Seasonal utilization patterns of two snail hosts by the epizoic limpet Lottia tenuisculpta (Gastropoda: Patellogastropoda)

Seasonal changes in prevalence rate and number of the epizoic limpet Lottia tenuisculpta on its gastropod hosts, Omphalius nigerrimus and Reishia clavigera, were investigated in Shirahama, Wakayama Prefecture, Japan. Monthly samplings conducted from September 2013 to September 2014 revealed that L.tenuisculpta disappeared from the host in winter and new recruits appeared in early spring. Limpets remained on their host up to a critical shell length of 7 mm on O. nigerrimus and 5 mm on R. clavigera. Capture-recapture method confirmed limpets reaching these sizes migrate onto rock surfaces. Additionally, the effects of the host sizes on their epizoic limpets were examined using a hierarchical Bayesian model. The model showed that limpet shell length decreased with the increasing number of conspecifics on both host species. The shell width of O. nigerrimus had a slightly negative effect on the shell length of limpets, whereas that of R. clavigera had a positive effect on it. Our study revealed the host utilization of epizoic limpets changed seasonally and differed between host species. We suggest that both physical and biological factors of hosts affect the growth, survival, and attachment of the epizoites. •・Epizoic life-history of the limpet Lottia tenuisculpta was investigated.•・The limpet migrated from host shells onto rock surfaces after grown up.•・Sizes at migration were different depending on the host species.•・Shell length of the limpet was affected by conspecific number and host size.