The Open Door Web Site
The Great Southern Ocean
Blue Whale skeleton, Antarctica
Antarctica is the world's last continent. It covers 14 million km2, which is twice the surface area of Australia and one and a half times the surface area of the United States of America. In winter, when the sea-water surrounding the continent freezes, the area of Antarctica effectively doubles. In the summer months only 2% of this icy continent is uncovered by ice. Most of this exposed 2% of land is found on the Antarctic peninsula which lies about 900km due south of Chile in South America.
Many millions of years ago Antarctica formed part of a massive land mass called Gondwanaland. At that time Antarctica, while it was still joined to South America, Australia and South Africa, had a temperate climate. The continent was covered with forests, and plant and animal life was abundant.
These four great continents broke away from each other and drifted to different parts of the globe. Antarctica finally settled at the South Pole and became covered by a thick ice cap. Fossils of animals and plants which have been found in Antarctica provide the evidence that the continent once had a much warmer climate.
The sea-water which surrounds Antarctica is called the Antarctic Convergence. These waters are formed by the mixing of the southern waters of the Atlantic, Pacific and Indian oceans.
The sea-water of the Antarctic Convergence is cold and much of it freezes over during the Antarctic winter. In the summer months, however, the continual sunlight penetrates below the surface of the sea and the numbers of phytoplankton greatly increase. The phytoplankton is the producer in most of the Antarctic food chains. The phytoplankton is fed upon by krill, which are small shrimp-like animals.
As the numbers of krill increase, so the secondary consumers are able to feast on them. The great baleen whales, squid and some species of penguins feed entirely on krill.
The continent of Antarctica was practically untouched by human activities until the end of the nineteenth century. Sadly, during the twentieth century, humans have left their mark on the continent. Whalers killed so many whales that many species were almost hunted to extinction. Recently laws have been passed to protect the whales in certain parts of the Antarctic Convergence.
Other ships come to Antarctic waters to fish for krill. The Japanese are particularly fond of krill and large "factory" ships remove vast quantities from the ocean. As the amount of krill decreases so all of the animals linked in the food web suffer.
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