Coral reefs are the largest biological and most beautiful structures in the world.There are over 7,000 reefs in over 115 countries. The largest and most popular reef, the Great Barrier Reef is located in Australia. Coral reefs are constructed of algae and skeletons of plants and animals. There are four types of reefs: fringing, barrier, atoll, and patch.

Coral reefs are arguably the world’s most beautiful habitats. Coral reefs have been called the rainforests of the oceans, because of the rich diversity of life they support. Scientists have not yet finished counting the thousands of different species of plants and animals that use or live in the coral reef. They are massive underwater structures formed by the limestone skeletons of tiny invertebrate animals. Reefs house a greater diversity of body forms, chemistry, and animal phyla. Coral animals begin life as free-floating larvae, but settle on the sea floor in sedentary colonies. The term “coral” applies both to these animals and to their skeletons, particularly the skeletons of stone-like corals.

Many different organisms, including mollusks, sponges, and worms, help shape reefs, but hard corals and various algae are the major architects. In effect, the corals build limestone, because their skeletons are made of Calcium Carbonate. The skeletons deposited by these corals and other organisms accumulate, along with sand and other debris, to form the backbone of the reef.