Classes of Cnidaria

	Class Hydrozoa	Class Scyphozoa	Class Cubozoa	Class Anthozoa
life cycle stages	polyp only; medusae only or polyp and medusae	polyps and medusae; medusa stage dominant	polyps and medusae; medusa stage dominant	polyp only
gastrovascular cavity	not divided by septa	4 septa; 4 gastric pouches plus stomach		6 or 8 septa or multiples of 6 or 8

	Hydrozoan Medusae	Scyphozoan Medusae
velum	present	absent
rhopalia (sensory)	absent	present
manubrium	usually rounded	usually square of rectangular
bell margin	continuous	notched
oral arms	absent or poorly developed	present, usually well-developed