copepods, important components of ocean food webs, have developed key adaptations to exploit this niche. [40] The ocean-spanning SML forms the boundary between the atmosphere and the hydrosphere.
A freshwater aquatic food web. The blue arrows show a complete food chain (algae → daphnia → gizzard shad → largemouth bass → great blue heron). A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community.
Psychropotes longicauda is a cosmopolitan abyssal species of sea cucumber and is found on the seabed throughout the world's deep oceans. Its larva is pelagic and is often found more than 500 m (1,600 ft) above the ocean floor but still in the abyssal zone .