Effects of Predator Chemical Cues On Snail Avoidance Behavior

Predator and prey relationships are complicated by the fact that predators affect prey behavior and their ability to obtain necessary resources for their survival. Snails detect chemical cues from predators and respond by altering their behavior. The presence of predators causes snails to reduce their foraging behavior and instead engage in avoidance behaviors. Crayfish and pumpkinseed sunfish are two common predators on freshwater snails. Because crayfish forage along the benthos, while pumpkinseed sunfish forage higher in the water column, they present different predation risks. Two common snail avoidance behaviors are climbing and burrowing and we hypothesize the snails can differentiate between predators and respond by engaging in different avoidance behaviors.  Our study examines the avoidance behavior of two freshwater snails (Helisoma trivolvis and Bellayma chinensis) in the presence of crayfish and pumpkinseed sunfish. Eight snails were placed into trials and their behavior (climbing, burrowing, or foraging) was recorded after 1 hour. During trials predators were held in containers with mesh sides to allow diffusion of chemical cues in the water. The different predator treatments were 1 crayfish, 1 pumpkinseed sunfish or both 1 crayfish and 1 pumpkinseed sunfish present. Our expected results are that Helisoma trivolvis and Bellayma chinensis will engage in climbing behavior in the presence of crayfish and they will engage in burrowing behavior in the presence of pumpkinseed sunfish. In the presence of both predators, we expect equal numbers of snails to engage in both climbing and burrowing behavior.