Marine biology
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Marine life can be very abundant. |
Marine biology is the scientific study of the
plants,
animals and other organisms that live in the
ocean. 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.
There are many practical reasons to study marine biology. 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 much of the
oxygen we breathe 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.
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Underwater life differs greatly from land life. |
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 proportion of all life on
Earth exists in the oceans. Exactly how large the proportion is 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), of air (such as
Earth's respiration, and movement of energy through ecosystems. Large areas beneath the ocean surface still remain effectively unexplored.)
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 affects 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 closely linked to both
oceanography and
biology. It also encompasses ideas from
ecology.
Fisheries science and
marine conservation can be considered partial offshoots of marine biology.
Microscopic life
Microscopic life undersea is incredibly varied 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,
crysomonads,
chloromonads,
prasinomonads, 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).
Plant life
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 commonally 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.
Other marine invertebrates
Other 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
Fishes inhabit the largest (by volume)
biome on Earth. They 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.
Marine mammals
There are five main types of marine mammals.
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Cetaceans include
toothed whales (Suborder
Odontoceti), such as the
Sperm Whale,
dolphins, and
porpoises. Cetaceans also include
baleen whales (Suborder
Mysticeti), such as
Gray Whales,
Humpback Whales, Dall's porpoise, and
Blue Whales.
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Sirenians include
manatees, the
Dugong, and the extinct
Steller's Sea Cow.
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Seals (Family
Phocidae),
sea lions (Family
Otariidae - which also include the fur seals), and the Walrus (Family
Odobenidae) are all considered
pinnipeds.
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Sea Otters are members of the Family
Mustelidae, which includes
weasels and
badgers.
* Finally,
Polar Bears (Family
Ursidae) are sometimes considered marine mammals because of their dependence on the sea.
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.
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
photic 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 in the ocean floor act as
oases, as do their opposites,
cold seeps. Such places support unique
biomes and many new
microbes have been discovered at these sights.
Marine biologists are trying to amass a more complete mapping of underwater species with the help of modern techniques. The deepest oceanic depressions are supposed to contain unknown species, possibly also of great potential interest for the theories on
evolution.
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. But these factors are being overcome in many instances.
* Rosie Alling (1992- )- Marine researcher and atmospheric-oceanic journalist
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Jacques-Yves Cousteau, co-inventer of the aqua-lung, is well known for popularizing marine biology. |
* Jakob Johan
Adolf Appellöf (
1857-
1921),
Swedish marine zoologist.
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Joseph Ayers, marine neurophysiologist and biomimetic researcher.
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Samuel Stillman Berry (
1887-
1984), U.S. marine zoologist.
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Henry Bryant Bigelow (1879-1967), U.S. marine biologist.
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Rachel Carson (
1907-
1964) American Marine Biologist and Author.
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Carl Chun (
1852-
1914),
German marine biologist
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Jacques-Yves Cousteau (
1910-
1997),
French marine biologist and explorer.
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Anton Dohrn (
1840-
1909), German marine biologist.
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Sylvia Earle (born
1935), American oceanographer.
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Johan Hjort, Norwegian marine zoologist and one of the founders of
ICES.
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Bruno Hofer (
1861-
1916), German fisheries scientist.
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Hirohito, Japanese emperor.
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August David Krohn (
1803â€"
1891), Russian/German zoologist.
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William Elford Leach (
1790-
1836),
English zoologist and marine biologist.
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Philip S. Lobel Professor,
Boston University Marine Program
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Nicholai Miklukho-Maklai (
1846-
1888),
Russian marine biologist and anthropologist.
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Sir John Murray (
1841-
1914),
Scots-
Canadian marine biologist.
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Harald Rosenthal (born
1937), German hydrobiologist known for his work in fish farming and ecology.
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Michael Sars (1809-1869),
Norwegian theologian and biologist.
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Georg Sars (
1837-
1927), Norwegian marine biologist.
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Ruth Turner (
1915-
2000), marine biologist.
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Robert Paine Professor, emeritus
University of Washington intertidal Ecologist
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Charles Wyville Thompson (
1832-
1882), Scottish marine biologist
Source:
List of biologists.
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Animal*
Biology*
Fish*
Important publications in marine biology*
The Marine Mammal Center*
Ocean*
Plant*
Sea*
Mammals*
Oceanography Image of the Day , from the Woods Hole Oceanographic Institution
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MarineBio: an evolving online tribute to Marine Biology and all Ocean life.*
Marine Conservation Society: UK charity for seas and wildlife.*
SeaTurtle.org: Tracking a sea turtle.*
Marinebiology.co.uk a marine biology resource.*
Marine Ecology Progress Series (MEPS).*
Marine Biological Association of the United Kingdom.*
Marine Life Information Network for Britain and Ireland - MarLIN.*
Freshwater and Marine Image Bank The Freshwater and Marine Image Bank is an ongoing digital collection of images related to freshwater and marine topics. From the University of Washington Libraries Digital Images Collection
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PISCO - Partnership for Interdisciplinary Studies of Coastal Oceans
