> GREAT BARRIER REEF

. In the Coral Sea, between the Tropic of Capricorn and the equator, lies the Great Barrier Reef, one of the great natural wonders of the world. A barrier reef is a long, narrow, mostly submerged coral formation that lies parallel to the shoreline of a landmass. The Great Barrier Reef, which lies off the coast of Queensland in northeastern Australia, is the largest coral reef in the world. It stretches some 1,250 miles (2,000 kilometers) from north to south, a length comparable to the Pacific coast of the United States. Its area is 80,000 square miles (207,000 square kilometers).

A reef is composed of the skeletal remains of millions of tiny corals. A coral is a type of invertebrate, or animal without a backbone. Corals support their soft bodies within hollow "shells" of bonelike material made of calcium carbonate. When a coral dies, its shell remains, and other corals grow upon it. Over millions of years mounds of remains become covered with simple organisms such as algae and plankton, underwater plants, and debris from the ocean. In time an environmental habitat is created that supports many types of higher forms of life, each occupying a specific niche, or relationship to other organisms in the reef community.

The Great Barrier Reef was built upon a shallow fringe of continental shelf in waters warm enough for the coral to flourish. The abundance of sea life on and around the Great Barrier Reef is extraordinary. Besides corals, other forms of invertebrate reef life include anemones, worms, snails, lobsters, crayfish, prawns, jellyfish, and giant clams. Animals having backbones, the vertebrates, include a great number of sea birds and more than 1,500 species of saltwater fishes. Many of the small fishes have brilliant colors and unusual shapes. Although animal life is varied, plant life above the surface of the water is limited, consisting only of about 30 to 40 species.

The irregularities of the seafloor immediately surrounding the reef make commercial netting of fish difficult, so fishing is carried out on a limited basis. Sea turtles that were once captured for food are now protected by law from commercial exploitation.

The pearl-shell industry, for making mother-of-pearl, and scallop collecting are still undertaken by some of the islanders to the north. The Great Barrier Reef's abundance of sea life is a major tourist attraction for Australia. Big game fishing is done in the open waters nearby.

The Great Barrier Reef first became known to the Western world through the explorations of Captain James Cook in the 18th century. In 1770 his ship the Endeavour ran aground on a reef 20 miles (32 kilometers) from land (see Cook). Exploration of the reef, begun by Cook, continued throughout the 19th century. In 1928-29 a scientific survey called the Great Barrier Reef Expedition extensively studied coral physiology and the ecology of the reefs. A modern laboratory for further study of the plants and animals of the Great Barrier Reef was set up on Heron Island in 1951. (See also Coral.)

From: Compton's Interactive Encyclopedia