1. Coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
   - class Hydrozoa

1. Colonial coelenterates having the polyp phase dominant
   "Portuguese man-of-war is a well-known hydrozoan";
   - hydroid

Type of: class, cnidarian, coelenterate

Part of: Cnidaria, Coelenterata, phylum Cnidaria, phylum Coelenterata

Encyclopedia: Hydrozoa