Multiple Colonization of a Bivalve-Inhabiting Hydroid Eugymnanthea japonica (Leptomedusae : Eirenidae) in Japan

Abstract

Mature medusae of both sexes of Eugymnanthea japonica are released from a total of 30 out of 93 host bivalve specimens of three species collected from eight out of 12 localities sampled in Japan, showing the multiple colonization of this hydroid species. Including the above 30 hosts, 62 hosts harbored female and 61 hosts harbored male, suggesting an equal chance of settlement to the host by either sex if only a very small number of individuals colonize a host.