Antarctica
There’s little southern comfort for animals clinging on to survive in Antarctica’s unforgiving landscape of ice.
The southernmost continent in the world is the fifth largest. About 98 per cent of it is covered permanently by ice with an average thickness of 1.9km. Yet, despite all that ice and with little more than 100mm of precipitation per year, Antarctica is technically a desert, the largest on Earth. It is, however, cold… very cold!
The coldest air temperature ever recorded by conventional means was –89.4°C at Russia’s Vostok Station in July 1983, but sensors mounted on satellites have located even colder temperatures. On the East Antarctic Plateau ground temperatures regularly reach –98°C during a polar winter night, the coldest place on the planet.
Living on the edge
As ice dominates life on the Antarctic mainland and in the surrounding Southern Ocean, it is a challenging place for living organisms to survive, but survive they do, with the snow petrel and Antarctic skua breeding the furthest south of any animal. They nest on rocky outcrops that stick out of the ice, some sites up to 440km from the sea. Aside from emperor, chinstrap and Adélie penguins, which nest on Antarctica, there is precious little else. Residents are no bigger than mites, nematodes, springtails and water bears, along with algae, fungi, lichens, mosses, liverworts and a couple of small plants, mostly on the Antarctic Peninsula.
Sea-ice surrounds the continent, doubling its size as the sea freezes in winter. Under that ice is a completely different world, where invertebrates reign supreme. The Seven Worlds team dived below the ice in McMurdo Sound, the southernmost navigable body of water, and found the sea
floor covered by colourful starfish, brittlestars, feather stars, sea urchins, sea cucumbers, cup corals and sea anemones, a far cry from the blackand-white world at the surface.
Some animals have grown into giants, like the sea spiders with a leg span of 14cm, and, while the crew were there, they witnessed something unusual. A jellyfish’s stinging tentacle had made contact with a sea anemone, and began to reel it in. What it hadn’t realised is that the anemone was attached to the bottom, and it was actually reeling itself towards a sticky end!
Cold, hard choices
In amongst the sea-ice lives the Weddell seal, which occurs the farthest south of any mammal. It can only survive amongst the ice by creating several breathing holes that it keeps open by scraping the ice with its teeth. When its teeth wear down, it either starves, because it cannot catch fish, or it drowns because the breathing holes freeze over. The Weddell seal, not surprisingly, is the seal with the shortest lifespan. Life in the Antarctic either embraces ice – like the snow petrels and Weddell seals – or avoids it, by living more to the north, on and around subantarctic islands, as elephant seals, king penguins and albatrosses do. The price they pay, however, is that they are not alone. They must compete for food and living space with millions of others.
The Seven Worlds Antarctic team headed for South Georgia, home to elephant seals and king penguins. For wildlife cameraman Mark MacEwen, the first sight of the island was beyond anything he’d dreamed.
“St Andrew’s Bay is an amazing amphitheatre with a huge crescent of beach backed by jutting mountains. As you drop anchor just offshore, the sound of what amounts to a wildlife chorus hits you. There are the deep bass guttural calls of the bull elephant seals, which reverberate across the
“You could feel the tension on the beach. The sound at the moment the male elephant seals clashed could be felt through the ground.”
bay, mixed with the cries of hundreds of thousands of king penguins.”
The crew were there to film the epic battles between bulls, and the comings and goings of penguin parents. Mark took on the seals.
Battle of the giants
“Male elephant seals are huge,” Mark recalls, “like nothing you’ve ever seen before. A mass of blubber up to 5.8m long and weighing 4,000kg. But they are surprisingly fast for an animal of that size.
“We were there to capture the moment when large single males try to take over the harems, and you can feel the tension on the beach. I wanted to get in amongst the fighting, and the animals would tower above me. The sound at the moment they clashed could be felt through the ground. It reminded me of that moment in Jurassic Park when a tramping T. rex made ripples in the glass of water!”
The seals were not the only giants to be featured in the Antarctic episode. One of the more encouraging stories, from a conservation point of view, was the return of the great whales. Humpback whales are now bubblenet feeding in large numbers and southern right whales have returned to their former breeding and feeding sites. But the biggest surprise was the sight of hundreds of fin whales – the world’s second largest animal – feeding on krill swarms in Drake Passage, possibly the largest aggregation of great whales ever filmed.