The Great Barrier Reef
Australia’s Great Barrier Reef is the world’s largest and most complex reef system. It is visible from the moon.
Evolution of the Great Barrier Reef
65 million years ago, the Australian continent formed a part of the land mass called Gondwana, which was located in the cold southern waters. As it broke away and drifted north in tropical waters, a coral reef system started to grow on the continental shelf along the eastern coastline.
The Great Barrier Reef is believed to be over 18 million years old in the north and 2 million years old in the south. Through time, the warming and cooling of the earth together with changes in the size and shape of the sea basins have caused numerous sea level changes. During the last Ice Age (approximately 18 000 years ago) sea levels dropped over 100 metres, turning what is now the Great Barrier Reef into grassy plains and limestone hills. The sea level started to rise 12 000 years ago as the ice caps melted and reached its current level about 8000 years ago. As the sea level rose, those corals that survived in the water off the continental shelf reproduced and started to recolonise the old remnant reefs.
 Great Barrier Reef Map |
Today the Great Barrier Reef stretches more than 2300 kilometres along the northeast coast of Australia comprising of more than 2900 reefs and 940 islands. Covering more than 344 000 square kilometres the Great Barrier Reef Marine Park holds global iconic status and is recognised as a unique area of outstanding value to humankind and a jewel in the crown of the world’s natural wonders.
The Great Barrier Reef provides habitats for a wide variety of marine-based plants and animals. It is home to approximately:
- 1500 species of fish
- 350 species of hard corals
- One-third of the world’s soft corals
- 5000 - 8000 species of molluscs (for example octopus, oysters)
- 1500 species of sponge
- 800 species of echinoderms (for example starfish, sea cucumbers and sea urchins)
- 500 species of seaweed
- More than 30 species of marine mammals
- Six of the world's seven species of marine turtle.
