Antarctica, with its extreme cold, vast ice sheets, and powerful winds, might seem uninhabitable. Yet, the Southern Ocean and the continent support a surprising array of life. Organisms here have developed remarkable adaptations to survive near-freezing temperatures and long periods of darkness.
Giants of the Antarctic Seas
Antarctica’s waters host large marine mammals dependent on abundant food sources in these cold, nutrient-rich seas. Prominent whales include:
Blue whales, the largest animals on Earth, feed predominantly on krill.
Fin whales, the second-largest whale species, are known for being the fastest swimmers among the great whales.
Humpback whales are recognized for their distinctive long pectoral fins and their acrobatic breaches.
Minke whales are the smallest baleen whales found in Antarctica.
Orcas, or killer whales, are apex predators hunting seals, penguins, and other whales. They are the largest members of the dolphin family.
Seals also thrive in the Antarctic environment, with six species commonly found: Weddell, crabeater, leopard, Ross, elephant, and Antarctic fur seals. Their thick blubber insulates them against frigid water and serves as an energy reserve.
Weddell seals are commonly observed along the Antarctic Peninsula and are skilled deep divers, hunting fish and krill. Crabeater seals, despite their name, primarily consume krill, using specialized sieve-like teeth to filter these small crustaceans from the water. Leopard seals are formidable predators that feed on krill, fish, penguins, and other seals. Elephant seals, the largest seal species, spend much of their lives in the water and come ashore to breed and molt.
Feathered Inhabitants of Antarctica
Antarctica’s skies and coastlines host various bird species, with penguins being the most iconic. Emperor and Adélie penguins live exclusively on the continent and its surrounding waters. Emperor penguins, the tallest and heaviest species, breed during the harsh Antarctic winter; males incubate a single egg for over two months without feeding. Adélie penguins are highly dependent on sea ice and are abundant along the Antarctic coast, forming large colonies on ice-free slopes.
Other penguin species, like chinstrap and gentoo, inhabit the northern Antarctic Peninsula and sub-Antarctic islands, where conditions are slightly less severe. Chinstrap penguins are identifiable by a narrow black band under their chin and feed primarily on krill. Gentoo penguins have bright orange-red beaks and white patches over their eyes, and are among the fastest swimming penguins. Beyond penguins, various seabirds, including albatrosses, petrels, skuas, and terns, inhabit the region, their life cycles linked to the marine food web. Many birds adapt with dense, waterproof feathers and a fat layer for insulation.
Life Beneath the Ice
The frigid waters beneath Antarctica’s surface teem with a diverse array of life, forming the base of the continent’s intricate food web. Antarctic krill are small crustaceans and a keystone species, forming immense swarms that provide the primary food source for most marine mammals and seabirds. They feed on phytoplankton, connecting primary production to higher trophic levels.
Fish in Antarctic waters have developed unique adaptations to survive in sub-zero temperatures. Many species, including the Antarctic toothfish, produce antifreeze glycoproteins that prevent their bodily fluids from freezing. These proteins bind to ice crystals and inhibit their growth, allowing the fish to maintain liquid blood even when water temperatures drop below freezing. Icefish are particularly remarkable as they are the only adult vertebrates that lack the oxygen-transporting protein hemoglobin, resulting in transparent blood.
Other invertebrates also inhabit the Southern Ocean, contributing to its rich biodiversity, including squids, jellyfish, sea spiders, sponges, and starfish. Recent discoveries have even revealed unexpected life forms, such as lobster-like creatures, thriving in subglacial river systems beneath hundreds of meters of ice.
Tiny Dwellers of the Continent
While the marine environment supports vast life, terrestrial life on the Antarctic continent is much sparser, limited to ice-free areas. These land-based ecosystems are dominated by microscopic and invertebrate organisms that have adapted to the extremely arid and cold conditions. Among these are mites and springtails, found in mosses, lichens, and soil.
Microscopic animals like tardigrades and nematodes also inhabit these harsh environments. These tiny creatures withstand extreme conditions like desiccation, freezing, and radiation by entering suspended animation. They play a role in the limited terrestrial food web, often feeding on bacteria, algae, and decaying organic matter.