Longest reef

The Great Barrier Reef off Queensland, north-eastern Australia, is approximately 2,300 km (1,430 miles) in length. Its entire span comprise a chain of some 3,000 smaller reefs and around 900 islands.

As coral reefs are made up of millions of living polyps (small soft-bodied colonial animals related to sea anemones and jellyfish) and their hard calcium-carbonate skeletons, this also makes the Great Barrier Reef the largest animal structure on Earth.

On three occasions, between 1962 and 1971, 1979 and 1991 and between 1995 and the present, corals on large areas of the central section of the reef have been devastated by the crown-of-thorns starfish (Acanthaster planci)