Coral Reefs

Coral reefs are amazing places under the sea. They look like big underwater gardens full of color. But corals are not plants. They are actually tiny animals that live together in huge groups. Coral reefs are home to thousands of different kinds of fish and sea creatures.

How Reefs Are Made

Each tiny coral animal is called a polyp. Polyps build hard shells around themselves from the water. When they die, new corals grow on top of the old shells. Over many years, these shells stack up into huge reefs. Some reefs took thousands of years to grow.

A diagram showing how coral atolls form around islands.
A diagram showing how coral atolls form around islands. (Atoll_forming-i18.jpg: Susan Mayfield and Sara Boore, modified by Eurico Zimbres derivative work: Geronimo20 (talk) / Wikimedia Commons)

Home to Many Animals

Coral reefs are like busy cities in the ocean. Fish, crabs, turtles, octopuses, and sharks all live there. Clownfish, angelfish, and parrotfish swim among the corals. Many reef animals hide in the holes and cracks. Reefs give food and shelter to one quarter of all sea animals.

Fun Facts

  • The Great Barrier Reef is the biggest reef in the world.
  • Coral reefs can be seen from space.
  • Warm water can turn corals white and sick.

Did You Know?

Coral reefs only cover a small part of the ocean floor. But they are home to more kinds of animals than almost anywhere else on Earth.