With temperatures reaching down to almost -60°C (-76°F), the Antarctic is the most inhospitable place on Earth. Surrounded by pack ice for much of the year, as well as ice shelves and glaciers dating back centuries, the icy continent receives surprisingly little fresh snow, with only 50mm on average falling each year. And yet, its land, seas, and skies are teeming with life in a unique ecosystem of permanent residents and summer visitors. So, just how do Antarctic mammals, birds, and fish survive in such a harsh environment?
The White Desert
With even less frequent rainfall than Chile’s Atacama Desert, Antarctica is the coldest, emptiest, and driest place on Earth. Its Dry Valleys in fact, located off the McMurdo Sound in the Ross Dependency claimed by New Zealand, haven't seen rain in nearly two million years and form the basis of Antarctica’s claim to being the driest place on Earth. This doesn't mean however though that there’s no water here at all.
Water in the Dry Valleys is a zero-sum game, with water neither gained nor lost. In the summer, katabatic winds, heavy winds filled with moisture, are pulled down by gravity from the surrounding mountains and away from the snow-free Wright and Taylor Valleys to form Antarctica’s longest river, the Onyx River, a meltwater stream that flows only in summer, away from the ocean for 19 miles into Lake Vanda. Seven times more saline than seawater with high concentrations of both nitrous oxide and hydrogen, this increasingly briny river is home only to a variety of bacteria, algae, and microbes, which, incidentally, shot to fame in 2002 when they were thawed after being cryogenically frozen for nearly 3,000 years and brought successfully back to life.
Birds and Penguins
This most inhospitable area of Antarctica, surrounding the Ross Sea, which includes Ross Island and its terrifyingly named Mount Terror, mentioned by Jules Verne in his 20’000 Leagues Under The Sea, contains Antarctica’s largest Marine Protected Area and is the breeding site of one third of all Adélie penguins in the world. One of only two penguin species that live exclusively on Antarctica all year round, Adélie penguins choose to breed on bare, rocky ground where snow is not likely to accumulate, building nests of stones during the Antarctic summer to protect their eggs and chicks. And unlike more northerly parts of Antarctica, seeing increased effects from climate change, here there is no rain or puddles to harm their unhatched eggs.
Feeding largely on krill, Adelie penguins have little access during the breeding season to fresh water. With only highly saline water available to drink, they have a unique ability to regulate their salt intake by expelling salt compounds through nasal salt glands. Surrounded by sea ice all year round, Adélie penguins move on to ice floes after the breeding season to molt before then migrating over 13,000 kilometers during the Antarctic winter to the edge of the pack ice where the sun can still be seen, even if it no longer rises south of the Antarctic Circle.
Unlike Gentoo or Chinstrap penguins, both Adélie and Emperor penguins are highly adapted to life in the high Antarctic and are the only two species of penguin to successfully breed on the icy continent. And along the edge of the Ross Sea is a great place to spot these two species of penguins that live exclusively on Antarctica. Often found breeding on a headland at Taylor Glacier, Emperor penguins, the only species to breed during the Antarctic winter, have adapted to survive the cold with dense feathers and a thick layer of fat to enable it to incubate their eggs over two months while withstanding temperatures down to -40 °C and up to 144 km/h winds. And with very little in the way of vegetation to support any kind of life inland, all life in this part of Antarctica is dependent on the sea and coastline. Emperor Penguins can dive to depths of over 500 meters for over 20 minutes thanks to their uniquely dense bone structure, where they feed on fish, crustaceans, and the Antarctic Silverfish.
Besides penguins, you’ll also find a wide variety of birds both on land and circling the skies over the Southern Ocean. Cape Bird, named after Lieutenant Edward J. Bird of the Ross expedition on HMS Erebus rather than its bird colonies, is the breeding site of the Antarctic Skua, which besides penguin chicks and other seabirds, mostly feeds by stealing fish from other birds. Here you’ll also find the Chinstrap Penguin, Southern Giant Petrel, Antarctic Fulmar, Antarctic Petrel, Snow Petrel, Wilson's Storm Petrel, Southern Great Skua, Southern Black-backed Gull, and Black-browed Albatross, drawn to the krill-rich seas here.
Fish, Whales, and Seals
Otherwise known as the Antarctic herring, the Antarctic Silverfish has largely disappeared from the Northern Antarctic, but due to their large schools and high caloric value, are extremely important to the ecosystem in the Ross Sound. A pelagic species, this approximately 15cm long fish feeds at depths up to nearly 800 meters, on sea snails, zooplankton and bioluminescent copepods. Also preyed upon by Emperor penguins is the Antarctic toothfish, which is able to feed at the bottom of the Southern Ocean at depths over 2,000 meters, as is uniquely adapted to survive the subzero temperatures of the Ross Sea thanks to the antifreeze glycoproteins it produces in its blood.
Antarctic toothfish are prey to both Adelie and Emperor penguins as well as Weddell seals, minke whales, and Orcas, and while fish and krill are close to the bottom of the food chain here, various squid species are also fed upon by petrels, penguins, albatrosses, seals, and whales, including the glacial squid, giant warty squid, and the Antarctic neosquid, that lives deep in the frigid waters of the Ross Sea. There’s also the Colossal squid, a gigantic creature from the deep, such as the kraken weighing in at 350 kgs and measuring over three meters in length now displayed in New Zealand's Te Papa Museum.
Attracted by the vast quantities of krill, the frigid waters of the Ross Sea are also home to Humpback whales and Minke whales, one of the few species of Antarctic whale not to head north to warmer climes to breed, dependent instead on ice for their breeding grounds. Preliminary studies have also recently revealed three different ecotypes of Orca in the Antarctic, Type A, which prefers to hunt Minke whales in the open, ice-free waters of the Southern Ocean, Type B, the largest of the killer whales, which hunts seals in pods around the Gerlache Strait, and Type C, the smallest of the Orcas, which feeds on Toothfish among the ice floes of Ross Island, diving to between 400-700 meters in order to catch them.
Also feeding in the rich waters around the Antarctic continent on a diet of squid, fish, and the richly nourishing Antarctic silverfish are a variety of seals, including Leopard seals, Crabeater seals and the eponymous Ross seals. Perhaps one of the rarest of the Antarctic seals, Ross Seals confine themselves almost entirely to the pack ice. With snub noses and short fur, they feed on squid, fish, and the richly nourishing Antarctic silverfish, and are in turn also preyed upon by Orcas and Leopard Seals, also attracted to the area by the pack ice. The number of Weddell seals here however remains extremely depleted, following the expeditions to the South Pole over the last century, which saw the Weddell seals used as food for sled dogs.
If you’re looking to discover the Antarctic’s White Desert and its unique wildlife, take a look at our trips to the southwest side.