At over 2,000 kilometers long, The Great Barrier Reef is the largest living structure on Earth

Coral reefs consist of huge numbers of individual coral polyps (soft-bodied, invertebrate animals) that are linked together by tissue. The Great Barrier Reef is an interlinked system of about 3,000 reefs and 900 coral islands divided by narrow passages, located just beneath the surface of the Coral Sea. Spanning more than 2,000 km and covering an area of some 350,000 sq km, it is the largest living structure on Earth and the only one visible from space. However, this fragile coral colony is beginning to crumble, battered by the effects of climate change, pollution, and manmade disasters.