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Sci-Tech Dictionary:

marine biology

(mə′rēn bī′äl·ə·jē)

(biology) A branch of biology that deals with those living organisms which inhabit the sea.

 
 
Britannica Concise Encyclopedia: marine biology

Science that deals with the animals and plants of the sea and estuaries and with airborne and terrestrial organisms that depend directly on bodies of saltwater for food and other necessities. Marine biologists study the relations between ocean phenomena and the distribution and adaptations of organisms. Of particular interest are adaptations to the chemical and physical properties of seawater, the movements and currents of the ocean, the availability of light at various depths, and the composition of the sea floor. Other important areas of study are marine food chains, the distribution of economically important fish and crustaceans, and the effects of pollution. In the later 19th century, the emphasis was on collecting and cataloging marine organisms, for which special nets, dredges, and trawls were developed. In the 20th century, improved diving equipment, submersible craft, and underwater cameras and television have made direct observation possible.

For more information on marine biology, visit Britannica.com.

 
US History Encyclopedia: Marine Biology

Study of life along the seashore, which became known as marine biology by the twentieth century, was first developed and institutionalized in the United States at the end of the nineteenth century. Two distinct traditions contributed to its modern disciplinary form.

First to emerge was marine biology as a summertime educational activity, chiefly designed to instruct teachers of natural history about how to study nature within a natural setting. The notion was first suggested to Louis Agassiz, the Harvard zoologist and geologist, by his student Nathaniel Southgate Shaler. Shaler had conducted highly successful summer field experiences for geology students, and felt that similar experiences could be valuable for biology students. Encouraged by his wife, Elizabeth—a longtime advocate for educational opportunities for the largely female teaching community—Agassiz obtained funding and opened the Anderson School of Natural History in 1873 on Penikese Island, located not too distant from Cape Cod. Following this school, several others offered similar experiences. The Summer School of the Peabody Academy of Sciences (Salem, Massachusetts) sponsored instruction for teachers in marine botany and zoology in 1876, and the Boston Society of natural History, with the support of the Women's Education Association (WEA) of Boston, started its summer station north of Boston at Alpheus Hyatt's vacation home in Annisquam.

The second tradition was European, where several marine stations operated by 1880, most notably the Stazione Zoologica in Naples. This marine biology laboratory was founded by Anton Dohrn in 1872. The "Mecca for marine biology," as Naples was soon known, attracted scholars from throughout the world. Agassiz's son, Alexander Agassiz, imported Dohrn's notion to his summer home near Newport, Rhode Island, offering the latest microscopical tools for researchers. William Keith Brooks, a student of the elder Agassiz, accepted the invitation and completed his doctoral research with the younger Agassiz in 1875. Then, when Brooks obtained a position at America's first graduate university, Johns Hopkins University, one of his first tasks was to create a research laboratory in marine biology. Thus, the Chesapeake Zoological Laboratory was opened in 1878

The first U.S. marine biology laboratory to incorporate both traditions was the Marine Biological Laboratory (MBL), which opened in Woods Hole, Massachusetts, in 1888. It originally offered courses in marine botany and marine zoology for beginning students and teachers. But its original director, C. O. Whitman, had spent time at Naples and, like his colleague Brooks, wanted to create research opportunities in marine biology for more advanced students and researchers. To accomplish the task, Whitman initiated advanced courses in embryology, invertebrate zoology, cytology, and microscopy, all of which began to attract more sophisticated students. By the early twentieth century, the MBL welcomed only advanced students and investigators.

Similar marine biology Laboratories were founded on the Pacific Coast. Stanford University established the Hopkins Marine Station in Pacific Grove, California, in 1892. To the north, the University of Washingt on opened a marine station near Friday Harbor (San Juan Islands, Washington) in 1904. Henry Chandler Cowles, an ecologist from the University of Chicago who had done pioneering studies on the sand dunes of Lake Michigan started a course in intertidal ecology, the first such course in the United States.

One additional West Coast laboratory played a critical role in defining the new field of marine biology, albeit by exclusion. William Emerson Ritter, an embryologist from Berkeley, created a laboratory near San Diego, initially named the San Diego Marine Biological Laboratory, in 1903. But Ritter was interested in a more global approach to investigations by the seashore, an approach he never successfully defined. He was successful, however, in attracting the financial resources of the Scripps family, and soon the Scripps Institution for Biological Research was built north of the village of La Jolla. Ritter specifically stated that he had no intention of forming another MBL on the West Coast, preferring to emphasize a comprehensive study of the sea. After he retired, without creating an educational base for the institution similar to the other stations, he was replaced by Thomas Wayland Vaughan in 1924. The La Jolla station was renamed the Scripps Institution of Oceanography, and marine biology disappeared as a focus.

The three major American marine biology stations throughout the twentieth century and into the twenty-first century are the MBL, Hopkins Marine Station, and Friday Harbor Laboratories. By the end of world War I (1914–1918), the stations defined marine biology as the study of life in the littoral zone (also known as the inter-tidal zone), or the area that serves as an interface between the marine and terrestrial environments. Courses at the laboratories helped to divide marine biology into several specialty areas, including invertebrate zoology, ecology, algology, embryology, and invertebrate physiology. Following World War II (1939–1945), this focus shifted somewhat as more research funding was available in the biological sciences, especially in terms of research questions with an application to medicine and to the exciting field of molecular biology. Woods Hole's MBL, for example, has all but abandoned the traditional areas of marine biology for specialized medical and genetic research. Most investigations at the MBL by the end of the twentieth century were laboratory-based studies of cellular and molecular processes, with little fieldwork or studies of marine life. At the same time, largely because the West Coast has a more robust intertidal fauna and flora that is largely unaffected by human intervention, Hopkins and Friday Harbor retain a traditional focus on marine biology.

For the most part, marine biology does not include investigations of the open seas, studies of freshwater marine systems, or inquiries into the country's fisheries. Biological oceanography, a subdiscipline of Oceanography, examines biological questions in the oceans, including studies of marine mammals, marine fisheries, and freshwater sources for the ocean (limnology).

Bibliography

Benson, Keith R. "Laboratories on the New England Shore: The 'Somewhat Different Direction' of American Marine Biology." New England Quarterly 56 (1988): 53–78.

———. "Summer Camp, Seaside Station, and Marine Laboratory: Marine Biology and Its Institutional Identity." Historical Studies in the Physical and Biological Sciences 32, no. 1 (2001).

Maienschein, Jane. 100 Years Exploring Life, 1888–1988: The Marine Biological Laboratory at Woods Hole. Boston: Jones and Bartlett Publishers, 1989.

 
Columbia Encyclopedia: 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 fishes, whales, and squid. 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., sponges, oysters, and corals), creeping organisms (e.g., crabs and snails), and burrowing animals (e.g., many clams and worms). Seafloor areas called hydrothermal vents, 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 photosynthesis. 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 diatoms and dinoflagellates (see Dinoflagellata). Heterotrophic plankton (zooplankton) include such protozoans as the foraminiferans; they are found at all depths but are more numerous near the surface. Bacteria 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 submersible Alvin.

See also oceanography.

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).

 
Wikipedia: marine biology
Various species of reef fish in the Northwestern Hawaiian Islands.
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Various species of reef fish in the Northwestern Hawaiian Islands.

Marine biology is the scientific study of living organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.

Marine life represents a vast resource, providing food, medicine, and raw materials, in addition to helping to support recreation and tourism all over the world. At a fundamental level, marine life helps determine the very nature of our planet. Marine organisms produce 90% of the oxygen we breathe[citation needed] and probably help regulate the earth's climate. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land.

Underwater life differs greatly from land life (shown: cuttlefish, which have no close terrestrial relatives).
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Underwater life differs greatly from land life (shown: cuttlefish, which have no close terrestrial relatives).

Marine biology covers a great deal, from the microscopic, including plankton and phytoplankton, which can be as small as 0.02 micrometers and are both hugely important as the primary producers of the sea, to the huge cetaceans (whales) which reach up to a reported 33 meters (109 feet) in length.

The habitats studied by marine biology include everything from the tiny layers of surface water in which organisms and abiotic items may be trapped in surface tension between the ocean and atmosphere, to the depths of the abyssal trenches, sometimes 10,000 meters or more beneath the surface of the ocean. It studies habitats such as coral reefs, kelp forests, tidepools, muddy, sandy, and rocky bottoms, and the open ocean (pelagic) zone, where solid objects are rare and the surface of the water is the only visible boundary.

A large amount of all life on Earth exists in the oceans. Exactly how large the proportion is still unknown. While the oceans comprise about 71% of the Earth's surface, due to their depth they encompass about 300 times the habitable volume of the terrestrial habitats on Earth.

Many species are economically important to humans, including the food fishes. It is also becoming understood that the well-being of marine organisms and other organisms are linked in very fundamental ways. Human understanding is growing of the relationship between life in the sea and important cycles such as that of matter (such as the carbon cycle) and of air (such as Earth's respiration, and movement of energy through ecosystems). Large areas beneath the ocean surface still remain effectively unexplored. Scientists know more about the moon than they know about the ocean and the life in it.[citation needed]

Subfields

The marine ecosystem is large, and thus there are many subfields of marine biology. Most involve studying specializations of particular species (i.e., phycology, invertebrate zoology, ichthyology).

Other subfields study the physical effects of continual immersion in sea water and the ocean in general, adaptation to a salty environment, and the effects of changing various oceanic properties on marine life. A subfield of marine biology studies the relationships between oceans and ocean life, and global weather and environmental issues (such as carbon dioxide displacement).

Recent marine biotechnology has focused largely on marine biomolecules, especially proteins, that may have uses in medicine or engineering. Marine environments are the home to many exotic biological materials that may inspire biomimetic materials.

An interesting branch of marine biology is aquaculture; which some countries do a lot of in the oceans, especially Japan.

Related fields

Marine biology is a branch of oceanography and is closely linked to biology. It also encompasses many ideas from ecology. Fisheries science and marine conservation can be considered partial offshoots of marine biology. The most dangerous organisms live in the ocean. And the most dangerous snakes are sea snakes.

Lifeforms

Microscopic life

A copepod.
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A copepod.

Microscopic life undersea is incredibly diverse and still poorly understood. For example, the role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century.

The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae (red, green, brown, and yellow-green), diatoms, dinoflagellates, euglenoids, coccolithophorids, cryptomonads, chrysophytes, chlorophytes, prasinophytes, and silicoflagellates.

Zooplankton tend to be somewhat larger, and not all are microscopic. Many Protozoa are zooplankton, including dinoflagellates, zooflagellates, foraminiferans, and radiolarians. Some of these (such as dinoflaggelates) are also phytoplankton; the plant/animal distinction often breaks down in very small organisms. Other zooplankton include cnidarians, ctenophores, chaetognaths, molluscs, arthropods, urochordates, and annelids such as polychaetes. Many larger animals begin their life as zooplankton before they become large enough to take their familiar forms. Two examples are fish larvae and sea stars (also called starfish).

Plants and algae

Giant kelp.
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Giant kelp.

Plant life is relatively rare undersea. Most of the niche occupied by plants on land is actually occupied by macroscopic algae in the ocean, such as Sargassum and kelp which are commonly known as seaweeds. The non algae plants that do survive in the sea are often found in shallow waters, such as the seagrasses (examples of which are eelgrass, Zostera, and turtlegrass, Thalassia). These plants have adapted to the high salinity of the ocean environment. The intertidal zone is also a good place to find plant life in the sea, where mangroves or cordgrass or beach grass might grow. Sea kelp is very important to small sea creatures because the creatures can hide from predators.

Marine invertebrates

As on land, invertebrates make up a huge portion of all life in the sea. Invertebrate sea life includes Cnidaria such as jellyfish and sea anemone; Ctenophora; sea worms including phyla Plathyhelminthes, Nemertea, Annelida, Sipuncula, Echiura, and the Phoronida; Mollusca including shellfish, squid, octopus; Crustaceans; Porifera including sponges, Bryozoa, Echinodermata including starfish; and Urochordata - sea squirts or tunicates.

Fish

Main article: Fish

Fish have evolved very different biological functions from other large organisms. Fish anatomy includes a two-chambered heart, operculum, secretory cells that produce mucous, swim bladder, scales, fins, lips and eyes. Fish breathe by extracting oxygen from water through their gills. Fins propel and stabilize the fish in the water.

Well known fish include: sardines, anchovy, tuna, clownfish (also known as anemonefish), and bottom fish which include halibut and ling cod. Predators include sharks and barracuda.

Reptiles

Main article: Marine reptile

Reptiles which inhabit or frequent the sea include sea turtles, Marine Iguanas, sea snakes, and saltwater crocodiles. Since all extant marine reptiles are oviparous and need to return to land to lay their eggs, most reptile species live on or near land, rather than in the ocean. Some extinct marine reptiles, such as ichthyosaurs, evolved to be viviparous and had no requirement to return to land.

Seabirds

Seabirds are species of Birds adapted to living in the marine environment, examples including albatross, penguins, gannets, and auks. Although they spend most of their lives in the ocean, species such as gulls can often be found thousands of miles inland.

Marine mammals

Main article: Marine mammal

There are five main types of marine mammals.

Oceanic Habitats

Reefs

Main article: Coral reef

Reefs comprise some of the densest and most diverse habitats in the world. The best-known types of reefs are tropical coral reefs which exist in most tropical waters; however, reefs can also exist in cold water. Reefs are built up by corals and other calcium-depositing animals, usually on top of a rocky outcrop on the ocean floor. Reefs can also grow on other surfaces, which has made it possible to create artificial reefs. Coral reefs also support a huge community of life, including the corals themselves, their symbiotic zooxanthellae, tropical fish and many other organisms.

Much attention in marine biology is focused on coral reefs and the El Niño weather phenomenon. In 1998, coral reefs experienced a "once in a thousand years" bleaching event, in which vast expanses of reefs across the Earth died because sea surface temperatures rose well above normal. Some reefs are recovering, but scientists say that 58% of the world's coral reefs are now endangered and predict that global warming could exacerbate this trend.

Deep sea and trenches

The ocean is deep, very deep in some places. The deepest recorded measure to date is the Mariana Trench, near the Philippines, in the Pacific Ocean at 10924 m (35838 ft). At such depths, water pressure is extreme and there is no sunlight, but some life still exists. Small flounder (family Soleidae) fish and shrimp were seen by the American crew of the bathyscaphe Trieste when it dove to the bottom in 1960.

Other notable oceanic trenches include Monterey Canyon, in the eastern Pacific, the Tonga Trench in the southwest at 10,882 m (35,702 feet), the Philippine Trench, the Puerto Rico Trench at 8605 m (28232 ft), the Romanche Trench at 7760 m (24450 ft), Fram Basin in the Arctic Ocean at 4665 m (15305 ft), the Java Trench at 7450 m (24442 ft), and the South Sandwich Trench at 7235 m (23737 ft).

In general, the deep sea is considered to start at the aphotic zone, the point where sunlight loses its power of transference through the water. Many life forms that live at these depths have the ability to create their own light.

Much life centers on seamounts that rise from the deeps, where fish and other sea life congregate to spawn and feed. Hydrothermal vents along the mid-ocean ridge spreading centers act as oases, as do their opposites, cold seeps. Such places support unique biomes and many new microbes and other lifeforms have been discovered at these locations.

Open ocean

The great expanse of open ocean habitat is huge, and many species can be found passing through it and living in it. The term "open ocean" usually is meant to refer to the vast stretches of water between points of land, or between undersea mounts. Contrary to popular notions the open ocean is often not the place where marine animals spend the majority of their lives. Most species simply pass through the open ocean on their ways to other places. Larger species are the main ongoing inhabitants...

Intertidal and shore

Limpets in the intertidal zone in Cornwall, England.
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Limpets in the intertidal zone in Cornwall, England.

Intertidal zones, those areas close to shore, are constantly being exposed and covered by the ocean's tides. A huge array of life lives within this zone.

Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on the shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion.

How oceanic factors affect distribution of various organisms

An active research topic in marine biology is to discover and map the life cycles of various species and where they spend their time. Marine biologists study how the ocean currents, tides and many other oceanic factors affect ocean lifeforms, including their growth, distribution and well-being. This has only recently become technically feasible with advances in GPS and newer underwater visual devices.

Most ocean life breeds in specific places, nests or not in others, spends time as juveniles in still others, and in maturity in yet others. Scientists know little about where many species spent different parts of their life cycles. For example, it is still largely unknown where sea turtles travel. Tracking devices do not work for some life forms, and the ocean is not friendly to technology.

Famous marine biologists

Jacques-Yves Cousteau, co-inventor of the aqua-lung, is well known for popularizing marine biology.
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Jacques-Yves Cousteau, co-inventor of the aqua-lung, is well known for popularizing marine biology.

Source: List of biologists.

See also

External links

Major subtopics of biology
Anatomy - Astrobiology - Biochemistry - Bioinformatics - Botany - Cell biology - Ecology - Developmental biology - Evolutionary biology - Genetics - Genomics - Marine biology - Human biology - Microbiology - Molecular biology - Origin of life - Paleontology - Parasitology - Pathology - Physiology - Taxonomy - Zoology

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Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
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Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Marine biology".  Read more

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