reefs are scattered throughout the tropical and subtropical
western Atlantic and Indo-Pacific oceans. About 600,000
km2 (231,600 mi2) of coral reefs
are known to exist, comprising 0.17% of the ocean's
surface. The Great Barrier Reef off northeastern Australia
in the Indo-Pacific is the largest barrier reef in the
world, stretching more than 2,000 km (1,240 miles).
are built by vast colonies of coral polyps - tiny invertebrate
animals related to sea anemones and jellyfishes. Reef-building
corals secrete calcium carbonate skeletons. The calcium
carbonate gradually accumulates and the reef becomes
reefs are one of the most biologically diverse ecosystems,
rivaling rain forests for the number of species inhabiting
them. About 6,000 to 8,000 fish species as well as sponges,
sea anemones, bryozoans, worms, sea stars, crustaceans,
and snails live on coral reefs.
addition to the array of marine life they support, reefs
also protect coastlines from erosion, provide food and
recreation for people, and are proving to be a new frontier
for medical research. Unfortunately, reefs are threatened
worldwide by pollution, development, and coral harvesting.
More than one-third of all coral reefs have already
been destroyed or permanently damaged.
strengthen efforts for coral reef management and conservation,
the U.S. Departments of State and Commerce joined with
nations around the globe and declared 1997 the International
Year of the Reef. You can help protect reefs by not
purchasing coral or other living souvenirs and by keeping
the ocean clean. If you plan to visit a coral reef,
learn how to safely enjoy this living system.
More information about
Corals and Coral Reefs