Differences in Reef Types

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There are three main types of reefs; fringing reefs, barrier reefs, and atoll reefs. Fringing reefs are the most common of the three as they grow directly from shore, surrounding the islands like borders along the shoreline. When a fringing reef continues to grow upwards from a volcano island that has sunken entirely below sea level, an atoll is formed. Atoll reefs are circular/oval shaped and has an open lagoon in its center. Barrier reefs are quite similar to fringing reefs as they also border a shoreline, but what makes it different to a fringing reef is that they don’t grow directly from the shore, but are separated from land by an expanse of deep water. This creates a lagoon of deep water between the shore and the reefs. Hard corals or stony corals are primary reef building/hermatypic corals that have rigid skeletons made of calcium carbonate (CaCo3), which in crystal form is know as aragonite. Colonies of hard corals have many polyps cemented together by the calcium carbonate skeletons they create, and a layer of tissue covers the skeleton and connects coral polyps for distr...

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