What is the Great Barrier Reef?

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The Great Barrier Reef is the longest coral reef in the world. It measures about 2000 km from end to end. The reef stands in the sea off the north-east coast of Australia. It is built of hard lime stone and most of it is produced by millions of tiny soft-bodied creatures called coral polyps. Most of the top of the reef lies just beneath the water and is a danger to ships. There are 10 safe passages where the ships can sail through. More than 340 varieties of coral have been identified on the reef. They display an astonishing array of colours and are home to a variety offish and other sea creatures. Part of the reef has been destroyed by crown-of-thorns starfish which feeds on the little reef builders.

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