Marine life, or sea life or ocean life, is the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms produce oxygen and sequester carbon. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land. The term marine comes from the Latin mare, meaning sea or ocean.
Most life forms evolved initially in marine habitats. By volume, oceans provide about 90 percent of the living space on the planet. The earliest vertebrates appeared in the form of fish, which live exclusively in water. Some of these evolved into amphibians which spend portions of their lives in water and portions on land. Other fish evolved into land mammals and subsequently returned to the ocean as seals, dolphins or whales. Plant forms such as kelp and algae grow in the water and are the basis for some underwater ecosystems. Plankton forms the general foundation of the ocean food chain, particularly the phytoplankton which are key primary producers.
Marine invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters, including breathing tubes as in mollusc siphons. Fish have gills instead of lungs, although some species of fish, such as the lungfish, have both. Marine mammals, such as dolphins, whales, otters, and seals need to surface periodically to breathe air.
There are over 200,000 documented marine species with perhaps two million marine species yet to be documented. Marine species range in size from the microscopic, including phytoplankton which can be as small as 0.02 micrometres, to huge cetaceans (whales, dolphins and porpoises), including the blue whale – the largest known animal reaching 33 metres (108 ft) in length. Marine microorganisms, including protists, bacteria and viruses, constitute about 70% of the total marine biomass.
The Emperor Penguin (Aptenodytes forsteri), at 1.3 metres (3 ft 9 in) tall and 32 kilograms in mass, is the tallest and heaviest of all penguins. It is the only penguin that breeds during the winter in Antarctica. Emperor Penguins eat mainly crustaceans (such as krill) but also occasionally indulge in small fish and squid. In the wild, Emperor Penguins typically live for 20 years, but some records indicate a maximum lifespan of around 40 years. The Emperor Penguin should not be confused with the King Penguin or the Royal Penguin.
Adults average about 1.3 metres (3 ft 9 in) and weigh 30 kilograms (75 lb) or more. The head and wings are black, the abdomen white, back bluish grey, and the bill is purplish pink. On the sides of the neck, there are two golden circular stripes.
Like the King Penguin counterpart, a male Emperor Penguin has an abdominal fold, the "brood pouch", between its legs and lower abdomen.
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Rachel Louise Carson (27 May 1907 – 14 April 1964) was a Pittsburgh-born zoologist and marine biologist whose landmark book, Silent Spring, is often credited with having launched the global environmental movement. Silent Spring had an immense effect in the United States, where it spurred a reversal in national pesticide policy.
Rachel Carson was born in 1907 on a small family farm near Springdale. As a child, she spent many hours learning about ponds, fields, and forests from her mother. She originally went to school to study English and creative writing, but switched her major to marine biology. Her talent for writing would help her in her new field, as she resolved to "make animals in the woods or waters, where they live, as alive to others as they are to me". She graduated from the Pennsylvania College for Women, today known as Chatham College, in 1929 with magna cum laude honors. Despite financial difficulties, she continued her studies in zoology and genetics at Johns Hopkins University, earning a master's degree in zoology in 1932.
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Did you know...
- Triggerfishes are the brightly coloured fishes of the family Balistidae. (pictured)
- The sea otter often keeps a stone tool in its armpit pouch.
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Photo credit: Raul654
Cuttlefish are sometimes called the chameleon of the sea because of their remarkable ability to rapidly alter their skin colour at will. Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage them from predators.
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