1.3. Coral Formation and Types

Coral reefs begin to form when free-swimming coral larvae attach to submerged rocks or other hard surfaces along the edges of islands or continents. As the corals grow and expand, reefs take on one of three major characteristic structures:

♤ Fringing reefs, which are the most common, project seaward directly from the shore, forming borders along the shoreline and surrounding islands.

♤ Barrier reefs also border shorelines, but at a greater distance. They are separated from their adjacent land mass by a lagoon of open, often deep water.

♤ An atoll forms if a fringing reef forms around a volcanic island that subsides completely below sea level while the coral continues to grow upward. Atolls are usually circular or oval, with a central lagoon.