The influence of chemical cues and conspecific density on the temperature selection of a freshwater snail ( Melanoides tuberculata)

1. The effects of predation risk (via chemical cues) and conspecific density on temperature selection of the freshwater snail Melanoides tuberculata were assessed within a circular thermal gradient. 2. Chemical cues from crushed conspecifics elicited the strongest avoidance response of snails in isothermal conditions. 3. Following the addition of chemical cues to the thermal gradient, snails became more active and did not exhibit significant preference for any area within the gradient. Thus, average selected temperatures were higher when exposed to chemical cues. 4. Although average selected temperatures increased with density of snails within the gradient, differences among densities were non-significant. 5. This species seems to modify its thermoregulatory behavior when exposed to chemical cues (i.e. predation risk) suggesting that snails favor predator avoidance over thermal selection when presented with both demands.