Second Grade
Worksheets
A Coral Reef
A coral reef is a little world all by itself. It is a place of beauty. Why are coral reefs important to us? They are home to one-quarter of the fish in the ocean. What would happen to them if the coral reefs died?
Corals are tiny animals called polyps. There are two kinds of corals. One is hard and the other is soft. Coral polyps have very soft bodies. Hard corals grow layers of calcium to protect themselves. (Calcium is the same mineral that makes the hard shell in hen eggs.) Brain and staghorn corals are examples of hard corals. They are stiff like rocks. Soft corals do not grow that calcium shell. Some examples of soft corals are sea fans or sea whips. They move and sway with the water.
Coral need certain things to grow. They need warm, shallow, clean water. They need warmth and sunlight to live and grow. If the water gets dirty, the dirt will settle on the coral. Coral animals cannot shake off the dirt or move to another place. Dirt cuts them off from food, light, and oxygen.
Mangroves trees and fields of seagrasses are often found between land and coral reefs. They help keep the reefs clean. They trap and filter soil and sediment out of the water. If the corals did not have mangroves and seagrasses, they would die. If the reefs die, many fish would die, too. All the animals and plants depend on each other to live.
Mangrove trees have their roots in salt water. Their branches hold nests for water birds. Their roots trap nutrients and food for birds. Mangrove roots also hold onto the ground. They keep it from washing away into the sea. When mangrove trees are cut, more dirt is lost. More mud can get out into the ocean.
