coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
Main Entry: Hy·dro·zoa Pronunciation: "hI-dr&-'zO-& Function: noun plural : a class of coelenterates that includes various simple andcompound polyps and jellyfishes having no stomodeum or gastric tentacles
