The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres over an area of approximately 344,400 square kilometres.
Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals.
Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria.
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The reef is located in the Coral Sea, off the coast of Queensland, Australia.
Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands.
The Coral Sea is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion.
Great Barrier Reef, Australia by Queensland, Australia
The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms.
Outer space, deep space, or just space, is the void that exists between celestial bodies, including the Earth.
This reef structure is composed of and built by billions of tiny organisms, known as coral polyps.
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa.
It supports a wide diversity of life and was selected as a World Heritage Site in 1981.
A World Heritage Site is a landmark which has been officially recognized by the United Nations, specifically by the United Nations Educational, Scientific and Cultural Organization.
CNN labelled it one of the seven natural wonders of the world.
The Cable News Network is an American basic cable and satellite television channel that is owned by the Turner Broadcasting System division of Time Warner.
The Queensland National Trust named it a state icon of Queensland.
A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as fishing and tourism.
The Great Barrier Reef Marine Park protects a large part of Australia's Great Barrier Reef from damaging activities.
Other environmental pressures on the reef and its ecosystem include runoff, climate change accompanied by mass coral bleaching, and cyclic population outbreaks of the crown-of-thorns starfish.
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.
The crown-of-thorns starfish, Acanthaster planci, is a large, multiple-armed starfish that usually preys upon hard, or stony, coral polyps.
Coral bleaching is the loss of endosymbiotic algae from the coral, either through expulsion or loss of algal pigmentation.
According to a study published in October 2012 by the Proceedings of the National Academy of Sciences, the reef has lost more than half its coral cover since 1985.
Proceedings of the National Academy of Sciences of the United States of America is the official scientific journal of the National Academy of Sciences, published since 1915.
The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander peoples, and is an important part of local groups' cultures and spirituality.
Aboriginal Australians are legally defined as people who are members "of the Aboriginal race of Australia".
The Torres Strait is a strait which lies between Australia and the Melanesian island of New Guinea.
The reef is a very popular destination for tourists, especially in the Whitsunday Islands and Cairns regions.
The Whitsunday Islands is a collection of continental islands of various sizes off the central coast of Queensland, Australia, approximately 1,400 kilometres north of Brisbane.
Cairns is a major city on the east coast of Far North Queensland in Australia.
Tourism is an important economic activity for the region, generating over AUD$3 billion per year.
Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours.
In November 2014, Google launched Google Underwater Street View in 3D of the Great Barrier Reef.
A March 2016 report stated that coral bleaching was more widespread than previously thought, seriously affecting the northern parts of the reef as a result of warming ocean temperatures.
In October 2016, Outside published an obituary for the reef; the article was criticized for being premature and hindering efforts to bolster the resilience of the reef.
In March 2017, the journal Nature published a paper showing that huge sections of a 500-mile stretch in the northern part of the reef had died in the course of 2016 due to high water temperatures, an event that the authors put down to the effects of global climate change.