The Great Barrier Reef

• The last Ice Age ended 20,000 years ago, by 10,000 years ago the sea began to flood back over the continental shelf. Sea level reached its present state 6,000 years ago.
  
  
• The Great Barrier Reef is around 18 million years of age in the north and 2 million Years old in the south, with the existing reef system being between 10,000 and 6000 years old.
  
  
• The Great Barrier Reef with over 2600 individual reefs and about 300 islands, is the largest complex of coral reefs in the world today.
  
  
• The Great Barrier Reef extends for over two thousand kilometres along the North Eastern coastline of Australia covering an area greater than that of Great Britain or Victoria and approximately half the size of Texas. The entire Great Barrier Reef is a multi-use' Marine Park managed by the Great Barrier Reef Marine Park Authority.
  
  
• The Great Barrier Reef contains over 1500 species of fish, 400 species of coral, 4000 species of mollusc and innumerable species of worm, crustacean and echinoderm.
  
  
• The architects of the reef are corals that, with the help of single cell symbiotic algae, living within their tissues, convert dissolved limestone into limestone skeletons. The basic unit of a coral colony is the polyp. Polyps build communal limestone homes to form many complex and beautiful coral colonies. Coralline algae and calcareous sponges bind together the' skeletons of dead coral colonies into solid reefs.
  
  
• Reef building corals need warm waters, light so that the symbiotic algae can photosynthesise and a hard substrate on which to settle. Queensland's coastal waters provide all these necessary conditions for corals to flourish.

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