When to move and where to go: Movement behavior of the tropical littorinidCenchritis muricatus (Linnaeus, 1758)

Movement behavior in intertidal molluscs is related to the intensity of phy sical and biological stress. Tropical littorinids are exposed to extreme en vironmental conditions, and movement at night or on a tidal cycle may allev iate desiccation and heat stress, as would returning to a sheltered locatio n following foraging. We examined the movement behavior of individually mar ked Cenchritis muricatus on a Jamaican shore for 30 days. On 6 days, select ed from different parts of the lunar cycle, snail locations were monitored at 3-h intervals. Movement did not occur on a diurnal, tidal, or lunar cycl e. Although C. muricatus preferentially rested in crevices., there was no e vidence of homing behavior. Snails resting on exposed rock surfaces were fo ur times more likely to move than snails resting in more sheltered microhab itats. In general, movement in C. muricatus appears to occur in direct resp onse to wetting: > 89% of movements occurred within 12 h after rainfall or heavy dew. We believe this behavior is primarily a response to desiccation stress, but it may also facilitate foraging.