MILLER, L. P.; Hopkins Marine Station, Stanford University: Functional significance of littorine snail “standing off” behavior for control of body temperature during aerial exposure

Littorine snails living in the high intertidal zone must often endure high body temperatures during daytime low tides, which can put them near their physiological thermal tolerance limits. In order to help control body temperature while minimizing water loss due to desiccation, many littorine snail species exhibit a behavior in which they glue the lip of the shell to the substrate, stand the rest of the shell up off the substrate, and withdraw the foot into the shell, presumably minimizing contact with the rock and maximizing shell surface area available for convective heat loss. Using silver models of several littorine species in a wind tunnel, I have explored the importance of this �standing off� behavior for minimizing conduction from the rock and enhancing convective heat loss. Initial results indicate that the lowered rate of conduction from the hot rock substrate may be more important than the increase in shell area exposed for convective heat loss. Ultimately the ability to control shell and body temperature appears to be more important to these snails than the increased risk of dislodgement by incoming waves due to the �standing off� behavior.