marine biology

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marine biology,

study of ocean plants and animals and their ecological relationships. Marine organisms may be classified (according to their mode of life) as nektonic, planktonic, or benthic. Nektonic animals are those that swim and migrate freely, e.g., adult fishesfish,
limbless aquatic vertebrate animal with fins and internal gills. Traditionally the living fish have been divided into three class: the primitive jawless fishes, or Agnatha; the cartilaginous (sharklike) fishes, or Chondrichthyes; and the bony fishes, or Osteichthyes.
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, whaleswhale,
aquatic mammal of the order Cetacea, found in all oceans of the world. Members of this order vary greatly in size and include the largest animals that have ever lived. Cetaceans never leave the water, even to give birth.
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, and squidsquid,
carnivorous marine cephalopod mollusk. The squid is one of the most highly developed invertebrates, well adapted to its active, predatory life. The characteristic molluscan shell is reduced to a horny plate shaped like a quill pen and buried under the mantle.
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. Planktonic organisms, usually very small or microscopic, have little or no power of locomotion and merely drift or float in the water. Benthic organisms live on the sea bottom and include sessile forms (e.g., spongessponge,
common name for members of the aquatic animal phylum Porifera, and for the dried, processed skeletons of certain species used to hold water. Over 4,500 living species are known; they are found throughout the world, especially in shallow temperate waters.
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, oystersoyster,
bivalve mollusk found in beds in shallow, warm waters of all oceans. The shell is made up of two valves, the upper one flat and the lower convex, with variable outlines and a rough outer surface.
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, and coralscoral,
small, sedentary marine animal, related to the sea anemone but characterized by a skeleton of horny or calcareous material. The skeleton itself is also called coral.
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), creeping organisms (e.g., crabscrab,
crustacean with an enlarged cephalothorax covered by a broad, flat shell called the carapace. Extending from the cephalothorax are the various appendages: five pairs of legs, the first pair bearing claws (or pincers), are attached at the sides; two eyes on short, movable
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 and snailssnail,
name commonly used for a gastropod mollusk with a shell. Included in the thousands of species are terrestrial, freshwater, and marine forms. Some eat both plant and animal matter; others eat only one type of food.
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), and burrowing animals (e.g., many clamsclam,
common name for certain bivalve mollusks, especially for marine species that live buried in mud or sand and have valves (the two pieces of the shell) of equal size.
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 and wormsworm,
common name for various unrelated invertebrate animals with soft, often long and slender bodies. Members of the phylum Platyhelminthes, or the flatworms, are the most primitive; they are generally small and flat-bodied and include the free-living planarians (of the class
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). Seafloor areas called hydrothermal ventshydrothermal vent,
crack along a rift or ridge in the deep ocean floor that spews out water heated to high temperatures by the magma under the earth's crust. Some vents are in areas of seafloor spreading, and in some locations water temperatures above 350°C; (660°F;) have
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, with giant tube worms and many other unusual life forms, have been intensively studied by marine biologists in recent years.

The distribution of marine organisms depends on the chemical and physical properties of seawater (temperature, salinity, and dissolved nutrients), on ocean currents (which carry oxygen to subsurface waters and disperse nutrients, wastes, spores, eggs, larvae, and plankton), and on penetration of light. Photosynthetic organisms (plants, algae, and cyanobacteria), the primary sources of food, exist only in the photic, or euphotic, zone (to a depth of about 300 ft/90 m), where light is sufficient for photosynthesisphotosynthesis
, process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the presence of chlorophyll. Some of the plants that lack chlorophyll, e.g.
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. Since only about 2% of the ocean floor lies in the photic zone, photosynthetic organisms in the benthos are far less abundant than photosynthetic plankton (phytoplankton), which is distributed near the surface oceanwide. Very abundant phytoplankton include the diatomsdiatom
, unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although some join to form colonies.
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 and dinoflagellates (see Dinoflagellatadinoflagellata
, phylum (division) of unicellular, mostly marine algae, called dinoflagellates. In some classification systems this division is called Pyrrhophyta. There are approximately 2,000 species of dinoflagellates.
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). Heterotrophic plankton (zooplankton) include such protozoansprotozoan
, informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues.
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 as the foraminiferansforaminiferan
, common name for members of the class Foraminifera, large, shelled ameboid protozoans belonging to the phylum Sarcodina. Most foraminiferan shells are calcareous, but some are siliceous, and others are built of sand grains.
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; they are found at all depths but are more numerous near the surface. Bacteriabacteria
[pl. of bacterium], microscopic unicellular prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles. Once considered a part of the plant kingdom, bacteria were eventually placed in a separate kingdom, Monera.
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 are abundant in upper waters and in bottom deposits.

The scientific study of marine biology dates from the early 19th cent. and now includes laboratory study of organisms for their usefulness to humans and the effects of human activity on marine environments. Important marine biological laboratories include those at Naples, Italy; at Plymouth and Millport in England; and at Woods Hole, Mass., La Jolla, Calif., and Coral Gables, Fla. Research has been furthered by unmanned and manned craft, such as the submersiblesubmersible,
small, mobile undersea research vessel capable of functioning in the ocean depths. Development of a great variety of submersibles during the later 1950s and 1960s came about as a result of improved technology and in response to a demonstrated need for the capability
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 Alvin.

See also oceanographyoceanography,
study of the seas and oceans. The major divisions of oceanography include the geological study of the ocean floor (see plate tectonics) and features; physical oceanography, which is concerned with the physical attributes of the ocean water, such as currents and
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.

Bibliography

See R. Carson, The Sea Around Us (rev. ed. 1961); R. Ballard, Exploring Our Living Planet (1983); M. Banks, Ocean Wildlife (1989); W. J. Broad, The Universe Below (1997).

marine biology

[mə′rēn bī′äl·ə·jē]
(biology)
A branch of biology that deals with those living organisms which inhabit the sea.
References in periodicals archive ?
com)-- This summer, Coco Palm Dhuni Kolhu is host to a group of Marine Biologists from the Manta Trust who will be spending 2 days at the resort, engaging guests in interactive presentations and inviting them to join a spectacular snorkeling excursion in South Baa Atoll, where they hope to encounter some Manta Rays gliding through the deep blue.
PHOENIX, July 26 /PRNewswire/ -- Marine biologist David Caldwell and the Highland Council have agreed to a plan that will finally track and capture the large predatory creature that inhabits Scotland's famous lake.
Marine biologists at the Bournemouth-based centre came up with the idea of croaking to their camouflaging tree frogs when they had trouble finding the colour-changing creatures.
I spent Christmas night with a marine biologist, watching a leatherback turtle the size of a golf cart lay her clutch of eggs.
There is an on-site naturalist and marine biologist, as well as offerings of scuba diving and hiking.
District Magistrate Thomas Coffin in Eugene was correct to allow expert testimony on behalf of Clausen Oysters from marine biologist Ralph Elston, who concluded by a process of elimination that low concentrations of oil spilled by the ship were responsible for the deaths of the oysters.
A WIRRAL schoolgirl is following her dream to become a marine biologist thanks to a new bursary scheme.
Marine biologist Dr Kevin Robinson wants Government funding.
Hypoxia in the Gulf of Mexico exists in a larger ecological context, says Len Bahr, a marine biologist who is coastal advisor to Louisiana governor Mike Foster.
His lyrical approach to science enraptured his Surrealist contemporaries, hut Painleve was no common egghead; he raced cars professionally, participated in the Resistance, played poker with the Surrealists, enjoyed the tribulations of a field-working marine biologist, and even got to direct Artaud.
As a cameraman records a marine biologist conducting onboard research vessel demonstrations, the VBrick appliance feeds the live, compressed video signal to an onboard radio transmitter that includes omni-directional antennas.
Aberdulais-based marine biologist Judith Oakley is among those organising events to help identify the species breeding grounds.

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