Abyssal zone
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The abyssal zone is the pelagic zone that contains the very deep benthic communities near the bottom of oceans. At depths of 2,000 to 6,000 meters (6,560 to 19,680 feet), this zone remains in perpetual darkness and never receives daylight. Its permanent inhabitants – for example, the Black swallower, tripod fish, deep-sea anglerfish, and the giant squid – are able to withstand the immense pressures of the ocean depths, up to 775 kilograms per square centimeter (76 megapascals or 4.92 long tons force per square inch). The deep trenches or fissures that plunge down thousands of feet below the ocean floor – for example, the midoceanic trenches such as the Marianas in the Pacific – are almost unexplored. Only the French bathyscaph Trieste has been able to descend to these depths. These regions are also characterized by continuous cold and lack of nutrients.
The area below the abyssal zone is the hadal zone and hardly any living creatures inhabit it. The zone above is the bathyal zone, and above that is the photic zone, in which the most of ocean life exists.
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