Ice, Water, Wind & Currents: Antarctica's shores change continually. The thick ice covering the continent and creates huge fridges known as ice shelves. Towering sections ice break off these shelves to form icebreakers. The seas surface is frozen around much of the continent. The ice swells from 1.5 million square miles at summer's end to nearly 6 8 million in winter. In spring the extra ice thaws and splits into floes. Father from Antarctica, the surface is larger ice free. Cold ocean currents sweep north and west until, at 50 to 60 degrees latitude, they meet warmer water and sink below it.

The belt where the currents meet is called the Antarctic Convergence. It forms the boundary of the Antarctic region. Inside the convergence, the water is surprisingly supportive is surprisingly supportive of life. The currents stir up deeper water that is rich in nutrients, and the cold water contains a lot of oxygen. Inshore, the richer waters tend to be in the pack ice zones, where light penetrates in summer. The fast swimming sei whale filters  fish and krill from the deep open sea off Antarctica. Like the rare blue whale, its population has dropped drastically because of whaling. The krill is a vital link in Antarctic food chain.

Mammals: The Wedeln seal is the mammal found closest to the South Pole. It can remain in iced over seas all winter because its body fat keeps out the cold. Using its teeth, it gnaws breathing holes in the ice. The crab eater seal swims under pack ice and feeds on krill. Its young often fall prey to the leopard seal, which also kills penguins.

Baleen whales including blue, humpback, and right whales, migrate to Antarctic seas in summer. Cruising in the water, they trap and stain huge mouthfuls of krill. The fat reserves that they gain from summer feeding sustain them when they go north to breed. Warmed by its thick body fat, the Weddell seal is a supreme diver. It uses echolocation to find its prey of fish its prey of fish and squid and squid in the dark waters under the solid coastal ice.

Birds: Colonies of seabirds, which sometimes have millions of individuals, crowd onto the ice free coasts and islands of the Antarctic seas. Outside the nesting season, albatrosses and petrels roam the seas in search of surface plankton and squid. Gulls, terns, and skuas remain in coastal waters, often near upwelling currents. Feathers provide food insulation against heat loss.

But naked feet are a liability for birds that perch on ice floes. To compensate, some gulls cold their blood before it reaches their feet. They recycle the warmth back into their bodies. Penguins are well insulated. Their dense plumage protects them from freezing winds and cold water. They also have an insulating layer of fat beneath their plumage. The rockhopper is a small but aggressive penguin that breeds on cliff tops.

Life in the Seas: Unlike the barren ice sheets of Antarctica, the surrounding seas ar rich in wildlife. As the pack ice melts in summer, tiny free floating plants known as phytoplankton start to bloom around nutrient rich currents. They are the principal food of many animals, including zoo plankton, krill and other crustaceans, squid, and fish. Shrimp like krill are among the most abundant animals in polar waters and are eaten by many flesh eaters. Huge swarms of krill have been seen near the surface in summer. In winter they descend deeper to feed on plankton remains.

Other invertebrates inhabit the shallow seabed around  Antarctica where mineral rich sediments accumulate. These invertebrates include filter feeding sponges, as well as mollusks, starfish, sea spiders, and sea slugs. Many fish are specially adapted for the cold. Some Antarctic cod have an anti freeze chemical in their body fluids that sustains them at temperatures below freezing.

Icebergs: Every year about 480 cubic miles of ice break off from the Antarctic ice sheet, forming icebergs in a process known as cavling. Often hundreds of feet across and just as deep., the icebergs drift in the surrounding seas. They pose hazard to shipping because just one ninth of the iceberg is visible.  The rest is hidden under the waves.

Sometimes vast sections of the ice selves drift away into the ocean to form icebergs of staggering dimensions. The greatest on record was sighted in 1956. At 208 miles long and 60 miles wide, it was the size of Maryland. As icebergs drift away from the continent, they start to melt and break into smaller chunks. Some develop irregular or fantastic shapes. Different sections melt at different rates, but a berg at different rates, but a berg may take several years to vanish completely. Drifting at a rate of about eight miles a day, some fragments travel as far north as the Antarctic Convergence before disappearing. With the relentless attack of harsh weather, icebergs slowly change from flat topped slabs into irregular, beautiful forms. As they drift away north, they become rounded and melt away.

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