Coral reef to form fringing reefs, and can eventually grow become a barrier reef. Where the bottom is rising, fringing reefs can grow around the coast, but coral raised above sea level dies. If the land subsides slowly, the fringing reefs keep pace by growing upwards on a base of older, dead coral, forming a barrier reef enclosing a lagoon between the reef and the land. A barrier reef can encircle an island, and once the island sinks below sea level a roughly circular atoll of growing coral continues to keep up with the sea level, forming a central lagoon. Barrier reefs
Coral reef fish line speed, so coral reef fish have developed bodies which optimize their ability to dart and change direction. They outwit predators by dodging into fissures in the reef or playing hide and seek around coral heads. Many reef fish, such as butterflyfish and angelfishes, have evolved bodies which are deep and laterally compressed like a pancake. Their pelvic and pectoral fins are designed differently, so they act together with the flattened body to optimise manoeuvrability. Coral reef fishes exhibit a huge variety of dazzling and sometimes bizarre colours and patterns. This is in marked contrasts to open water fishes which