Antarctica - Biodiversity

Biodiversity

Few terrestrial vertebrates live in Antarctica. Invertebrate life includes microscopic mites like the Alaskozetes antarcticus, lice, nematodes, tardigrades, rotifers, krill and springtails. The flightless midge Belgica antarctica, up to 6 millimetres (0.2 in) in size, is the largest purely terrestrial animal in Antarctica. The Snow Petrel is one of only three birds that breed exclusively in Antarctica.

A variety of marine animals exist and rely, directly or indirectly, on the phytoplankton. Antarctic sea life includes penguins, blue whales, orcas, colossal squids and fur seals. The Emperor Penguin is the only penguin that breeds during the winter in Antarctica, while the Adélie Penguin breeds farther south than any other penguin. The Rockhopper Penguin has distinctive feathers around the eyes, giving the appearance of elaborate eyelashes. King Penguins, Chinstrap Penguins, and Gentoo Penguins also breed in the Antarctic.

The Antarctic fur seal was very heavily hunted in the 18th and 19th centuries for its pelt by sealers from the United States and the United Kingdom. The Weddell seal, a "true seal", is named after Sir James Weddell, commander of British sealing expeditions in the Weddell Sea. Antarctic krill, which congregates in large schools, is the keystone species of the ecosystem of the Southern Ocean, and is an important food organism for whales, seals, leopard seals, fur seals, squid, icefish, penguins, albatrosses and many other birds.

A census of sea life carried out during the International Polar Year and which involved some 500 researchers was released in 2010. The research is part of the global Census of Marine Life (CoML) and has disclosed some remarkable findings. More than 235 marine organisms live in both polar regions, having bridged the gap of 12,000 km (7,456 mi). Large animals such as some cetaceans and birds make the round trip annually. More surprising are small forms of life such as mudworms, sea cucumbers and free-swimming snails found in both polar oceans. Various factors may aid in their distribution – fairly uniform temperatures of the deep ocean at the poles and the equator which differ by no more than 5 °C, and the major current systems or marine conveyor belt which transport egg and larvae stages.

The climate of Antarctica does not allow extensive vegetation. A combination of freezing temperatures, poor soil quality, lack of moisture, and lack of sunlight inhibit plant growth. As a result, the diversity of plant life is very small and limited in distribution. Excluding organisms which are not plants (algae and fungi, including lichen-forming species), the flora of the continent largely consists of bryophytes (there are about 100 species of mosses and 25 species of liverworts), with only two species of flowering plants, both found in the Antarctic Peninsula: Deschampsia antarctica (Antarctic hair grass) and Colobanthus quitensis (Antarctic pearlwort). Growth generally occurs in the summer, and only for a few weeks at most.

About 1150 species of fungi have been recorded from Antarctica, of which about 750 are non-lichen-forming and 400 are lichen-forming. Some of these species are cryptoendoliths as a result of evolution under extreme conditions. Seven hundred species of algae exist, most of which are phytoplankton. Multicolored snow algae and diatoms are especially abundant in the coastal regions during the summer. Recently ancient ecosystems consisting of several types of bacteria have been found living trapped deep beneath glaciers. The autotrophic community is made up of mostly protists.