Portal:Marine life

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Marine life

General characteristics of a large marine ecosystem (Gulf of Alaska)

Marine life, or sea life or ocean life, is the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life helps determine the very nature of our planet. Marine organisms produce much of the oxygen we breathe. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land.

Most life forms evolved initially in marine habitats. Oceans provide about 99 percent of the living space on the planet. The earliest vertebrates appeared in the form of fish, which live exclusively in water. Some of these evolved into amphibians which spend portions of their lives in water and portions on land. Other fish evolved into land mammals and subsequently returned to the ocean as seals, dolphins or whales. Plant forms such as kelp and algae grow in the water and are the basis for some underwater ecosystems. Plankton, and particularly phytoplankton, are key primary producers forming the general foundation of the ocean food chain.

Marine vertebrates must obtain oxygen to survive, and they do so in various ways. Fish have gills instead of lungs, although some species of fish, such as the lungfish, have both. Marine mammals, such as dolphins, whales, otters, and seals need to surface periodically to breathe air. Some amphibians are able to absorb oxygen through their skin. Invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters including breathing tubes (see insect and mollusc siphons) and gills (Carcinus). However, as invertebrate life evolved in an aquatic habitat most have little or no specialisation for respiration in water.

Altogether there are 230,000 documented marine species, including about 20,000 species of fish, and it has been estimated that nearly two million marine species are yet to be documented. Marine species range in size from the microscopic, including plankton and phytoplankton which can be as small as 0.02 micrometres, to huge cetaceans (whales, dolphins and porpoises) which in the case of the blue whale reach up to 33 metres (109 feet) in length, being the largest known animal.

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Oceanic Whitetip Shark.png

The oceanic whitetip shark, Carcharhinus longimanus, is a large pelagic shark of tropical and warm temperate seas. It is a stocky shark, most notable for its long, white tipped rounded fins.

This aggressive but slow-moving fish dominates feeding frenzies, and has attacked more humans than all other shark species combined — it is a notable danger to survivors of oceanic ship wrecks and downed aircraft. Recent studies have shown that its numbers are in steep decline — its large fins are highly valued as the chief ingredient of shark fin soup and, as with other shark species, the oceanic whitetip faces mounting pressure from fishing throughout its range.

The oceanic whitetip shark was first described by naturalist René Lesson in his account of observations made during Louis Duperrey's 1822–1825 circumnavigation of the world on the corvette Coquille. Lesson described two specimens found in the Tuamotu Archipelago in French Polynesia, and named the shark Squalus maou after a Polynesian word for "shark". However, Lesson's description and name were forgotten.

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Jacques-Yves Cousteau in 1976.

Jacques-Yves Cousteau (11 June 1910 – 25 June 1997) was a French naval officer, explorer, ecologist, filmmaker, photographer and researcher who studied the sea and all forms of life in water. He co-developed the aqua-lung, pioneered marine conservation and was a member of the Académie française.

Cousteau was born in Saint André de Cubzac, France to Daniel and Elizabeth Cousteau on June 11, 1910 and died in Paris, France. He is generally known in France as le commandant Cousteau ("Commander Cousteau"). Worldwide, he was commonly known as Jacques Cousteau or Captain Cousteau.

Cousteau liked to call himself an "oceanographic technician". He was in reality a sophisticated lover of nature. His work permitted many people to explore the resources of the "blue continent".

His work also created a new kind of scientific communication, criticised at the time by some academics. The so-called divulgationisme, a simple way of sharing scientific concepts, was soon employed in other disciplines and became one of the most important characteristics of modern TV broadcasting.

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Light microscopy image of the undescribed species of Spinoloricus that is living in anoxic environment (Stained with Rose Bengal). Scale bar is 50 μm.
Titan triggerfish.jpg
  • Triggerfishes are the brightly coloured fishes of the family Balistidae. (pictured)
  • The sea otter often keeps a stone tool in its armpit pouch.

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Electron microscope image of the compound eye -  the eyes are deep black in the living animal
Photo credit: Gerd Alberti and Uwe Kils

The Antarctic krill (Euphausia superba) is a species of krill found in the Antarctic waters of the Southern Ocean. Antarctic krill are shrimp-like invertebrates that live in large schools, called swarms, sometimes reaching densities of 10,000 - 30,000 individual animals per cubic meter.

Although the uses for and reasons behind the development of their massive black compound eyes (pictured above) remain a mystery, there is no doubt that Antarctic krill have one of the most fantastic structures for vision seen in nature.

Krill can shrink in size from one molt to the next, which is generally thought to be a survival strategy to adapt to scarce food supplies (a smaller body needs less energy, i.e., food). However, the animal's eyes do not shrink when this happens. The ratio between eye size and body length has thus been found to be a reliable indicator of starvation.

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Marine Life Categories

Major Fields of Marine Biology: Marine Biology - Ecology - Zoology - Animal Taxonomy

Specific Fields of Marine Biology: Herpetology - Ichthyology - Planktology - Ornithology

Biologists: Zoologists - Algologists - Malacologists - Conchologists - Biologists - Marine Biologists - Anatomists - Botanists - Ecologists - Ichthyologists

Organisms:

Plants: Algae - Brown Algae - Green Algae - Red Algae - Sea Vegetables -

Invertebrates: Cnidarians - Echinoderms - Molluscs - Bivalves - Cephalopods - Gastropods

Fish: Fish - Bony fish - Lobe-finned fish - Ray-finned fish - Cartilaginous fish - Electric fish - Fish diseases - Rays - Sharks - Extinct fish - Fictional fish - Fisheries science - Fishing - Fishkeeping - Live-bearing fish

Reptiles and Amphibians: Marine reptiles - Sea turtles - Mosasaurs - Sauropterygia

Mammals: Marine mammals - Cetaceans - Pinnipeds - Sirenians

Miscellaneous: Aquaria - Oceanaria - Agnatha - Endangered species - Aquatic biomes - Ecozones - Aquatic organisms - Cyanobacteria - Dinoflaggellates

Marine Life Topics

Ocean zones: Photic zoneAphotic zonePelagic zoneNeritic zoneLittoral zoneSublittoral zoneBenthic zone
Plants and Algae: AlgaeBrown algaeRed algaeGreen algaeSeagrassPhytoplankton
Invertebrates: SquidCuttlefishCrabsLobstersStarfish Cscr-featured.svgSea UrchinJellyfishPortuguese man o' warCorals Symbol support vote.svgTunicates Symbol support vote.svg
Fish: LampreysJawless fishCartilagenous fishBony fishSharksRaysSkatesCoelacanthsLungfishPlacodermiLobe-finned fishRay-finned fishSturgeonsGarsEelsHerringsSalmonTroutLancetfishAnglerfishToadfishCodsFlyingfishSeahorsesFlatfishScorpionfishCichlids
Reptiles: CrocodilesAlligatorsCaimanGharialTurtlesSea turtlesLeatherback turtleMarine iguanaSea snakes Symbol support vote.svg
Birds: PenguinsSea gullsKittiwakesAlbatrosses Cscr-featured.svgSea ducksCormorantsSea eagleGuillemotsPuffinsAuksTernsGannetsOsprey Symbol support vote.svgRazorbillOystercatchers
Mammals: MonotremesMarsupialsCetaceansWhalesDolphinsPorpoisesPinnipedsWalruses Symbol support vote.svgTrue sealsFur sealsSea LionsSireniansManateesDugongs Symbol support vote.svgPolar bear Symbol support vote.svgSea otter Cscr-featured.svgMarine otterBlubber
Cscr-featured.svg Represents a Featured article, Symbol support vote.svg Represents a Good article


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