Importance of host quality in the distribution of the epizoic limpet Hipponix conicus (Caenogastropoda: Hipponicidae)

The epizoic bonnet limpet Hipponix conicus adheres to various species of sublittoral and littoral gastropods throughout the Indo-West Pacific province. In the northern Sea of Japan, we studied the cause-and-effect relationships of different host species for H. conicus. We investigated five species of host: two muricids (Thais clavigera and T. bronni) and three turbinids (Chlorostoma turbinatum, Omphalius rusticus and O. pfeifferi carpenteri). Our field observations suggest that differences in prevalence among five host species are unrelated to differences in their food habit, shell shape or phylogenetic affinity. The pattern of the prevalence of H. conicus on the two species of muricid hosts differs from that of the primarily littoral barnacle Chthamalus challengeri on the same host species, probably reflecting the amount of time the host species spend emersed in the littoral zone. Our laboratory experiments show that the juveniles of H. conicus died if they spend several hours out of water, and that new hatchlings indiscriminately chose five host species on which to reside when they were continuously submerged. Thus, the differences in the prevalence and intensity of infection of H. conicus in the northern Sea of Japan appear to be more strongly driven by the differential rates of migration and/or survival of the limpets caused by differential duration and frequency of their exposure to the air, rather than preferential adhesion to different hosts.