Class of coelenterates with two phases, sessile hydroids and medusa, generally occurring as different stages of the life cycle.
The following taxa of this class occur in the region:
Order Hydroida (Hydroids)
Order Milliporina (Fire corals)
Order Stylasterina (Lace corals)
Millepora alcicornis (Branching fire coral)
Millepora complanata (Blade fire coral)
Millepora squarrosa (Box fire coral)
Stylaster roseus (Rose lace-coral)