Marine Biology

Major types of coral reefs

There are three major types of reefs: fringing reefs, barrier reefs and atolls. Fringing reefs extend along the shoreline, close to land or separated only by a narrow stretch of water, but that can extend out to sea long distances. This reef type exists in shallow waters. Barrier reefs form farther offshore, usually 10-100 kilometers from the coast, and often form massive walls of coral separated from the coast by a large channel or lagoon. Atolls are circular reefs surrounding a lagoon that form when volcanic islands sink into the ocean over millions of years.