Living Coral Coral reefs form only in the warm, shallow waters of tropical oceans. Coral reefs are formed from the skeletons of coral animals.
Formation of Coral Reef Coral animals absorb the element calcium from the ocean water. –Calcium changes into calcite and forms their skeleton. –When animals die, their skeletons remain and coral is built on top of them.
Three Types of Coral Reefs Fringing reefs –Close to shore Barrier reefs –Lies at least 10 km from land Atolls –Ring-shaped coral island far away from land –Develops when coral grows on top of a volcanic island that’s beneath the ocean’s surface
Limestone Deposits A coral reef is organic limestone. Over time, coral buried by sediments. Limestone that began as coral found in continents in places where uplift has raised ancient sea floors above sea level.