ABSTRACT
The corals and their associated organisms generate much of the food on which the variety of other reef animals depend, and the corals by means of their varied and complex forms provide the wealth of hiding places essential for the sustained survival of most of the other animals. Besides the corals themselves, the simple plants called algae, the sponges, and a great variety of other invertebrates, as well as fish, are of critical importance. The main coral-reef areas of the world, in addition to the Red Sea, are those lying north-east of Australia and the adjacent islands, the islands of the West Pacific, the East Indies, East Africa and the islands of the Indian Ocean, and the Caribbean. Some corals form large rounded colonies with solid skeletons, these are termed massive corals. Where conditions are appropriate the mounds of coral on our underwater scene will continue to grow until they begin to resemble the characteristic patch reef.
