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Coral reefs are found around nearly all of the islands in the South Pacific. If you live near the sea you can often see waves breaking some distance from the shore. This is the edge of the reef. Coral reefs are built of animals and plants. The animals are called polyps. These polyps are shaped like a cylinder and can be less than 1mm across, but some are 20cm or more in diameter. Each polyp has many tiny arms called tentacles. These arms wave around in the sea water and catch tiny animals which the polyp uses as food. Most polyps feed at night, so during the day they pull in their tentacles out of sight. But even when this happens, tiny plants living inside the polyps use sunlight to make food. Some of th is food is passed on to the polyps and helps them to survive. Because the polyps which make up corals can live only in warm water, we only find coral reefs in the tropical seas. They are never found in colder seas, where the water temperature is less than 18°C. |
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