What type of coral reefs exist?

People are fairly familiar with coral reefs; however most of them don't realize that there are actually several different types of reef. If you are going to learn about coral reefs it is important to know about the different kinds and how they develop. The differences between the reefs are based almost entirely on how they are created. Therefore you can learn a lot about the local area by looking at what kind of reefs exist.

There are basically four different types of coral reefs; the distinction between the types is usually determined by the size and shape of the reef. The first type which is also the most common is the fringing reef. This is the type that is usually associated with very small islands. The coral reef surrounds the island and is located very close to land. This normally forms a small lagoon between the island and the reef. This type of reef is important because it protects the small islands from the impact of the waves which would destroy it if the reef were not there.

The next most common type of reef is a barrier reef. In reality this is simply a very large fringing reef. These are located further from shore and they extend for much longer distances. They also tend to naturally surround larger pieces of land. In most cases a barrier reef will be several hundred meters from the shore and extend for hundreds if not thousands of kilometers. Far and away the most famous, as well as largest, barrier reef is the Great Barrier Reef around Australia. It extends for more than two thousand kilometers.

The next type of reef is an atoll, most people are familiar with the term but aren't really sure what it means. In this case the reef appears to encircle nothing but a lagoon. In reality what has happened is that the island has sunk and the only thing that is left is the reef. In almost all cases an atoll will be circular or horse shoe in shape. There are some atolls where the coral is so big and extends far enough above the surface of the water that people actually live on it.

The last type of coral reef is a patch reef; this is just what it sounds like it is a patch of reef that does not encircle an island. In the vast majority of cases you will find patch reefs located in the lagoon formed by one of the other types of reefs. However it is also possible for them to form in other locations. In fact it surprises many people to learn reefs can sometimes form in deep cold water, when this happens it is almost always a patch reef. This is not all that common but patch reefs in places other than the tropics are possible.