Great Barrier Reef facts for kids
| UNESCO World Heritage Site | |
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Image of part of the Great Barrier Reef adjacent to Queensland, taken from the International Space Station
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| Location | Off the east coast of the Queensland mainland, Australia |
| Criteria | Natural: vii, viii, ix, x |
| Inscription | 1981 (5th Session) |
| Area | 34,870,000 ha (86,200,000 acres) |
 Locator map of the protected area |
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The Great Barrier Reef is the world's largest coral reef located in the Coral Sea, off the coast of Queensland, Australia. It is made up of more than 2,900 separate reefs and 900 islands. It is so huge you can even see it from space!
This amazing natural wonder stretches for over 2,300 kilometers (1,400 miles) and covers about 344,400 square kilometers (133,000 square miles). It is the largest structure made by living things.
Coral polyps are small, soft-bodied creatures, and they're the master builders of the reef. Each polyp is like a tiny tube with a mouth at the top, surrounded by tentacles. These tentacles help them catch tiny bits of food floating in the water.
But here's the cool part: coral polyps can build a hard, protective skeleton around themselves using minerals from the seawater. These skeletons are made of calcium carbonate, which is the same stuff that makes up chalk and limestone.
As the polyps grow and multiply, they build more and more of these skeletons. Over thousands of years, these skeletons accumulate and form the massive structures we know as coral reefs.
The Great Barrier Reef is home to an amazing variety of sea creatures. Because of its unique importance, it was recognized as a World Heritage Site in 1981. In 1997, CNN called it one of the Seven Natural Wonders of the World.
The biggest threat to the Great Barrier Reef today is coral bleaching caused by high sea water temperatures as a result of global warming. Studies have shown that the reef has lost more than half of its coral since 1985. A 2020 study confirmed that over half of the coral cover was lost between 1995 and 2017.
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Discovering and Naming the Great Barrier Reef
The Great Barrier Reef has been known and used by the Aboriginal Australian and Torres Strait Islander peoples for a very long time. It is a special part of their cultures and spiritual stories.
The first European to see the Great Barrier Reef was James Cook in 1770. He was sailing and mapping the east coast of Australia. On June 11, 1770, Cook's ship, the HMS Endeavour, got stuck on a shallow part of the reef. It took seven weeks to repair the ship!
Later, Matthew Flinders gave the reef its famous name after he mapped it in more detail in 1802. He used terms like "great reef" and "barrier reef" to describe the many reefs that protect the coast from the open sea.
How was it formed?
Scientists believe that about 24 million years ago, as Australia moved into warmer, tropical waters, corals started to appear. During the last Ice Age, the sea levels were much lower than they are today. As the Earth started to warm up, the ice melted, and the sea levels rose. This flooded the coastal areas and provided the perfect conditions for coral polyps to thrive. Scientists have found coral "skeletons" that are half a million years old. The living reef we see today started growing on these older platforms about 9,000 years ago.
The rising sea levels allowed the coral polyps to spread and build their reefs on the submerged land. Over time, the reefs grew upwards and outwards, creating the vast and complex system that we see today.
Different Reef Shapes
The Great Barrier Reef is divided into many different areas. You can find different types of reefs here:
- Fringing reefs are common in the southern part, growing close to islands like the Whitsunday Islands.
- Lagoonal reefs have a calm, shallow area in the middle.
- Crescentic reefs are shaped like a crescent moon and are common in the middle of the reef system.
- Planar reefs are flat and wide. Many of the reef's islands are found on these reefs.
Navigating through the reef can be tricky. Many ships have been lost here over the centuries. Explorers like James Cook and Matthew Flinders helped map the area, making it safer for ships.
Rainbow of colors
One of the most amazing things about the Great Barrier Reef is its incredible colors. Corals come in all sorts of shades, from bright pinks and purples to vibrant yellows and greens.
But where do these colors come from? Corals have a special relationship with tiny algae called zooxanthellae (say: zoo-zan-THEL-ee). These algae live inside the coral tissues and provide the coral with food through photosynthesis, just like plants do on land. In return, the coral provides the algae with a safe place to live.
The zooxanthellae are also responsible for the corals' vibrant colors. Different types of algae produce different pigments, which give the corals their unique hues.
Ecology
The Great Barrier Reef has 1,500 species of fish, and many other animals, algae, and corals. This includes many vulnerable or endangered species. Some of these exist only on this reef system.
Mammals
Thirty species of whales, dolphins, and porpoises have been seen in the Great Barrier Reef. This includes the dwarf minke whale, Indo-Pacific humpback dolphin, and the humpback whale. Most of the population of the dugongs live there.
Turtles and Dugongs
Six species of sea turtles come to the reef to breed. These are the green sea turtle, leatherback sea turtle, hawksbill turtle, loggerhead sea turtle, flatback turtle, and the olive ridley. There are two different groups of green sea turtles on the Great Barrier Reef. One group lives in the northern part of the reef and the other in the south. Fifteen species of seagrass attract the dugongs and turtles. They also provide a food and shelter for fish. The most common kinds of seagrasses are Halophila and Halodule.
Other sea animals
Saltwater Crocodiles live in mangrove and salt marshes on the coast near the reef. No crocodile nests have been found on the reef. The salt water crocodiles on the reef travel long distances. There are not many living around the reef. Around 125 species of shark, stingray, skates or chimaera live on the reef. About 5,000 species of mollusc live on the reef. These include the giant clam, nudibranchs and cone snails. Forty-nine species of pipefish and nine species of seahorse have been found. Seven species of frogs live on the islands.Also, the Moray eel lives on the bottom, preying on fish.
Birds
215 species of birds come to the reef or nest or roost on the islands. This includes 22 species of seabirds and 32 species of shorebirds. These include the white-bellied sea eagle and roseate tern. Most nesting sites are on islands in the northern and southern regions of the Great Barrier Reef. About 1.7 million birds use the sites to breed.
Plants
The islands of the Great Barrier Reef have 2,195 known plant species. Three of these do not live anywhere else. The northern islands have 300-350 plants which are woody. The southern islands have 200 plants which are herbaceous. The Whitsunday region has the most plant species placing at 1,141. The plant species are mostly spread by fish
Sea snakes
Seventeen types of sea snake live on the Great Barrier Reef. They take about 4 years to become old enough to breed. They usually live on the sea floor. They live in warm waters up to 50 metres (160 ft) deep. They are more common in the southern part of the reef.
Fish, ascidians and bryozoans
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More than 1,500 species of fish live on the reef. These include the clownfish, red bass, red-throat emperor, and several types of snapper and coral trout. There are at least 330 species of sea squirts (ascidians) on the reef. These vary in size from 1 mm-10 cm in diameter. Between 300-500 species of bryozoans live on the reef system. These are small water animals that look like moss, or branches.
Corals
Four hundred species of corals, both hard corals and soft corals live on the reef. Most of these spawn, releasing thousands of eggs, in huge events. This spawning is controlled by the rising sea temperatures. This happens in spring, summer and some parts of autumn, as part of the moons lunar cycle, and the day/night diurnal cycle. Reefs in the inner Great Barrier Reef spawn during the week after the full moon in October. Outer reefs spawn in November and December. The common soft corals on the Great Barrier Reef belong to 36 different types. Five hundred species of marine algae or seaweed live on the reef. This includes thirteen types of Halimeda. These deposit chalky (calcareous) mounds up to 100 metres wide. They have mini-ecosystems on their surface which have been compared to rainforest cover.
Climate change
A new report, the Reef Outlook Report, says that climate change will cause huge damage to the reef. The report was written by the Great Barrier Reef Marine Park Authority. Warmer and more acidic water around the coral reef will slow down calcification, which is how the coral grows and becomes strong. The corals will become bleached (lose their colours) and many species that live on and around the reef will be in danger. The Australian government has already spent AU$ 325 million to improve the health of the reef in the last two years.
Other dangers
The Reef Outlook Report also warned of other dangers to the reef. These included poor quality water running into the sea from the mainland. This water is polluted with farm insecticides and rubbish from nearby towns. The increasing amount of development on the coast is destroying natural marine and coastal habitats. There is also some damage from fishing.
Fun facts about the Great Barrier Reef
- The Great Barrier Reef is bigger than Italy, Japan, or Germany.
- It's home to over 30 species of whales, dolphins, and porpoises.
- Some of the coral in the reef is over 8,000 years old!
- It was Matthew Flinders who named the Great Barrier Reef, after his more detailed mapping of it in 1802.
- The Reef Research Center has found the remains of coral that are half a million years old. Corals have been growing in the region for as long as 25 million years.
Related pages
Images for kids
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Aerial photography
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The Great Barrier Reef is clearly visible from aircraft flying over it
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Heron Island, a coral cay in the southern Great Barrier Reef
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Aerial view of Arlington Reef
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Moore Reef
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A striped surgeonfish amongst the coral on Flynn Reef
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The Shen Neng 1 aground on the Great Barrier Reef, 5 April 2010
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A blue starfish (Linckia laevigata) resting on hard Acropora and Porites corals
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A scuba diver looking at a giant clam on the Great Barrier Reef
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Helicopter view of the reef and boats
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See also
In Spanish: Gran Barrera de Coral para niños
