Hard Corals

Scleractinia – Wikipedia, the free encyclopedia

Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian. Much of the framework of coral reefs is formed by scleractinians.

There are two groups of Scleractinia:

• Colonial corals found in clear, shallow tropical waters; they are the world’s primary reef-builders.
• Solitary corals are found in all regions of the oceans and do not build reefs. Some live in temperate, polar waters, or below the photic zone down to 6000 meters.