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Marine Places

Great Barrier Reef

Australia’s Great Barrier Reef, which stretches 1,250 miles (2,010 km), is the world’s largest coral reef system. Often described as the largest structure ever made by living organisms, it in fact consists of some 3,000 individual reefs and small coral islands. Its outer edge ranges from 18 to 155 miles (30 to 250 km) from the mainland, and its biological diversity is high. The reef contains about 350 species of stony coral and many of soft coral. Its 1,500 species of fish range from gobies, the smallest fish on the reef, and 45 species of butterflyfish, to several shark species, including silvertip, hammerhead, and whale sharks. The reef is also home to 500 species of algae, 20 species of sea snakes, and 4,000 species of mollusks. Damage to the reef over the past 30 years has resulted mainly from predation by the crown-of-thorns starfish and a mass coral bleaching event in 1998. In 1975, the Great Barrier Reef Marine Park was established, and in 1981 it was declared a UNESCO World Heritage site.

The world’s smallest vertebrate?

One of the tiniest residents of the Great Barrier Reef, at less than in (just 7–8 mm) long from snout to tail, is the stout infantfish. When discovered in 2004, the infantfish was declared to be the world’s smallest vertebrate species. That title has since been claimed for a slightly shorter species of Indonesian cyprinid. However, the infantfish is more slender and lighter than the cyprinid.

Great Barrier Reefzoom image
  • Pacific Ocean Southwest
  • Type Barrier reef
  • Area 14,300 square miles (37,000 square km)
  • Condition Damaged by crown-of-thorns starfish; coral bleaching
  • Location Parallel to Queensland coast, northeastern Australia
Great Barrier Reef habitat mapzoom image