The lack of unfrozen water, combined with the extreme cold and wind, make Antarctica arguably the harshest environment on Earth, and thus relatively few species live year-round on the Antarctic continent itself.
The only permanent inhabitants are invertebrates, and the largest of these is an insect, the wingless midge, which only grows to 0.5 inches long. Similarly, no flowering plants exist in Antarctica and only two higher plantsa grass and a pearlwort. All the other plants are mosses, lichens and algae. Adapted to the extreme climate, these are incredibly hardy: Mosses have been recorded at 86°42'South, just more than 200 miles from the South Pole.
Seals, penguins and seabirds all live and feed along the Antarctic coast, but most leave the continent in wintertime. The one creature that appears to have defied nature to survive the darkness and cold of the desperate Antarctic winter is the Emperor penguin, the largest of all the Antarctic birds.
The story of the breeding cycle of the Emperor penguin is one of the great wonders of Antarctic survival. The Emperor has evolved several unique characteristics to live and breed in this hostile climate. The Emperor female lays one egg in June and leaves the land to spend the winter feeding at sea. The male remains to look after the egg throughout the long winter, holding it on his feet under the skin of the abdomen. The males endure nine weeks without food, during which they lose up to 40 percent of their body weight. The males huddle together in colonies and take turns rotating from the colder outer edge of the colony to the warmer inner core. To reduce heat loss, they recover 80 percent of the heat in their breath through a complicated series of nasal passages. The females return close to hatching time and take over the feeding and protection of the chicks while the males return to the sea to feed.
The coastal seas are rich in life, with Gentoo, Adelie and Chinstrap penguins; Weddell, Ross, Crabeater and Leopard seals; and Humpback, Fin, Right and the mighty Blue whales, the largest creatures on Earth. All of this life is founded upon two tiny organismsalgae in the sea ice and the phytoplankton in the water below. These are the primary producers of the Antarctic food chain, the basic building blocks of life in the South.
As the sea ice builds up at the beginning of winter, algae and nutrients from the sea below become layered into the ice until the winter darkness prohibits photosynthesis and further growth. When spring arrives and light returns, the algae in the ice grow rapidly. As the ice melts, the algae sink into the water to provide food for microscopic fauna and plankton. These in turn provide food for krill and fish, which in turn feed seals, penguins and seabirds.
The cold, nutrient-rich water of the Southern Ocean is ideal for the growth of phytoplankton. The phytoplankton blooms every spring and summer and is the main food of krill, the staple food of the baleen whales and some seals and penguins.
The simplicity of this particular food web means that the ecosystem is sensitive to any disturbances. The distribution of algae and phytoplankton in the Southern Ocean is influenced by the complex interaction of the Antarctic Circumpolar Current, the East Wind Drift and the position of the Antarctic Convergence.
The Antarctic Circumpolar Current is an extremely powerful current that flows eastwards around the Antarctic at a rate about four times faster than that of the Gulf Stream. Where this is forced through the gap of the Drake Passage, between Tierra del Fuego and the tip of the Antarctic Peninsula, it speeds up even faster.
The Antarctic Convergence is the boundary around the Antarctic in which Antarctic Bottom Water, the cold dense water of the Southern Oceanformed when ice shelves melt and the water sinks to the ocean flooris drawn north away from the Antarctic continent where it meets warmer water and sinks underneath it. Where the two types of water mix, upwelling of nutrients from the Antarctic Bottom Waterin which oxygen dissolves easily, encouraging the breeding of marine organismsprovides an immense supply of food for seals, whales, penguins and seabirds. The boundary of the Convergence has changed throughout time and is the subject of continuing oceanographic investigation. The Antarctic Convergence profoundly influences the climates and ecosystems of the islands surrounding Antarctica.
Photo Credits: Seal, © 2000 WGBH, Photo: Paul Marotta
Penguin, © 1999 WGBH and PBS, Photo: Kelly Tyler
See the Film Trailer | Where to See the Film | Special Events | For Parents & Teachers | Email a Postcard to a Friend | Merchandise | WGBH Giant-Screen Film Distribution