marine biology

(redirected from Marine life)
Also found in: Dictionary, Wikipedia.

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.
..... Click the link for more information.
, 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.
..... Click the link for more information.
, 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.
..... Click the link for more information.
. 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.
..... Click the link for more information.
, 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.
..... Click the link for more information.
, 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.
..... Click the link for more information.
), 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
..... Click the link for more information.
 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.
..... Click the link for more information.
), 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.
..... Click the link for more information.
 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
..... Click the link for more information.
). 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
..... Click the link for more information.
, 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.
..... Click the link for more information.
. 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.
..... Click the link for more information.
 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.
..... Click the link for more information.
). 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.
..... Click the link for more information.
 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.
..... Click the link for more information.
; 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.
..... Click the link for more information.
 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
..... Click the link for more information.
 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
..... Click the link for more information.
.

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 ?
It is widely believed that replacing the impulsive air gun sources with controlled marine vibratory sources would greatly reduce the harm to marine life, yet to date, no suitable air gun replacement has been identified and widely adopted by the industry.
The bay once served as a rich source of food for marine life, but when busy shipping routes developed in and out of Liverpool, the wildlife was forced to leave the safety of the bay as the water became dirty and the food supply dwindled.
The aquarium has released other marine life before, including seahorses in 2014 and turtles previously.
Major hazards to the marine life are pollution, over exploitation and different wastage of fuel.
ETAP said Zenobia has become an exceptional artificial reef, hosting thousands of species of fish and other marine life and that was why the competition seeks to record this impressive world and present it to the wider public.
KU), has signed a 10-year bancassurance agreement with Tokio Marine Life Insurance Malaysia Berhad, effective January 1, The WSJ has reported.
The project will also help in fostering and protecting endangered marine life organisms such as turtles and boost biological diversity of the local marine life.
656 of 2014, regulating fishing using nets aimed at preserving marine life and supporting the fishing industry.
SIDON, Lebanon: With the long-term project to turn Sidon's notorious dumpsite into a proper landfill completed in early July, a new report has praised the recently constructed seawall for having stimulated the re-emergence of marine life.
DRINKERS at a coastal pub will this year be helping marine life in the North Sea.
1 ( ANI ): A new study used advanced climate models to predict that seafloor dwelling marine life would decline by 38 per cent in the North Atlantic and over five per cent globally over the next century.
A final, more text-heavy chapter addresses conservation of tropical marine life.

Full browser ?