A coral reef is a ridge or mound built of the skeletal
remains of generations of coral animals, upon
which grow living coral polyps. Reefs typically
grow in shallow, clear waters of tropical oceans.
The Great Barrier Reef, in the Coral Sea off the
north-east Australian coast is, at over 2,600 km
long, the world’s largest living reef, and indeed
the largest living organic feature. It comprises
more than 3,000 individual reefs and hundreds
of small coral islands, ranging in size from about
10 ha to 10,000 ha, formed along the edge of the
continental shelf.