Ocean 22212 225040651 2008-07-11T16:29:32Z 78.154.204.138 wrong word [[Image:World ocean map.gif|right|thumb|240px|Animated map exhibiting the world's oceanic waters. A continuous body of water encircling the [[Earth]], the [[World Ocean|world (global) ocean]] is divided into a number of principal areas. Five oceanic divisions are usually recognized: [[Pacific Ocean|Pacific]], [[Atlantic Ocean|Atlantic]], [[Indian Ocean|Indian]], [[Arctic Ocean|Arctic]], and [[Southern Ocean|Southern]]; the last two listed are sometimes consolidated into the first three.]] {{Five oceans}} {{otheruses}} An '''ocean''' (from [[Greek language|Greek]] {{polytonic|''Ωκεανός''}}, [[Oceanus|''Okeanos'' (Oceanus)]]) is a major body of [[Seawater|saline water]], and a principal component of the [[hydrosphere]]. Approximately 71% of the [[Earth]]'s [[surface]] (an area of some 361 million [[square kilometre|square kilometer]]s) is covered by ocean, a [[World Ocean|continuous body of water]] that is customarily divided into several principal oceans and smaller [[sea]]s. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic [[salinity]] is around 35 [[parts per thousand]] (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. ==Overview== Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the [[World Ocean]] or global ocean.<ref>"[http://www.answers.com/Ocean#Encyclopedia Ocean]". ''The Columbia Encyclopedia.'' 2002. New York: Columbia University Press</ref><ref name="UNAoO">"[http://www.oceansatlas.com/unatlas/about/physicalandchemicalproperties/background/seemore1.html Distribution of land and water on the planet]". ''[http://www.oceansatlas.com/ UN Atlas of the Oceans]</ref> This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to [[oceanography]].<ref>Spilhaus, Athelstan F. 1942 (Jul.). "Maps of the whole world ocean." ''Geographical Review'' ([[American Geographical Society]]). Vol. 32 (3): pp. 431-5.</ref> The major oceanic divisions are defined in part by the [[continent]]s, various [[archipelago]]s, and other criteria: these divisions are (in descending order of size) the [[Pacific Ocean]], the [[Atlantic Ocean]], the [[Indian Ocean]], the [[Southern Ocean]] (which is sometimes subsumed as the southern portions of the Pacific, Atlantic, and Indian Oceans), and the [[Arctic Ocean]] (which is sometimes considered a [[sea]] of the Atlantic). The Pacific and Atlantic may be further subdivided by the [[equator]] into [[north]]erly and [[south]]erly portions. Smaller regions of the oceans are called [[sea]]s, [[Headlands and bays|gulfs]], [[bay]]s and other names. There are also some smaller bodies of saltwater that are on land and ''not'' interconnected with the World Ocean, such as the [[Aral Sea]], and the [[Great Salt Lake]] – though they may be referred to as 'seas', they are actually [[salt lake]]s. There are five oceans of the world: the [[Pacific Ocean]] the largest and deepest ocean of the world, the Atlantic Ocean the second largest and deepest ocean of the world, the Indian Ocean, the Southern Ocean, and the Arctic Ocean the smallest and shallowest ocean of the world. The oceans cover ¾ of the earth’s surface and have great impact on the biosphere. The evaporation of these oceans is how we get most of our rainfall, and their temperature determines our climate and wind pattern. Life within the ocean had already evolved 3 billion years prior to the movement of animal and plant life on land. The amount of life and distance from shore (abiotic factor) effects the major distribution of marine biomes. Animals such as algae, branacles and muscles who live within the intertidal zone (land meets ocean) will fix themselves to rocks so they do not get washed from the resulting tides. The ocean is home to many species and consists of several other zones such as pelagic, benthic (sea floor), photic, and aphotic.<ref>''Biology: Concepts & Connections.'' Chapter 34: The Biosphere: An Introduction to Earth's Diverse Environments (sec 34.7)</ref> Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic [[basalt]] that covers the Earth's [[mantle (geology)|mantle]] where there are no continents. From this perspective, there are three oceans today: the World Ocean and the Caspian and [[Black Sea]]s, the latter two having been formed by the collision of [[Cimmerian plate|Cimmeria]] with [[Laurasia]]. The [[Mediterranean Sea]] is very nearly a discrete ocean, being connected to the World Ocean through the [[Strait of Gibraltar]], and indeed several times over the last few million years [[plate tectonics|movement]] of the [[Africa|African continent]] has closed the strait off entirely. The Black Sea is connected to the Mediterranean through the [[Bosporus]], but this is in effect a natural [[canal]] cut through continental rock some 7,000 years ago, rather than a piece of oceanic sea floor like the Strait of Gibraltar. ==Physical properties== {{See|Sea water}} The area of the World Ocean is 361 million square kilometers (139 million sq mi),<ref name=encarta>{{cite web | publisher = Encarta | title = The World's Oceans and Seas | url = http://encarta.msn.com/media_461547746/The_World's_Oceans_and_Seas.html }}</ref> its volume is approximately 1.3 billion cubic kilometers (310 million cu mi)<ref>{{cite web | last = Qadri | first = Syed | title = Volume of Earth's Oceans | work = The Physics Factbook | year = 2003 | url = http://hypertextbook.com/facts/2001/SyedQadri.shtml | accessdate = 2007-06-07 }}</ref>, and its average depth is 3,790 meters (12,430 ft).<ref name=encarta /> Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep.<ref name="UNAoO" /> The vast expanses of deep ocean (anything below 200m) cover about 66% of the Earth's surface.<ref>{{cite web | last = Drazen | first = Jeffrey C. | title = Deep-Sea Fishes | publisher = School of Ocean Earth Science and Technology, University of University of Hawai{{okina}}i at Mānoa | url = http://www.soest.hawaii.edu/oceanography/faculty/drazen/fishes.htm | accessdate = 2007-06-07 }}</ref> This does not include seas not connected to the World Ocean, such as the [[Caspian Sea]]. The total mass of the [[hydrosphere]] is about 1.4 × 10<sup>21</sup> kilograms, which is about 0.023% of the Earth's total mass. Less than 2% is [[freshwater]]; the rest is [[saltwater]], mostly in the ocean. ===Color === {{main|Color of water}} A common misconception is that the oceans are blue primarily because the sky is blue. In fact, [[water]] has a very slight blue color that can only be seen in large volumes. While the sky's reflection does contribute to the blue appearance of the surface, it is not the primary cause.<ref>[http://amasci.com/miscon/miscon4.html#watclr BAD PHYSICS: Misconceptions spread by K-6 Grade School Textbooks<!-- Bot generated title -->]</ref> The primary cause is the absorption by the [[water]] molecules' nuclei of red photons from the incoming light, the only known example of color in nature resulting from vibrational, rather than electronic, dynamics.<ref>Braun, C. L. and Smirnov, S. N. (1993) [http://www.dartmouth.edu/~etrnsfer/water.htm Why is water blue?] ''J. Chem. Edu.'' '''70''', 612.</ref> ===Glow=== A number of sailors and professional mariners have reported that the ocean often emits a visible glow, or luminescence, which extends for miles at night. In 2005, scientists announced that for the first time, photographic evidence had been obtained of this glow. <ref> [http://www.livescience.com/strangenews/051004_sea_glow.html Mystery Ocean Glow Confirmed in Satellite Photos], By Robert Roy Britt, LiveScience Managing Editor, October 4, 2005. </ref> It may be due to [[bioluminescence]]. ==Exploration== {{main|Ocean exploration}} [[Image:Ocean gravity map.gif|right|thumb|350px|Map of large underwater features. (1995, [[NOAA]])]] Travel on the surface of the ocean through the use of boats dates back to prehistoric times, but only in modern times has extensive underwater travel become possible. The deepest point in the ocean is the [[Marianas Trench]] located in the Pacific Ocean near the [[Northern Mariana Islands]]. It has a maximum depth of 10,923&nbsp;meters (35,838 ft) <ref>[http://www.rain.org/ocean/ocean-studies-challenger-deep-mariana-trench.html Ocean Studies - RAIN<!-- Bot generated title -->]</ref><!--- Could be 35838.0&nbsp;±&nbsp;0.5&nbsp;ft is 10923.27-10923.57 m --->. It was fully surveyed in 1951 by the British naval vessel, "Challenger II" which gave its name to the deepest part of the trench, the "[[Challenger Deep]]". In 1960, the [[Bathyscaphe Trieste|Trieste]] successfully reached the bottom of the trench, manned by a crew of two men. Much of the bottom of the world's oceans are unexplored and unmapped. A global image of many underwater features larger than 10&nbsp;kilometers (6 mi) was created in 1995 based on gravitational distortions of the nearby sea surface. ==Regions== [[Image:Oceanic divisions.svg|400px|thumb|The major oceanic divisions]]Oceans are divided into numerous regions depending on the physical and biological conditions <!-- 'of' is hidden behind the picture, preview is showing correctly but saved version is not correct. Please see it, I am unable to correct it. -->of these areas. The [[pelagic zone]] includes all open ocean regions, and can be subdivided into further regions categorized by depth and light abundance. The [[photic zone]] covers the oceans from surface level to 200 meters down. This is the region where the photosynthesis most commonly occurs and therefore contains the largest biodiversity in the ocean. Since plants can only survive with photosynthesis any life found lower than this must either rely on material floating down from above (see [[marine snow]]) or find another primary source; this often comes in the form of [[hydrothermal vents]] in what is known as the [[aphotic zone]] (all depths exceeding 200m). The pelagic part of the photic zone is known as the [[epipelagic]]. The pelagic part of the aphotic zone can be further divided into regions that succeed each other vertically. The [[mesopelagic]] is the uppermost region, with its lowermost boundary at a [[thermocline]] of 12°C, which, in the tropics generally lies between 700 and 1,000 m. After that is the [[bathypelagic]] lying between 10°C and 4°C, or between 700 or 1,000 m and 2,000 or 4,000 m. Lying along the top of the abyssal plain is the [[abyssal zone|abyssalpelagic]], whose lower boundary lies at about 6,000 m. The final zone falls into the oceanic trenches, and is known as the [[hadal zone|hadalpelagic]]. This lies between 6,000 m and 10,000 m and is the deepest oceanic zone. Along with pelagic aphotics zones there are also [[benthic]] aphotic zones, these correspond to the three deepest zones. The [[bathyal zone]] covers the continental slope and the rise down to about 4,000 m. The [[abyssal]] zone covers the abyssal plains between 4,000 and 6,000 m. Lastly, the [[hadal]] zone corresponds to the hadalpelagic zone which is found in the oceanic trenches. The pelagic zone can also be split into two subregions, the [[neritic zone]] and the [[oceanic zone]]. The neritic encompasses the water mass directly above the [[continental shelves]], while the oceanic zone includes all the completely open water. In contrast, the [[littoral zone]] covers the region between low and high tide and represents the transitional area between marine and terrestrial conditions. It is also known as the [[intertidal]] zone because it is the area where tide level affects the conditions of the region. ==Climate effects== One of the most dramatic forms of [[weather]] occurs over the oceans: [[tropical cyclone]]s (also called "typhoons" and "hurricanes" depending upon where the system forms). [[Ocean current]]s greatly affect the Earth's climate by transferring warm or cold air and precipitation to coastal regions, where they may be carried inland by winds. The [[Antarctic Circumpolar Current]] encircles that continent, influencing the area's climate and connecting currents in several oceans. ==Ecology== Lifeforms native to oceans include (among others): *[[Radiata]] *[[Fish]] *[[Cetacea]] such as [[whale]]s, [[dolphin]]s and [[porpoise]]s, *[[Cephalopod]]s such as the [[octopus]] *[[Crustacean]]s such as [[lobster]]s and [[shrimp]] *[[Marine worm]]s *[[Plankton]] *[[Krill]] *[[Echinoderms]] (brittle star, starfish, sea cucumber, sand dollar) ==Economy== The oceans are essential to transportation: most of the world's goods are moved by [[ship]] between the world's [[seaport]]s. Important [[ship canal]]s include the [[Saint Lawrence Seaway]], [[Panama Canal]], and [[Suez Canal]]. They are also an important source of valuable food items for the [[fishing industry]]. Some of these are [[shrimp]], [[fish]], [[crabs]] and [[lobster]]. ==Ancient oceans== [[Image:Ocean-birth hg.png|thumb|Genesis of an ocean]] [[Continental drift]] has reconfigured the Earth's oceans, joining and splitting ancient oceans to form the current oceans. Ancient oceans include: *[[Bridge River Ocean]], the ocean between the ancient [[Insular Islands]] and [[North America]]. *[[Iapetus Ocean]], the southern hemisphere ocean between [[Baltica]] and [[Avalonia]]. *[[Panthalassa]], the vast world ocean that surrounded the [[Pangaea]] supercontinent. *[[Rheic Ocean]] *[[Slide Mountain Ocean]], the ocean between the ancient [[Intermontane Islands]] and North America. *[[Tethys Ocean]], the ocean between the ancient continents of [[Gondwana]] and [[Laurasia]]. *[[Khanty Ocean]], the ocean between Baltica and Siberia. *[[Mirovia]], the ocean that surrounded the [[Rodinia]] supercontinent. *[[Paleo-Tethys Ocean]], the ocean between Gondwana and the Hunic terranes. *[[Proto-Tethys Ocean]], *[[Pan-African Ocean]], the ocean that surrounded the [[Pannotia]] supercontinent. *[[Superocean]], the ocean that surrounds a global supercontinent. *[[Ural Ocean]], the ocean between [[Siberia]] and [[Baltica]]. ==Extraterrestrial oceans== :See also ''[[Extraterrestrial liquid water]]'' Earth is the only known [[planet]] with liquid water on its surface and is certainly the only one in our own [[solar system]]. However, liquid water is thought to be present under the surface of the [[Galilean moon]]s [[Europa (moon)|Europa]] and, with less certainty, [[Callisto (moon)|Callisto]] and [[Ganymede (moon)|Ganymede]]. [[Geyser]]s have been found on [[Enceladus (moon)|Enceladus]], though these may not involve bodies of liquid water. Other icy moons may have once had internal oceans that have now frozen, such as [[Triton (moon)|Triton]]. The planets [[Uranus (planet)|Uranus]] and [[Neptune (planet)|Neptune]] may also possess large oceans of liquid water under their thick atmospheres, though their internal structure is not well understood at this time. There is currently much debate over whether [[Mars (planet)|Mars]] once had an ocean of water in its northern hemisphere, and over what happened to it if it did; recent findings by the [[Mars Exploration Rover]] mission indicate it had some long-term standing water in at least one location, but its extent is not known. Astronomers believe that [[Atmosphere of Venus|Venus]] had liquid water and perhaps oceans in its very early history. If they existed, all trace of them seems to have vanished in later [[Geology of Venus|resurfacing]]. Liquid hydrocarbons are thought to be present on the surface of [[Titan (moon)|Titan]], though it may be more accurate to describe them as "lakes" rather than an "ocean." The [[Cassini-Huygens]] space mission initially discovered only what appeared to be dry lakebeds and empty river channels, suggesting that Titan had lost what surface liquids it might have had. A more recent fly-by of Titan made by Cassini has produced radar images that strongly suggest hydrocarbon lakes near the polar regions where it is colder. Titan is also thought likely to have a subterranean water ocean under the mix of ice and hydrocarbons that forms its outer crust. Beyond the solar system, [[Gliese 581 c]] is at the right distance from its sun for liquid water to exist on the planet's surface. Since it does not transit its sun, there is no way to know if there is any water there. [[HD 209458b]] may have water vapour in its atmosphere--this is currently being disputed. [[Gliese 436 b]] is believed to have "hot ice." Neither of these planets are cool enough for liquid water--but if water molecules exist there, they are also likely to be found on planets at a suitable temperature.<ref>''Hot "ice" may cover recently discovered planet'' [http://in.today.reuters.com/news/newsArticle.aspx?type=worldNews&storyID=2007-05-17T114149Z_01_NOOTR_RTRJONC_0_India-298599-1.xml&archived=False]</ref> ==Mythology== The original concept of "ocean" goes back to notions of [[Mesopotamian mythology|Mesopotamian]] and [[Proto-Indo-European mythology|Indo-European]] mythology, imagining the world to be encircled by a great river. ''[[Okeanos]]'', "Ωκεανός" in [[Greek mythology|Greek]], reflects the ancient Greek observation that a strong current flowed off [[Gibraltar]] and their subsequent assumption that it was a great river. (Compare also ''[[Samudra]]'' from [[Hindu mythology]] and [[Jörmungandr]] from [[Norse mythology]].) The world was imagined to be enclosed by a [[celestial ocean]] above the heavens, and an ocean of the underworld below (compare [[Rasā]], [[Varuna]]). == See also == <div style="-moz-column-count:4; column-count:4;"> * [[Arctic Ocean]] * [[Atlantic Ocean]] * [[Earthdive]] * [[Indian Ocean]] * [[International Maritime Organization]] * [[Law of the Sea]] * [[Marginal sea]] * [[Marine biology]] * [[Marine debris]] * [[Mediterranean sea]] * [[Ocean acidification]] * [[Oceanography]] * [[Pacific Ocean]] * [[Pelagic zone]] * [[Sea]] * [[Sea level]] and [[sea level rise]] * [[Sea salt]] * [[Sea state]] * [[Seven Seas]] * [[Southern Ocean]] * [[Water]] * [[World Ocean Day]] </div> ==References== <references/> * Matthias Tomczak and J. Stuart Godfrey. 2003. ''Regional Oceanography: an Introduction''. (see [http://www.es.flinders.edu.au/~mattom/regoc/ the site]) * "[http://www.oceansatlas.com/unatlas/about/howoceanswereformed2/originsofoceans/originofocean2jte.html Origins of the oceans and continents]". ''[http://www.oceansatlas.com/ UN Atlas of the Oceans].'' ==External links== {{External links}} {{wiktionary}} * [http://www.oceanexplorer.noaa.gov/ Ocean Explorer] - An educational and reference resource from NOAA * [http://www.whoi.edu/imageOfDay.do Oceanography Image of the Day] - from the [[Woods Hole Oceanographic Institution]] * [http://oceanmotion.org/ Ocean Motion] - Educational reference and data resource from NASA * [http://nosdataexplorer.noaa.gov/nosdataexplorer/ NOS Data Explorer] - A portal to obtain NOAA National Ocean Service data * [http://news.bbc.co.uk/2/hi/science/nature/4033555.stm Science taps into ocean secrets] * [http://www.palomar.edu/oceanography/salty_ocean.htm Why is the ocean salty?] * [http://ioc.unesco.org/ Intergovernmental Oceanographic Commission] * [http://oceana.org Oceana - Protecting the World's Oceans] * [http://www.coreocean.org/ CORE - Consortium for Oceanographic Research and Education] * [http://www.nopp.org/ NOPP - National Oceanographic Partnership Program] * [http://www.nosb.org/ NOSB - National Ocean Sciences Bowl] * [http://www.coml.org/ CoML - Census of Marine Life] * [http://www.thew2o.net World Ocean Observatory] * [http://oceans.greenpeace.org Greenpeace Defending our Oceans] * [http://www.motherjones.com/news/featurex/2006/03/oceans_index.html The Last Days of the Ocean, a ''Mother Jones'' special report on the state of the ocean] * [http://www.theoceanproject.org The Ocean Project] * [http://www.oceanvoyager.org Ocean Voyager], a five-part journey to save the seas, created by ''Mother Jones'' magazine * [http://www.oceanconservancy.org/ The Ocean Conservancy] - Advocates for Wild, Healthy Oceans * [http://dapper.pmel.noaa.gov/dchart NOAA DChart ] - Plot and download ocean data from your browser or Google Earth * [http://www.oceansatlas.org/ UN Atlas of the Oceans] * [http://www.fisheries.org/afs/ American Fisheries Society] * [http://www.cousteau.org/en/ Cousteau Society] * [http://www.meriresearch.org/ Marine Environmental Research Institute] * [http://www.nmfs.noaa.gov/ NOAA National Fisheries] * [http://www.oceanservice.noaa.gov/ NOAA National Ocean Service] * [http://www.oceanalliance.org/ Ocean Alliance] * [http://www.oceanfutures.org/ Ocean Futures Society] * [http://www.ocean.us/ National Office for Integrated and Sustained Ocean Observations] * [http://www.onefish.org/global/index.jsp One Fish] * [http://www.blueocean.org/ Blue Ocean Institute] * [http://www.seastheday.org ''Seas the Day''] * [http://www.sfu.ca/coastalstudies/changingcurrents.htm Changing Currents: Charting a Course of Action for the Future of Oceans] *[http://www.lpi.usra.edu/publications/slidesets/oceans/index.shtml Shuttle Views the Earth: Oceans from Space] * [http://www.worldoceanday.org World Ocean Day - Celebrate our World's Ocean!] [[Category:Oceans| ]] [[Category:Oceanography|Oceans]] [[Category:Greek loanwords]] [[ar:محيط (جغرافيا)]] [[an:Ozián]] [[arc:ܐܘܩܝܢܘܣ]] [[az:Okean]] [[bn:মহাসমুদ্র]] [[zh-min-nan:Hái-iûⁿ]] [[be:Акіян]] [[be-x-old:Акіян]] [[bcl:Kadagatan]] [[bs:Okean]] [[br:Meurvor]] [[bg:Световен океан]] [[ca:Oceà]] [[cv:Океан]] [[cs:Oceán]] [[cy:Cefnfor]] [[da:Verdenshave]] [[de:Ozean]] [[et:Ookean]] [[el:Ωκεανός]] [[es:Océano]] [[eo:Oceano]] [[eu:Ozeano]] [[fa:اقیانوس]] [[fr:Océan]] [[fy:Oseaan]] [[fur:Ocean]] [[gl:Océano]] [[zh-classical:洋]] [[ko:대양]] [[hy:Օվկիանոս]] [[hi:महासागर]] [[hr:Ocean]] [[io:Oceano]] [[ig:Oke osimiri]] [[id:Samudra]] [[is:Sjór]] [[it:Oceano]] [[he:אוקיינוס]] [[jv:Samodra]] [[ka:ოკეანე]] [[sw:Bahari]] [[ht:Oseyan]] [[lo:ມະຫາສະໝຸດ]] [[la:Oceanus]] [[lv:Okeāns]] [[lt:Vandenynas]] [[jbo:braxamsi]] [[hu:Óceán]] [[mk:Океан]] [[mg:Ranomasina]] [[ml:സമുദ്രം]] [[mr:महासागर]] [[ms:Lautan]] [[mn:Далай]] [[nl:Oceaan]] [[ja:大洋]] [[no:Hav#Verdenshavene]] [[nn:Verdshav]] [[uz:Okean]] [[nds:Ozean]] [[pl:Ocean]] [[pt:Oceano]] [[ro:Ocean]] [[qu:Mama qucha]] [[ru:Океан]] [[sq:Oqeani]] [[scn:Ocèanu]] [[simple:Ocean]] [[sl:Ocean]] [[sr:Океан]] [[sh:Ocean]] [[su:Jaladri]] [[fi:Meri]] [[sv:Hav#V.C3.A4rldshav]] [[tl:Karagatan]] [[te:మహాసముద్రము]] [[th:มหาสมุทร]] [[vi:Đại dương]] [[tg:Уқёнус]] [[tr:Okyanus]] [[uk:Океан]] [[ur:سمندر]] [[vec:Oceano]] [[wa:Oceyan]] [[wo:Mbàmbulaan]] [[yi:אקעאן]] [[yo:Òkun]] [[zh-yue:海洋]] [[zh:海洋]]