Hydrozoa Owen, 1843

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 7

Class Hydrozoa Owen, 1843

Hydrozoa Owen, 1843: 82 .

Diagnosis. Medusozoa with acellular mesoglea; polyps lacking a stomodeum (actinopharynx) between coelenteron and mouth; coelenteron lacking gastric filaments, not divided into compartments by mesenteries or septa; medusae craspedote, with velum (craspedon) partially enclosing subumbrellar cavity; gametes usually of ectodermal origin.

Remarks. Owen (1843) established Hydrozoa for “The class of Polypi organized like the Hydra .” For a comprehensive overview of the class, see Bouillon et al. (2006). Updated classifications of the group are given by Daly et al. (2007) and Schuchert (2009). The class Hydrozoa comprises two monophyletic clades, Hydroidolina Collins, 2000 and Trachylina Haeckel, 1879 .