Coral Reefs

Coral Reefs

Introduction Earth's tropical oceans contain places of wonder and beauty known as coral reefs. These huge undersea communities are home to thousands of living things. Day and night, animals hunt, eat, and avoid being eaten. They depend on each other for food, shelter, and safety. Almost one-fourth of all ocean plants and animals live around coral reefs. Fish, sea turtles, sea stars, and many other animals make reefs their home. Visitors include seabirds and dolphins.

What Is Coral? At first glance, coral may look like oddly shaped rocks or plants. Corals are actually tiny animals called polyps (PAH-lips). Most polyps are smaller than a pea. One branch or mound of coral can have thousands of polyps. Each polyp has a tubelike body and a mouth with tiny tentacles. Polyps are eating machines. At night, they open their tentacles to catch tiny animals. Hundreds of kinds of corals live in the ocean. Most are one of two kinds. Hard corals, also known as stony corals, form hard skeletons. Over time, many millions of these hard skeletons build up and form reefs.

Most stony corals live together with algae (AL-jee). Algae are simple cousins of plants. They supply food for the corals and for many reef fish. Soft corals can bend with the currents. They often look like trees, bushes, or other plants. Algae live in the bodies of some, but not all, soft corals.

A Busy Underwater Community Most people think of brightly colored fish when they think about coral reefs-and with good reason. Thousands of kinds of fish live on reefs. The reefs provide them with food. Reefs also protect them from animals that hunt them for food. Shrimp, lobsters, and crabs also find food at reefs. Sea stars catch small animals that hide among the coral branches. Sea anemones, which look like flowers, wait for their next meal to drift past.

Coral reefs support thousands of kinds of living things. They are important in other ways, too. Reefs help protect coasts from storms and floods. By keeping soil in place, they protect coasts from erosion. Coral reefs also feed and shelter animals that provide much of the world's seafood. They help many countries bring in money and have food to eat. Also, reef plants and animals are used in medicines.