Anthozoa

Anthozoa Temporal range: late Ediacaran to present
Stony corals
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Anthozoa
Subclasses
Ceriantharia Hexacorallia Octocorallia

Anthozoa are a class in the phylum Cnidaria. It includes the sea anemones and the corals. It is a monophyletic clade, one of two in the Cnidaria. The other is the Medusozoa.

The class does not have a medusa larval stage in its development, unlike the rest of the phylum. Like all Cnidaria, their food-catching and defense are done by nematocysts, which are extremely effective stinging cells. Over 6,100 species have been described.

There are three subclasses:

• Ceriantharia: the tube-dwelling anemones or cerianthids
• Hexacorallia: 4,300 species of colonial polyps, usually with 6-fold symmetry. This includes all of the stony corals, which are vital for coral reef formation, and all sea anemones, and zoanthids.
• Octocorallia: 3,000 species of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fans and sea whips).

References