For admirers of exotic lands, a coral reef is the landscape of their dreams. When one thinks of a coral reef, he starts dreaming of sunny beaches with crystal waters. Corals live in the hot seas (mostly in the latitudes of 30 degrees north and south of the Equator where water temperature is somewhere between 18 and 30° C).
A coral reef is constituted of the skeletons of tiny organisms, called polyps. It is these microscopic organisms, which actually grow at a slow pace over the years that develop the reefs. It is estimated that coral reefs cover 0.2% of the area of oceans, and they are the home of many marine species. For countries with coral reefs, like Japan, Egypt and Australia, a coral reef is also a major tourist attraction.
There are several classifications of what a coral reef can be, but the most popular divides them in four groups: fringing reefs, platform reefs, barrier reefs, and atolls. Fringing reefs are usually situated in shallow waters near the shore. They can be separated from the shore by a narrow strip of water, while platform reefs are, on the other hand, pretty far away from the shore and platform reefs are flat.
Barrier reefs are formed parallel to the coastline and are usually separated from it by a lagoon. This type of coral reef is often very big - for instance, the Great Barrier Reef in Australia is over 2,300 kilometers long and its surface covers over 200,000 square kilometers. The last variety in the coral reef enumeration is the atolls. They are circular in form and usually encircle an island. Typically atolls have a lagoon in the middle. Atolls can be deep sea if they rise from the ocean or continental when they are found on the continental shelf.