The great Barrier Reef - the largest system of coral reefs in the world - is more than 2,000 km in length and comprises 2,900 separate reefs and 940 islands. Its high species diversity includes more than 400 species of coral, 4,000 species of molluscs, 1,500 species of fish, 6 species of turtles, 35 species of seabirds and 23 species of sea mammals, The Great Barrier Reef is one of the richest and most complex natural systems in the world. The Reef's diverse range of habitats all connect and support each other, which means they are all vital to the life of the Great barrier Reef