Life in Antarctica

Antarctic krill, Euphausia superba, is a small shrimp-like crustacean up to about 6 centimeters long. It lives in swarms that can cover kilometers and feeds on the microscopic algae that grow in the sea and under the sea ice.

The best estimate of the total krill in the Southern Ocean is about 379 million tons, according to CCAMLR, the commission that regulates fishing in the region. It is one of the largest biomass concentrations of a single animal species on Earth, larger than that of all humanity.

Almost all the large animals of Antarctica eat krill or eat animals that eat krill: whales, seals, penguins, birds and fish. For this reason, krill fishing is limited by CCAMLR, and annual catches remain below 1% of the total estimate.

Krill depends on sea ice: the algae that grow under the ice feed the larvae in winter. Less sea ice tends to mean less krill, which affects the entire food chain.

Only two penguin species actually live on the continent and raise chicks around it: the emperor and the Adélie. The emperor penguin is the largest of all, about 1.1 meters tall and up to nearly 40 kilograms. The Adélie, smaller, makes pebble nests on the ice-free coastal rock.

The emperor breeds on sea ice attached to the coast in winter. The female lays an egg in May or June and returns to the sea; the male incubates the egg on his feet for about two months, without eating, in the cold and dark. There are about 250,000 breeding pairs, all in Antarctica, according to a 2020 satellite census.

In 2025, a British Antarctic Survey study using satellite images of 16 colonies on the Peninsula and in the Weddell and Bellingshausen Seas, about one third of the species, showed a 22% decline between 2009 and 2024. The main cause is the loss of the sea ice where chicks grow.

On the Peninsula and nearby islands the gentoo penguin, with an orange bill, and the chinstrap penguin, with a black band under the chin, also live. The king penguin, similar to the emperor but smaller, raises chicks on subantarctic islands such as South Georgia, not on the continent.

Six seal species live in Antarctica and nearby islands. The Weddell seal is the mammal that lives farthest south on the planet: it spends the winter under the sea ice, keeps breathing holes by scraping the ice with its teeth and dives to about 600 meters, sometimes for more than an hour.

The crabeater seal, despite its name, does not eat crabs: it eats krill, which it filters with densely spaced teeth. It is the most numerous seal in the world. The leopard seal, solitary with a large head, hunts penguins, pups of other seals, fish and krill.

The southern elephant seal is the largest seal in the world: males exceed 4 meters and can weigh several tons. It dives beyond 1,000 meters. Completing the list are the Ross seal, rare and little studied, which lives in dense ice, and the Antarctic fur seal, which almost disappeared from 19th-century sealing and has since recovered.

About ten cetacean species live in or pass through the Southern Ocean. Most large whales come in summer to feed on krill and return in winter to warmer waters to give birth.

The blue whale, the largest animal that has ever existed, frequents these waters, as do the fin whale, humpback, minke and southern right whale. The orca, which is a dolphin, has groups specialized in hunting seals, penguins or fish.

In the 20th century, industrial whaling killed more than 2 million whales in the southern hemisphere, especially in the Southern Ocean, and drove the Antarctic blue whale near extinction. Some species, like the humpback, have recovered well since commercial whaling ended; the blue whale remains far below its former numbers. The history of whaling is in History and exploration.

Besides penguins, Antarctica and surrounding islands host dozens of seabird species. Most arrive in summer to breed and spend the rest of the year at sea.

The wandering albatross has the largest wingspan among living birds, up to about 3.5 meters. It glides over the Southern Ocean for thousands of kilometers almost without flapping, using the wind. It raises chicks on subantarctic islands like South Georgia.

The petrels are the most numerous group. The snow petrel, all white, nests in mountains hundreds of kilometers from the coast, farther inland than any other bird. The brown skua hunts penguin eggs and chicks and has even been seen at the South Pole.

The water around Antarctica is about −1.9 °C, below the freezing point of fresh water, but it does not freeze because of the salt. At that temperature, the blood of most fish would turn to ice.

About nine in ten fish of the Southern Ocean are notothenioids, a group that evolved antifreeze proteins. These glycoproteins attach to ice crystals that form in the body and prevent them from growing.

Icefish, a family within this group, are the only adult vertebrates without hemoglobin: their blood is almost transparent. They survive because cold water holds a lot of dissolved oxygen and because they have large hearts and a lot of blood.

Only two flowering plants are native to Antarctica: the Antarctic hair grass, Deschampsia antarctica, and Colobanthus quitensis, a small cushion plant. Both live on the Peninsula and nearby islands, almost always below 100 meters elevation.

Vegetation is dominated by mosses, with about 111 species, and lichens, with about 400 species, according to the herbarium of the British Antarctic Survey. Lichens, a partnership of a fungus and an alga, even grow on inland rocks, a few degrees from the South Pole.

Everything grows very slowly. In the Dry Valleys, some lichens increase by about 1 millimeter per century, and a footprint on a moss carpet can remain visible for years. For this reason, the Treaty rules protect these areas and require care not to bring in seeds from elsewhere.

The largest animal that lives only on land in Antarctica is a wingless midge, Belgica antarctica, 2 to 6 millimeters long. It is the only insect found exclusively in Antarctica and occurs on the Peninsula and the South Shetlands. Penguins and seals do not count, because they depend on the sea for food.

In soil and moss live mites, springtails, tardigrades and microscopic worms called nematodes. Many survive the cold by losing almost all the water in their bodies and coming back to life when the ice melts.

Microscopic life goes even further. In the Dry Valleys there are bacteria and algae living inside rocks, sheltered from the wind. In subglacial lakes, such as Whillans, drilled in 2013, microbes have been found that live in the dark, deriving energy from minerals, as described in The Ice of Antarctica.