Coral Reefs

Corals
Corals are structures built on a hard surface and found in oceans and lagoons. Many people think corals grow only in warm waters with plenty of sunlight. But some coral species also grow in cold, dark waters.

Image of Coral Reef Structrure

Are there different types of coral reef structures?
Yes, there are! The main types of coral reef structures are: the fringing reef, patch reef, barrier reef, atoll and bank or platform reef.

Letís look at each one separately.

Fringing Reef
This type of reef is directly attached to the shore. Fringing reefs grow quickly in shallow water but their growth furtheraway from shore is slower. Fringing reefs have a shallow platform that spreads outward to a sharply defined edge. Imagine the reef like a shelve with an edge that drops down to the sea floor.

Image of Fringing Reef

Patch Reef
Patch reefs communities are found in waters 10-30 feet in depth. The outer edge of each patch reef is surrounded by a ring of sand. It is the feeding fish that determine how wide this sand ring is. If the fish feel safe close to the reef then the sand ring will be narrow. A wide ring of sand means that the feeding fish feel safe further away from the reef. Each patch reef is different in size, development, and species living on them. Mostly large colonies of star and brain corals make up this reef type.

Barrier Reef
Barrier reefs are often some distance from the coast. Some barrier reefs are attached to fringing reefs on shelving coastlines. In other cases these reefs may have developed in offshore places. Sometimes a lagoon separates a barrier reef from the coast.

Image of Barrier Reef

Atoll
An atoll is formed when a reef grows in a pyramid shape, rather like a volcano. A lagoon forms in the center of the surrounding reef and smaller reefs may grow inside this lagoon.

Image of Atoll

Bank or Platform Reef
Bank reefs are found in deeper waters than the patch reefs of near-shore environments at depths 20-60 feet. Bank reefs are significantly larger than patch reefs and are common dive and snorkel destinations. Bank reefs also have high species diversity, meaning many kinds of animals and plants live on and around this type of reef. Bank reefs have something special called spur and groove patterns. The spur and groove formation is made up of low ridges of corals (spurs) separated by sandy bottom channels (grooves). The most commonly found corals are elkhorn, staghorn, seafans, sea whips and brain corals.

Image of Platform Reef

Different Kinds of Coral»