Coral Reefs - International Reading Association

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Octocoral Corals are related to jellyfish. Their bodies are water-filled sacs. They have a mouth surrounded by stinging tentacles. Unlike jellyfish, though, adult corals do not move around. Instead, they build cup-shaped skeletons to protect their soft bodies. Reefbuilding corals live in large groups called colonies. A single colony can contain thousands of individual animals, called polyps. Different species of coral grow in different patterns, forming the variety of shapes on the reef. The colonies grow larger as some polyps die off and leave their skeletons behind. New polyps then create skeletons on top of the old ones. Large reef-building colonies may grow less than one inch per year. Coral polyps use their stinging tentacles to catch tiny organisms that float by. They have another important source of food, too, though. Coral polyps have algae living in their bodies. The algae can use the sun’s light to create energy, just like plants. In return for nutrients and a safe place to live, the algae give the polyp oxygen and nutrients that it needs. Algae can provide a coral polyp with more than half of its energy. The algae also give the coral its beautiful colors. Most corals must live in shallow, clear water so that the algae can get enough sunlight. Elkhorn Coral Pink Coral C O R A L R E E F S | 2
Coral reefs are important for many reasons. They support a huge diversity of life. Though they cover less than one percent of the ocean floor, they are home to about 25 percent of ocean species. That’s more than a million different species! Humans rely on reefs, too. Reefs are home to fish that people eat. Reefs also protect beaches and coastal communities from pounding ocean waves during storms. They provide income for many people through the tourism they create. Unfortunately, coral reefs are in danger. Careless divers, people who collect coral, and poor fishing practices all damage reefs directly. Pollution from coastal developments and fuel from boats are large problems, too. They can poison the coral and make the water cloudy. In cloudy water, the algae living in the coral can’t get enough sunlight. C O R A L R E E F S | 3
Page 1: y Joanna Solins Types of Coral Reef

Coral Reefs - International Reading Association

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