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The area abounds with wildlife, including dugong and green turtles, varieties of dolphins and whales, more than 1500 species of fish, 4000 types of mollusc and more than 200 species of birdlife. The Great Barrier Reef system consists of more than 3000 reefs which range in size from 1 hectare to over 10,000 hectares in area. The reef is scattered with beautiful islands and idyllic coral cays and covers more than 300,000 square kilometres.
The corals which make up the various reefs and cays, and which are the base for this variety of sea and animal life, consist of individual coral polyps - tiny live creatures which join together to form colonies. Each polyp is a tiny jelly-like blob crowned by tentacles, and looks not unlike an anemone, but much smaller. Each polyp lives inside a shell of aragonite, a type of calcium carbonate which is the hard shell we recognise as coral. The polyps join together to create forests of coloured coral in interesting fan, antler, brain and plate shapes.
There are many different types of coral, some are slow growing and live to be hundreds of years old, others are faster growing. The colours of coral are created by algae. Only live coral is coloured. Dead coral is white. The ideal environment for coral is shallow warm water where there is a lot of water movement, plenty of light, where the water is salty and low in nutrients. Reefs are sensitive to climate change, to changes in patterns of water movement, and to physical damage - so problems like global warming, El Nino, the building of moorings or breakwaters, any additional nutrients running off land from human habitation, may well have a negative effect on the reef system, and thus on the sea and land animals which depend upon it for survival.
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