<P> Antarctica's cold deserts have some of the least diverse fauna in the world . Terrestrial vertebrates are limited to sub-antarctic islands, and even then they are limited in number . Antarctica, including the subantarctic islands, has no natural fully terrestrial mammals, reptiles, or amphibians . Human activity has however led to the introduction in some areas of foreign species, such as rats, mice, chickens, rabbits, cats, pigs, sheep, cattle, reindeer, and various fish . Invertebrates, such as beetle species, have also been introduced . </P> <P> The benthic communities of the seafloor are diverse and dense, with up to 155,000 animals found in 1 square metre (10.8 sq ft). As the seafloor environment is very similar all around the Antarctic, hundreds of species can be found all the way around the mainland, which is a uniquely wide distribution for such a large community . Polar and deep - sea gigantism, where invertebrates are considerably larger than their warmer - water relatives, is common in this habitat . These two similar types of gigantism are believed to be related the cold water, which can contain high levels of oxygen, combined with the low metabolic rates ("slow life") of animals living in such cold environments . </P> <P> The rocky shores of mainland Antarctica and its offshore islands provide nesting space for over 100 million birds every spring . These nesters include species of albatrosses, petrels, skuas, gulls and terns . The insectivorous South Georgia pipit is endemic to South Georgia and some smaller surrounding islands . Ducks, the South Georgia pintail and Eaton's pintail, inhabit South Georgia, Kerguelen and Crozet . </P> <P> The flightless penguins are almost all located in the Southern Hemisphere (the only exception is the equatorial Galapagos penguin), with the greatest concentration located on and around Antarctica . Four of the 18 penguin species live and breed on the mainland and its close offshore islands . Another four species live on the subantarctic islands . Emperor penguins have four overlapping layers of feathers, keeping them warm . They are the only Antarctic animal to breed during the winter . </P>

How many species of animals are there in antarctica