The Antarctic realm is one of eight terrestrial

biogeographic realm A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions. De ...

s. The ecosystem includes

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

and several island groups in the southern

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

and

Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...

oceans. The continent of Antarctica is so cold that it has supported only 2 vascular plants for millions of years, and its flora presently consists of around 250 lichens, 100 mosses, 25-30 liverworts, and around 700 terrestrial and aquatic

alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

l species, which live on the areas of exposed rock and soil around the shore of the continent. Antarctica's two flowering plant species, the Antarctic hair grass (''

Deschampsia antarctica ''Deschampsia antarctica'', the Antarctic hair grass, is one of two flowering plants native to Antarctica, the other being ''Colobanthus quitensis'' (Antarctic pearlwort). They mainly occur on the South Orkney Islands, the South Shetland Island ...

'') and Antarctic pearlwort (''

Colobanthus quitensis ''Colobanthus quitensis'', the Antarctic pearlwort, is one of two native flowering plants found in the Antarctic region. It has yellow flowers and grows about 5 cm (two inches) tall, with a cushion plant, cushion-like growth habit that gives it a ...

''), are found on the northern and western parts of the Antarctic Peninsula. Antarctica is also home to a diversity of animal life, including penguins, seals, and

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s. Several Antarctic and sub-Antarctic island groups are considered part of the Antarctic realm, including

Bouvet Island Bouvet Island ( ; or ''Bouvetøyen'') is an island claimed by Norway, and declared an uninhabited protected nature reserve. It is a subantarctic volcanic island, situated in the South Atlantic Ocean at the southern end of the Mid-Atlantic R ...

, the Crozet Islands,

Heard Island The Territory of Heard Island and McDonald Islands (HIMI) is an Australian external territory comprising a volcanic group of mostly barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size ...

, the Kerguelen Islands, the

McDonald Islands The McDonald Islands () are an uninhabited archipelago in the southern Indian Ocean in the vicinity of Heard Island (). Together with Heard Island, they make up the Australian external Territory of Heard Island and McDonald Islands. The McDona ...

, the

Prince Edward Islands The Prince Edward Islands are two small uninhabited islands in the sub-Antarctic Indian Ocean that are part of South Africa. The islands are named Marion Island (named after Marc-Joseph Marion du Fresne, 1724–1772) and Prince Edward Island ...

, the South Georgia Group, the South Orkney Islands, the

South Sandwich Islands ) , anthem = "God Save the King" , song_type = , song = , image_map = South Georgia and the South Sandwich Islands in United Kingdom.svg , map_caption = Location of South Georgia and the South Sandwich Islands in the southern Atlantic Oce ...

, and the

South Shetland Islands The South Shetland Islands are a group of Antarctic islands with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the nearest point of the South Orkney Islands. By the Antarctic Treaty of 1 ...

. These islands have a somewhat milder climate than Antarctica proper, and support a greater diversity of

tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless mou ...

plants, although they are all too windy and cold to support trees. Antarctic krill is the keystone species of the ecosystem of the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

, and is an important food organism for

s, seals,

leopard seal The leopard seal (''Hydrurga leptonyx''), also referred to as the sea leopard, is the second largest species of seal in the Antarctic (after the southern elephant seal). Its only natural predator is the orca. It feeds on a wide range of prey incl ...

fur seal Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family '' Otariidae''. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively l ...

crabeater seal The crabeater seal (''Lobodon carcinophaga''), also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized (over 2 m in length), relatively slender and pale-c ...

s, squid, icefish, penguins, albatrosses and many other

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s. The ocean there is so full of phytoplankton because water rises from the depths to the light-flooded surface, bringing nutrients from all oceans back to the photic zone. On August 20, 2014, scientists confirmed the existence of

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s living below the ice of

History

Millions of years ago, Antarctica was warmer and wetter, and supported the

Antarctic flora Antarctic flora are a distinct community of vascular plants which evolved millions of years ago on the supercontinent of Gondwana. Presently, species of Antarctica flora reside on several now separated areas of the Southern Hemisphere, includin ...

, including forests of podocarps and

southern beech ''Nothofagus'', also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America (Chile, Argentina) and Australasia (east and southeast Australia, New Zealand, New Gui ...

. Antarctica was also part of the ancient supercontinent of Gondwanaland, which gradually broke up by

continental drift Continental drift is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift has been subsumed into the science of pl ...

starting 110 million years ago. The separation of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

from Antarctica 30-35 million years ago allowed the Antarctic Circumpolar Current to form, which isolated Antarctica climatically and caused it to become much colder. The Antarctic flora subsequently died out in Antarctica, but is still an important component of the flora of southern

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

(

Latin America and the Caribbean The term Latin America and the Caribbean (LAC) is an English-language acronym referring to the Latin American and the Caribbean region. The term LAC covers an extensive region, extending from The Bahamas and Mexico to Argentina and Chile. The ...

) and

Australasian realm The Australasian realm is a biogeographic realm that is coincident with, but not (by some definitions) the same as, the geographical region of Australasia. The realm includes Australia, the island of New Guinea (comprising Papua New Guinea and th ...

s, which were also former parts of Gondwana. Some botanists recognize an

Antarctic Floristic Kingdom The Antarctic Floristic Kingdom, also the Holantarctic Kingdom, is a floristic kingdomTakhtajan, A. (1986). ''Floristic Regions of the World''. (translated by T.J. Crovello & A. Cronquist). University of California Press, BerkeleyPDF

that includes Antarctica,

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, and parts of Temperate South America where the Antarctic Flora is still a major component.

Ecoregions

The Antarctic realm is divided into 17

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

s:Eric Dinerstein, David Olson et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545, https://doi.org/10.1093/biosci/bix014

References

Bibliography

* *

Life in the Freezer ''Life in the Freezer'' is a BBC nature documentary series written and presented by David Attenborough, first transmitted in the United Kingdom from 18 November 1993. A study of the seasonal cycle of Antarctica, it was the first of Attenborou ...

, a

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