 Only a few microorganisms and small plants live inland; almost all forms of higher life survive on the coasts of Antarctica, on and under the ice. Despite the cold, they thrive. There is constant movement of water around Antarctica; as these waters combine with the warmer waters of the Atlantic, Pacific and Indian Oceans, the cold Antarctic water sinks, causing an upwelling of nutrients and minerals from the bottom. This is known as the Antarctic Convergence. The Antarctic ocean ecosystem is simple, with few species, yet vast numbers of each are supported. The nutrients in the cold water are directly used by phytoplankton. These single-celled floating plants use the sun's energy, water, and carbon dioxide in the water to do photosynthesis, forming glucose and oxygen. This stored energy forms the bottom of the Antarctic food chain. 
PenguinsAll seventeen penguin species live in the southern hemisphere, and the greatest numbers of them can be found on the Antarctic coasts and Antarctic islands. Penguins live along the western and southern coasts of South America, the tip of Africa, southern Australia, New Zealand, and all around Antarctica. One species, the Galapagos penguin, lives on the equator. Seven kinds of penguins visit Antarctica, but only two species, the Adelie and Emperor penguins, breed exclusively there. Penguins are the only birds that migrate by swimming. They may migrate up the west or east coasts of South America, as far north as Chile or Rio de Janeiro in Brazil. Penguins, like all cold water marine creatures, have a layer of blubber under their skin which keeps them warm. 
AlbatrossesAlbatrosses are the largest seabirds, with a wing span up to 3 m and a mass up to 12 kg. Some live as long as 60 years. They also have one of the lowest reproductive rates of any bird, laying a single egg sometimes only every second year, and most take 10 years to reach sexual maturity. Albatrosses cover long distances when foraging, covering thousands of square kilometres of ocean. Wandering albatrosses range from sub-tropical to Antarctic waters on trips covering up to 10,000 km in 10-20 days. Several species migrate long distances, and some (like Royal and Wandering albatrosses) travel right round the Earth! 
WhalesThere are two types of whales common to the region, toothed and baleen. Toothed whales include the large sperm whales, which prey on fish and squid, and killer whales (right), which prey on fish, penguins, seals and other whales. Baleen whales, such as the blue whale and humpback, have fibrous plates of baleen instead of teeth, which they use to strain plankton from seawater. 
SealsThere are also two types of seals here, true seals and fur seals. Fur seals (related to sea-lions) are pictured on the left. Depending on the species, seals feed on fish, squid and krill. The Leopard seal also eats penguins and other seals. Thick layers of blubber beneath the skin of whales and seals are a food reserve, and insulation from the cold. Seals also have a layer of fur, giving additional insulation on land. Fish Of the 20,000 species of fish in the world, only about 200 live in the cold Antarctica sea. The temperature of the oceans around Antarctica varies only from about -2°C to 0°C. Sea ice freezes at about -1.8°C, which is only about 1°C lower than the freezing point of many species of fish. Antarctic fish show unusual and highly successful adaptations to these cold temperatures. Many species accumulate sodium, potassium, chloride ions or urea, which lowers the freezing point of their bodies. Others have special proteins that act like anti-freeze, preventing the growth of ice crystals in their bodies. Another fascinating adaptation is the lack of haemoglobin in Antarctic fish. (Haemoglobin is the red-coloured chemical in red blood cells, which carries oxygen around the bodies of every other vertebrate species). This is a useful adaptation, as oxygen is highly soluble in cold seawater. This also makes their blood thinner, allowing their metabolism to be slower, which conserves energy. |