Corals to anemones: polyp forms of Phyllum Cnidaria

A wide range of animals are conoted by the word coral. The most recognizable corals are those responsible for building coral reefs. These are the hermatypic corals. They produce external structures of calcium carbonate that forms limestone after the corals have died. Some kinds of corals are soft externally but may have a carbonate skeleton or a protein-based internal structure to provide some rigidity. In general corals are members of the phylum Cnidaria also known as the Coelenterata that have a dominant polyp life stage. Polyps can be large enough to be easily seen (cup corals) wheras others are quite small and difficult ot see without magnification (hydrocorals). Anemones are polyps (that can get quite large) without hard structures.