Unobstructed water in the body of the sea that is neither close to the surface nor to the sea floor
"Pelagic" and "Open sea" redirect here. For the writer, see Vasa Pelagić. For the marketplace, see OpenSea. For ocean not controlled by any sovereign territory, also called the "high seas", see International waters.
Layers of the pelagic zone (scaled)
Marine habitats
Coastal habitats
Littoral zone
Intertidal zone
Estuaries
Mangrove forests
Seagrass meadows
Kelp forests
Coral reefs
Continental shelf
Neritic zone
Ocean surface
Surface microlayer
Epipelagic zone
Open ocean
Pelagic zone
Oceanic zone
Sea floor
Seamounts
Hydrothermal vents
Cold seeps
Demersal zone
Benthic zone
Marine sediment
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The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient Greek πέλαγος (pélagos) 'open sea'.[1] The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients (such as iron, magnesium and calcium) all change. Somewhat analogous to stratification in the Earth's atmosphere, but depending on how deep the water is, the water column can be divided vertically into up to five different layers (illustrated in the diagram).
Marine life is affected by bathymetry (underwater topography) such as the seafloor, shoreline, or a submarine seamount, as well as by proximity to the boundary between the ocean and the atmosphere at the ocean surface, which brings light for photosynthesis, predation from above, and wind stirring up waves and setting currents in motion. The pelagic zone refers to the open, free waters away from the shore, where marine life can swim freely in any direction unhindered by topographical constraints.
The oceanic zone is the deep open ocean beyond the continental shelf, which contrasts with the inshore waters near the coast, such as in estuaries or on the continental shelf. Waters in the oceanic zone plunge to the depths of the abyssopelagic and further to the hadopelagic. Coastal waters are generally the relatively shallow epipelagic. Altogether, the pelagic zone occupies 1,330 million km3 (320 million mi3) with a mean depth of 3.68 km (2.29 mi) and maximum depth of 11 km (6.8 mi).[2][3][4] Pelagic life decreases as depth increases.
The pelagic zone contrasts with the benthic and demersal zones at the bottom of the sea. The benthic zone is the ecological region at the very bottom, including the sediment surface and some subsurface layers. Marine organisms such as clams and crabs living in this zone are called benthos. Just above the benthic zone is the demersal zone. Demersal fish can be divided into benthic fish, which are denser than water and rest on the bottom, and benthopelagic fish, which swim just above the bottom. Demersal fish are also known as bottom feeders and groundfish.
^"pelagic (adj.)". Online Etymology Dictionary. Retrieved 17 February 2020.
^Costello, Mark John; Cheung, Alan; De Hauwere, Nathalie (2010). "Surface Area and the Seabed Area, Volume, Depth, Slope, and Topographic Variation for the World's Seas, Oceans, and Countries". Environmental Science & Technology. 44 (23): 8821–8. Bibcode:2010EnST...44.8821C. doi:10.1021/es1012752. PMID 21033734.
^Charette, Matthew; Smith, Walter (2010). "The Volume of Earth's Ocean". Oceanography. 23 (2): 112–4. doi:10.5670/oceanog.2010.51. hdl:1912/3862.
^Ocean's Depth and Volume Revealed Archived 23 August 2011 at the Wayback Machine OurAmazingPlanet, 19 May 2010.
The pelagiczone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient...
predominantly a pelagic species but forms large aggregations near the seabed when it spawns on banks of gravel. Two types of fish inhabit the demersal zone: those...
The abyssal zone or abyssopelagic zone is a layer of the pelagiczone of the ocean. The word abyss comes from the Greek word ἄβυσσος (ábussos), meaning...
Pelagic fish live in the pelagiczone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that...
that are commonly assumed to reside in the pelagiczone often rely heavily on resources from the littoral zone. Littoral areas of ponds and lakes are typically...
The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagiczone that lies between the photic...
submarine ridges and deep ocean trenches known as the hadal zone. For comparison, the pelagiczone is the descriptive term for the ecological region above...
of the number of animals) on our planet. Abyssal zone Benthic zone Hadal zonePelagiczone Photic zone Earle, Sylvia A.; Thorne-Miller, Boyce (1999). The...
The sunlight zone is 200 meters deep.The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that...
species of sea slug in the genus Glaucus. These sea slugs live in the pelagiczone (open ocean), where they float upside-down by using the surface tension...
bioluminescent organisms across the pelagic water column. The dispersal of bioluminescence across different depths in the pelagiczone has been attributed to the...
pelagiczone. Within the neritic, marine biologists also identify the following:[citation needed] The infralittoral zone is the algal-dominated zone down...
The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of 1,000 to 4,000 m (3...
intertidal zone or foreshore is the area above water level at low tide and underwater at high tide: in other words, the part of the littoral zone within the...
the Bay Area. Habitat loss at the edges of the pelagiczone is thought to create a loss of native pelagic fish species, by increasing vulnerability to predation...
the oceanic zone. The open ocean is vertically divided into four zones: the sunlight zone, twilight zone, midnight zone, and abyssal zone. The Mesopelagic...
move. Most colonies are long, thin, transparent floaters living in the pelagiczone. Like other hydrozoans, some siphonophores emit light to attract and...
some inhabit freshwater environments and, with the exception of the pelagiczone, marine environments as well. They comprise over 110,000 named species...
contrasted with holoplankton, which are planktonic organisms that stay in the pelagiczone as plankton throughout their entire life cycle. After a period of time...
large predatory fish. See forage fish. Bathypelagic – the open ocean or pelagiczone that extends from a depth of 1000 to 4000 meters below the ocean surface...
split the ocean into vertical and horizontal zones based on physical and biological conditions. The pelagiczone is the open ocean's water column from the...
seasonally stratified. Ponds and pools have two regions: the pelagic open water zone, and the benthic zone, which comprises the bottom and shore regions. Since...
of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone are subject to the legal regime of transit...
gastropod mollusk species. Holoplankton dwell in the pelagiczone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton...
at higher elevations on warmer equator-facing slopes. Because the alpine zone is present only on mountains, much of the landscape is rugged and broken...
seagrass meadows, tidepools, muddy, sandy and rocky seabeds, and the open pelagiczone. The organisms living in the sea range from whales 30 metres (98 feet)...
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