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| Ocean habitats |
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| aquatic ecosystem |
| continental shelf |
| neritic zone |
| littoral zone |
| intertidal |
| pelagic zone |
| demersal zone |
| benthic zone |
| benthic life |
| coral reefs |
| estuaries |
| seamounts |
| fishing banks |
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Any 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. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly
It can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom, like the diagram on the left. A water column is a conceptual column of water from surface to bottom sediments Conditions change as you go deeper down the water column; the pressure increases and there is less light. Depending on the depth, scientists further subdivide the water column, rather like the earth's atmosphere is divided into different layers. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five
Contents |
Description
The pelagic zone occupies 1,370,000,000 cubic kilometres (330,000,000 cubic miles) and has a vertical range up to 11,000 metres (36,000 feet). Fish that live in the pelagic zone are called pelagic fish. Pelagic life decreases with increasing depth. It is affected by light levels, pressure, temperature, salinity, the supply of dissolved oxygen and nutrients, and the submarine topography.
In deep water the pelagic zone is sometimes called the open-ocean zone and can be contrasted with water that is near the coast or on the continental shelf. The coast is defined as the part of the land adjoining or near the Ocean. The continental shelf is the extended perimeter of each Continent and associated Coastal plain, which is covered during interglacial periods such However in other contexts, coastal water that is not near the bottom is still said to be in the pelagic zone.
The pelagic zone can be contrasted with the benthic and demersal zones at the bottom of the sea. The benthic zone is the ecological region at the lowest level of a Body of water such as an Ocean or a Lake, including the sediment surface and some sub-surface The demersal zone is the part of the Sea or Ocean (or deep Lake) comprising the Water column that is near to (and is significantly affected The benthic zone is the ecological region at the very bottom of the sea. It includes the sediment surface and some sub-surface layers. Marine organisms living in this zone, such as clams and crabs, are called benthos. Clam is a word which can be used for all some or only a few Species of Bivalve Mollusks the word is a Common name which has Crabs are decapod Crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (βραχύ / brachy Benthos are the organisms which live on in or near the Seabed, also known as the Benthic zone. The demersal zone is just above the benthic zone. It can be significantly affected by the seabed and the life that lives there. Fish that live in the demersal zone are called demersal fish. A demersal fish is a Fish that feeds on or near the bottom of the Ocean or a deep Lake in the Demersal zone. They are also called bottom feeders or groundfish. A bottom feeder is an Aquatic animal that feeds on or near the bottom of a body of water Groundfish are Fish that live on in or near the bottom of the body of water they inhabit
Depth and layers
Depending on how deep the sea is, there can be up to five vertical layers in the ocean. From the top down, they are:
Epipelagic (sunlit)
From the surface (MSL) down to around 200 m (656 ft). The photic zone or euphotic zone ( Greek 'well lit' is the depth of the water in a Lake or Ocean, that is exposed to sufficient Sunlight Mean sea level (MSL is the average (mean height of the Sea, with reference to a suitable reference surface
The illuminated surface zone where there is enough light for photosynthesis. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Due to this, plants and animals are largely concentrated in this zone. Nearly all primary food production in the ocean occurs here. Here one will typically encounter fish such as tuna and numerous amounts of sharks, as well as dolphin fish and jellyfish. Tuna, are several Species of ocean-dwelling Fish in the family Scombridae, mostly in the genus Thunnus. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body The Mahimahi (in Hawaiian Coryphaena hippurus, also known as common dolphin-fish, dorado maverikos, or lampuki (in Maltese Jellyfish are free-swimming members of the phylum Cnidaria. They have several different basic morphologies that represent several different cnidarian classes including the
Mesopelagic (twilight)
From 200 m down to around 1,000 m (3,280 ft). The mesopelagic ( Greek μέσον middle (also known as the middle pelagic or twilight zone) is a Pelagic zone extending from 200 m (650 ft
Although some light penetrates this deep, it is insufficient for photosynthesis. The name stems from Greek μέσον, middle. At about 500 m the water becomes depleted of oxygen. Still, an abundance of life copes with more efficient gills or minimal movement. Animals such as swordfish, squids, wolffish, a few species of cuttlefish, and other semi-deepsea creatures live here. Swordfish ( Xiphias gladius) are large highly migratory Predatory Fish characterized by a long flat bill. Squid are marine Cephalopods of the order Teuthida, which comprises around 300 species The Atlantic wolffish ( Anarhichas lupus) also known as the Seawolf, Atlantic catfish, wolf eel (the common name for its Pacific Cuttlefish are marine animals of the order Sepiida belonging to the Cephalopoda class (which also includes Squid, Octopuses
Bathypelagic (dark)
From 1,000 m down to around 4,000 m (13,123 ft). The bathyal zone or bathypelagic – from Greek βαθύς (bathýs deep – is the Pelagic zone that extends from a depth of 1000 to 4000
By this depth the ocean is almost entirely dark (with only the occasional thermoluminescence organism, such as lanternfish). Luminescence is also the title of an album by singer Anggun. Luminescence is Light not generated by high temperatures alone Lanternfishes (or myctophids, from the Greek mykter, "nose" and ophis, "serpent" are small Deep sea fish of There are no living plants, and most animals survive by consuming the snow of detritus falling from the zones above or (like the marine hatchet fish) by preying upon others. In the deep ocean marine snow is a continuous shower of mostly organic Detritus falling from the upper layers of the water column In Biology, detritus is non-living particulate organic material (as opposed to dissolved organic material Marine hatchetfish are big deep-sea Bathypelagic Fish of the family Sternoptychidae, together with Bottlelights Pearlsides Giant squid (as well as smaller squids & Dumbo octopuses ) live at this depth, and here they are hunted by deep-diving sperm whales. The giant squid ( Genus: Architeuthis) is a deep-ocean dwelling Squid in the family Architeuthidae, represented by Squid are marine Cephalopods of the order Teuthida, which comprises around 300 species The Octopuses of the Genus Grimpoteuthis are also known as " Dumbo octopuses" from the ear-like fins protruding from the top of The Sperm Whale ( Physeter macrocephalus or Physeter catodon) is the largest of all Toothed whales and largest living toothed animal From Greek βαθύς (baths), deep.
Abyssopelagic
From 4,000 m down to above the ocean floor. The abyssal zone is the abyssopelagic layer of Pelagic zone that contains the very deep Benthic communities near the bottom of Oceans "Abyss"
No light whatsoever penetrates to this depth. The name is derived from the Greek άβυσσος (ábyssos), abyss, meaning bottomless (a holdover from the times when the deep ocean was believed to be bottomless).
Hadopelagic
The deep water in ocean trenches. Hadal zone or (trench zone (Greek for "like Hades," in other words "unseen" or Hadopelagic zone is the delineation for the deepest
The name is derived from the Greek Άιδης (Haidēs), Hades, the classical Greek underworld. Hades (from Greek, Hadēs, originally, Haidēs or, Aidēs, probably from Indo-European *n̥-wid- 'unseen' refers both to the ancient This zone is mostly unknown, and very few species are known to live here (in the open areas). However, many organisms live in hydrothermal vents in this and other zones. A hydrothermal vent is a Fissure in a planet's surface from which geothermally heated Water issues Some define the hadopelagic as waters below 6,000 m (19,685 ft), whether in a trench or not.
The bathypelagic, abyssopelagic, and hadopelagic zones are very similar in character, and some marine biologists elide them into a single zone or consider the latter two to be the same. Marine biology is the scientific study of living Organisms in the Ocean or other marine or Brackish bodies of water
See also
- Photic zone (Sunlit zone)
- Aphotic zone (Twilight zone)
- Neritic zone
External links
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