A reef is an area found at the bottom of an ocean where different kinds of colorful coral, fish, crab, starfish, and many other aquatic animals can be found.
Colorful corals come in various shapes. A coral colony forms from a small larva that settles on a reef. When divers investigate a reef at night, they are delighted to see the bright colors of corals reflecting light from their flashlights. Nighttime is also when corals polyps extend their tentacles to feed on plankton.
Soft corals, like the Dendronespthya, don't have hard skeletons. When removed from the water, they become a very wet. They don't need sunlight, and unlike true corals, they can live in the deeper and darker parts of the reef. Reef sharks also live in deeper, darker areas, and hunt fish after resting in coral caves all day.
There are other strange animals that make up coral reefs, one species being tube worms. These beautiful red worms live in European coastal waters. They can grow so well that they form mini-reefs with hard tubes.
Reefs are not only important for the animals they contain, but they are also important to humans. People living near oceans count on coral reefs for fish, medicine, and other resources. They use carbon dioxide to create their skeletons, which cuts down on carbon in the atmosphere, and prevents global warming.
Reefs are not only beautiful, they are also important, to humans and animals alike.
[Source: Guide to the Oceans: A Thrilling Journey into a Watery World]