Great Barrier Reef

World’s largest grouping of reefs

Executive summary by darmansjah

AUSTRALIA Stretching for 1,250 miles (2,012 km) along the coast of Queensland, Australia, the Great Barrier Reef is the world’s largest grouping of coral reefs. At least 2,900 individual reefs, along with some 300 islets and 600 continental islands, are sprinkled across an area of ocean larger than Great Britain.

This massive reef is all made of and by tiny, simple organisms. Coral polyps are tentacle animals with protective limestone skeletons. Dead corals build up over millions of generations into reefs. Only the colorful, topmost layer is alive. The 400 coral species of the Great Barrier Reef underpin an ecosystem that includes at least 1,500 species of fish, 4,000 species of mollusks, and 240 species of birds.

LIVING COLOR A rainbow of coral greets a diving marine scientist on the Great Barrier Reef. Living coral animals make up only the top layer of the reef; beneath them are millions of years’ worth of skeletal coral remains.

INFINITE VARIETY The reef is home to the quick and the dead, including shipwrecks, crescent-tailed bigeyes, humphead warsse, and broccoli coral.