Predator-associated cues promote host riding, and coupling to mobile hosts improves survival in an epizoic limpet
Epizoic limpets may reduce predation risk by riding mobile gastropod hosts, but the behavioral steps leading to host attachment and the benefits of attachment remain poorly understood. We examined these issues in the epizoic limpet $\textit{Lottia tenuisculpta}$ using a host-riding assay, paired-trajectory analyses of pre-riding movement, a survival assay, and mucus-conditioning assays. In the host-riding experiment, involving 156 limpets in 39 chambers, crab-associated cues increased attachment within the observation window from 19 of 80 individuals in the cue-absent treatment to 42 of 76 individuals in the cue-present treatment. In the same assay, the high-frequency tail of the locomotor amplitude spectrum became shallower under cue-present conditions, with the posterior median slope shifting from -0.353 to -0.287. Direct analysis of visible paired host-limpet trajectories further showed stronger distance closure under crab-associated cues. Distance closure was quantified over the final visible five minutes before riding or before the final visible paired frame. In the survival assay, based on 31 valid trials, the fitted model indicated lower survival after attachment on fixed hosts than on mobile hosts: the posterior median hazard ratio for fixed versus mobile hosts was 2.111, and posterior median survival at the end of the observation window was 0.437 on mobile hosts but 0.175 on fixed hosts. In a separate single-limpet locomotion assay, gastropod mucus-conditioned surfaces yielded narrower final cumulative-distance ranges than the no-mucus control. Together, these results indicate that predator-associated cues promote host riding, visible paired trajectories reveal a pre-riding approach component, coupling to mobile hosts improves survival, and host-associated surface cues may narrow solitary-limpet movement.