Chapter 11 The Great Barrier Reef

‘The largest living thing in the world’ – that is how many people describe the Great Barrier Reef. And they are right, because this living thing is more than 2,500 kilometres long – and it is alive. The reef is growing all the time, because of very small sea animals called corals.

Corals are unusual animals, because they make the island that is their home. This island is not made of stone; it is made by the corals from calcium carbonate. Millions of corals together make an island under the water which is called a coral reef. And the Great Barrier Reef is a long line of about 3,000 coral reefs and 900 islands near the north-east of Australia. It is home to thousands of kinds of fish and other sea animals.

Coral reefs are good places to live. There are lots of holes, which are good places for fish to hide, and which are easy to defend. There are many dangerous fish around the reef, but there is

lots of food too. There are not many coral reefs in our seas – less than 1 per cent of our seas have coral reefs in them. But our coral reefs are home to 25 per cent of all things that live in the sea.

And the important thing is this – coral reefs are beautiful places! Corals need seawater, but they also need sunlight. Because of this, corals do not usually live in deep, dark water – they prefer water that is less than 150 metres deep. So the water around a coral reef is warm, and full of light and life. Millions of visitors come to the Great Barrier Reef every year to see the beautiful reefs and sea animals.

Some of the sea animals on the Great Barrier Reef are very rare. One of these is the sea cow

(also called the dugong). Just like cows that live on the land, the sea cow eats grass – but it is a kind of sea grass that grows under the water. It is called a ‘cow’, but there is another land animal that is more like it. Just look at its nose. Yes, it is the elephant!

There are seven kinds of sea turtle in the world, and six of them live on the Great Barrier Reef. The turtle is one of our oldest animals. We know that the first turtles lived more than 200 million years

ago. Turtles can live for as much as eighty years. They need to live for a long time – some mother turtles do not begin to have their babies until they are twenty or even thirty years old!

The Great Barrier Reef is one of the great natural wonders of the world. But, like other coral reefs, it is in danger. One of the dangers is natural: it is an animal called the crown-of-thorns starfish, which eats corals. Is this a big danger? Fifty years ago, we thought it was, but today we are not sure. Some years there are more of these starfish, some years there are fewer. But there are also two dangers that come from people. First, the sea is getting dirtier, and second, it is getting warmer. Both of these things kill coral reefs. And both of these dangers are getting worse. Will people destroy the largest living thing in the world?