; phylum Cnidaria)
A class of exclusively polypoid, marine cnidarians that are solitary or colonial, and usually sedentary. The oral end is expanded as an oral disc with a central mouth, with one or more rings of hollow tentacles. A well-developed stomodaeum leads from the mouth to a gastrovascular cavity, generally with one or two vertical grooves. The gastrovascular cavity is partitioned into compartments by complete or incomplete mesenteries, some bearing endodermal gonads. Anthozoans first appeared in the Ordovician.
Subjects: Earth Sciences and Geography — Zoology and Animal Sciences.