Factors affecting individual variation in resting site fidelity in the patellid limpet, Cellana toreuma (Reeve)

An investigation was made of individual variation in resting site fidelity in the limpet, Cellana toreuma, with special attention to the adaptiveness of its homing behaviour. Limpets resting in the higher part of the study site showed strong resting site fidelity while those in the middle part showed weaker fidelity and tended to shift their resting sites to higher parts. Limpets resting in the lower part where there were an abundant supply of food and high predation intensity, had the strongest resting site fidelity and always returned to fixed resting sites with mucous sheets. The resting site fidelity varied continuously among individuals. Four causes for shift of resting site were detected: fleeing from starfish, Coscinasterias acutispina, pushing contests for resting site, non‐returning excursions following and without following other's trail. The frequency of shift of resting sites due to each of these causes varied among individuals. Estimation of energy budget during about half a month showed that the location of resting site and frequency of shift of the site considerably affected the growth of limpets through energy expenditure by respiration and stationary mucus secretion, and energy intake by foraging. These variations were proposed as being a result not of density dependent dispersal nor adaptation to a single factor such as desiccation, heavy wave impacts or predation, but being due to individual difference in a compromise between two conflicting factors, susceptibility to predation and accessibility to food resources.