Alarm pheromones in aquatic snail species: schreckstoff and stuff

Many aquatic organisms show alarm responses to chemical cues. For my thesis research, I tested whether two species of aquatic snail (one freshwater and one estuarine) show response to chemicals released by a crushed conspecific. I measured behavioral reaction of a freshwater snail and an estuarine snail species. I first tested the species from a freshwater pond, comparing the behavior of snail exposed to crushed snail extract with controls over a period of 24 h. In the first trial, significantly more snails climbed out of the water at the 8-h mark (χ2=8.86, p<.05) and the 24-h mark (χ2=4.98, p<.05). In the second trial, this difference was significant at the 2-h mark (χ2=4.43, p<.05). In one trial with estuarine snails, I found no evidence of an alarm response. The differences in response between the two species may relate to differences in environment. Alarm chemicals may supply useful information on local predation in a pond with little water movement, but not in an estuary, where water flow would quickly disperse these chemicals.