Soft Coral
Soft coral, also known as Alcyonacea and ahermatypic coral, do not produce a rigid calcium carbonate skeleton and do not form reefs, though they may be present in a reef ecosystem. Soft corals, such as sea fans, appear to be colorful underwater plants, bending and swaying with the ocean waves.
- Anatomic structures such as tentacles and mesenteries are found in sets of eight, so soft corals are often called octocorals.
- Soft corals are also mostly colonial; what appears to be a single large organism is actually a colony of individual polyps combined to form a larger structure.
- They contain spiny skeletal elements called sclerites in the cells on the outside of the colony. Sclerites are made of protein and calcium carbonate and give soft coral support to allow them to achieve their vertical structures. The sclerites also give their surfaces a spiky or grainy texture.