The
abyssal zone is the abyssopelagic layer of
pelagic zoneAny water in the sea that is not close to the bottom is in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means open sea....
that contains the very deep benthic communities near the bottom of
oceanAn ocean is a large body of saline water, and a principal component of the hydrosphere. Approximately 75% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
s. "Abyss" is from the
GreekGreek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
word meaning "bottomless sea". At depths of 4,000 to 6,000 meters (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. It is the deeper part of the
midnight zone which starts in the
bathyalpelagicThe bathyal zone or bathypelagic – from Greek βαθύς , deep – is the pelagic zone that extends from a depth of 1000 to 4000 meters below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The average temperature hovers at about . Although larger by volume than the...
waters above.
Its permanent inhabitants (for example, the
Black swallowerThe black swallower, Chiasmodon niger, is a species of deep sea fish in the family Chiasmodontidae, notable for its ability to swallow fish larger than itself...
,
tripod fishThe tripod fish, Bathypterois grallator, is a bathypelagic fish named for the long extensions of its pelvic and lower caudal fins, on which it stands on the sea floor...
, deep-sea
anglerfishAnglerfish are the members of the order Lophiiformes . They are bony fish named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfish are pelagic , others are benthic...
and the giant squid) are able to withstand the immense pressures of the ocean depths, up to .
The
abyssal zone is the abyssopelagic layer of
pelagic zoneAny water in the sea that is not close to the bottom is in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means open sea....
that contains the very deep benthic communities near the bottom of
oceanAn ocean is a large body of saline water, and a principal component of the hydrosphere. Approximately 75% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
s. "Abyss" is from the
GreekGreek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
word meaning "bottomless sea". At depths of 4,000 to 6,000 meters (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. It is the deeper part of the
midnight zone which starts in the
bathyalpelagicThe bathyal zone or bathypelagic – from Greek βαθύς , deep – is the pelagic zone that extends from a depth of 1000 to 4000 meters below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The average temperature hovers at about . Although larger by volume than the...
waters above.
Its permanent inhabitants (for example, the
Black swallowerThe black swallower, Chiasmodon niger, is a species of deep sea fish in the family Chiasmodontidae, notable for its ability to swallow fish larger than itself...
,
tripod fishThe tripod fish, Bathypterois grallator, is a bathypelagic fish named for the long extensions of its pelvic and lower caudal fins, on which it stands on the sea floor...
, deep-sea
anglerfishAnglerfish are the members of the order Lophiiformes . They are bony fish named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfish are pelagic , others are benthic...
and the giant squid) are able to withstand the immense pressures of the ocean depths, up to . Many abyssal creatures have underslung jaws to sift through the sand to catch food. The deep trenches or fissures that plunge down thousands of feet below the ocean floor (for example, the midoceanic trenches such as the
Mariana TrenchThe Mariana Trench is the deepest known part of the world's oceans, and the deepest location on the surface of the Earth's crust. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about long but has a mean width of only...
in the Pacific) are almost unexplored. Only the
bathyscapheA bathyscaphe is a free-diving self-propelled deep-sea diving submersible, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design....
TriesteThe Trieste was a Swiss-designed deep-diving research bathyscaphe with a crew of two, which reached a record-breaking depth of about , in the deepest part of any ocean on Earth, the Challenger Deep in the Mariana Trench, in January 1960....
, the
remote controlA remote control is a component of an electronics device, most commonly a television set, used for operating the device wirelessly from a short line-of-sight distance....
submarineA submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has only limited underwater capability...
KaikoKaikō was a deep-sea remotely operated underwater vehicle built by JAMSTEC, a Japanese company. It sampled bacteria from the ocean floor of the Challenger Deep in the Mariana Trench, the deepest location in the world. On 2 March 1996, Kaikō reached a depth of 10,897 m, marking the deepest dive...
and the
NereusNereus is a hybrid autonomous underwater vehicle built by the Woods Hole Oceanographic Institution . Constructed as a research vehicle to operate at depths of up to , it was designed to explore Challenger Deep, the deepest surveyed point in the global ocean...
have been able to descend to these depths. These regions are also characterized by continuous cold and lack of nutrients. The abyssal zone has temperatures around 2 to 3 degrees Celsius through the large majority of its mass.
The area below the Abyssal Zone is the sparsely inhabited
Hadal ZoneHadal zone , also known as trench zone or Hadopelagic zone, is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around to the bottom of the ocean....
. The zone above is the
Bathyal ZoneThe bathyal zone or bathypelagic – from Greek βαθύς , deep – is the pelagic zone that extends from a depth of 1000 to 4000 meters below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The average temperature hovers at about . Although larger by volume than the...
. These three zones belong to the deep-sea realm. Above on the continental platform there are respectively the euphotic and dysphotic zones. The Abyssal zone lies partially in the dysphotic and partially in the
aphotic zoneThe aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. Consequently, bioluminescence is essentially the only light found in this zone...
s.