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Marine biology
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Marine biology

Marine biology is the study of animal and plant life within saltwater ecosystems. 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 deals with those species in which life is spent only (or mainly) in the water, thus its classification is based on the environment rather than on taxonomy.

Table of contents
1 Overview
2 Subfields of marine biology
3 Lifeforms studied in marine biology
4 Reefs
5 Deep sea and trenches
6 How oceanic factors affect distribution of various organisms
7 History of marine biology
8 Institutions, well-known journals


Marine biology covers a great deal, from the microscopic plankton (with phytoplankton hugely important as the primary producers of the sea), to the huge cetaceans (or whale).

A large (exactly how large is unknown at this point) preportion of all life on earth is contained in the oceans. Including many species that are economically important to humans, including the food fishes. It is also becoming understood that the well being of marine organisms and non ocean dwelling organisms is linked in some very fundamental ways.

Subfields of marine biology

The study of marine biology obviously reserves a great deal of attention for the physical effects of continual immersion in sea water and the ocean in general, as well as for the ways that various changing oceanic properties affect marine life. Not being our realm, scientists study how various organisms have adapted to this salty environment.

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

Related fields

Marine biology is closely linked to both oceanography and biology. It also encompasses ideas from ecology. Fisheries science can be considered a partial offshoot of marine biology, as can marine conservation.

Lifeforms studied in marine biology

Microscopic life

Plant life

Other sea life

Cnidarias such as Jellyfish and sea anemone, Ctenophoras, sea worms including phylums: Plathyhelminthes, Nemertea, Annelida, Sipuncula, Echiura, and the Phoronidas; Mollusca including shellfish and squid and octopus, Crustaceans, Poriferas including sponges, Bryozoa, Echinoderms including starfish, Urochordata - sea squirts or tunicates.


Main article: Fish

Fishes inhabit the largest, (by volume) biome on planet earth and since they exist in a watery enviroment it means that very different biological functions have evolved. Fish anatomy includes two chamber heart, operculem, secretory cells that produce mucous, swim bladder, scales, fins, gills, lips and eyes. Fish breathe under water by extracting oxygen from sea water through their gills. Fins are used to propel and stabilize them in their watery environment.

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


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 at 10,924 m (35,838 ft). Water pressure at these depths is extreme and there is no light from above, but some life still exists here. Small flounder Soleidae fish and shrimp were seen by the american crew of the Bathyscaphe Trieste when it dived to the bottom in 1960.

Other notable deeps include Monterey Canyon, in the eastern Pacific, the Tonga Trench in the south west at 32,000 feet, the Philippine trench, the Puerto Rico Trench at 8,605 m (28,232 ft), the Romanche Trench at -7,760 m (24,450 ft), Fram Basin in the Arctic at -4,665 m, the Java Trench at 7,450 m (24,442 ft), and the South Sandwich Trench at -7,235 m.

In general the deep sea is considered to start at the photic zone, the point where sunlight looses 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 around seamounts that rise from the deeps. Fish and other sea life use these as congregating areas, for spawning, and feeding.

Hydrothermal vents in the ocean floor act as oasis's for life. As well as their opposites, cold seeps. These places support unique biomes and many new microbes have been discovered at these places.

How oceanic factors affect distribution of various organisms

An active research topic in marine biology, is discovering and mapping the life cycless of various species and where they spend their time. How the ocean currents affect them. And the effect of the multitudes of other oceanic factors on their growth and well being. This has only recently become technically feasible with the support of GPS and newer underwater visual devices.

Most ocean life and fish breed in specific places, nest or not in others, spend their time as juveniles in still others, and in maturity in yet others. Scientists were at a loss for quite a while as to the location of many species during different parts of their life cycles. In fact where sea turtles travel is still largely unknown. Tracking devices just don't work for some life forms, and the rigors of the ocean are not friendly to technology. But these factors are being overcome in many instances.

History of marine biology

In recent times, marine biologists are trying to complete the mapping of underwater species with the help of modern techniques, which could help in exploring the deepest oceanic depressions in which it is supposed that new species could be found, eventually of potential great interest also for the theories on evolution.

Institutions, well-known journals

Many universities teach courses in marine biology.

General subfields within biology
Anatomy | Bioinformatics | Botany | Ecology | Evolutionary biology | Genetics | Marine biology | Human biology | Cell biology | Microbiology | Molecular biology | Biochemistry | Origin of life | Paleontology | Physiology | Taxonomy | Xenobiology | Zoology