Epizoic Anthoathecate Species (Cnidaria, Hydrozoa) Growing on Eroded Shells of Live Gastropods (Nassarius festivus) in Japan

抄録

In addition to polyps of the anthoathecate hydroid Koellikerina bouilloni previously reported exclusively on old, eroded shells of live gastropods (Nassarius festivus) in Ibaraki Prefecture, Japan, the polyps of three additional epizoic anthoathecate hydroid species (Dicoryne conybearei, Stylactaria misakiensis and Leuckartiara sp.) were found on similar condition N. festivus shells in different localities in Japan. Because polyps of these hydroid species were not found on fresh shells, it is suggested that N. festivus could avoid colonization by the hydroids whilst occupying fresh shells, but not older eroded ones, the latter therefore providing a suitable substrate for the hydroid polyps.