Document Type

Honors Thesis


Marine Science


Sara Lindsay

Committee Members

Paul Rawson, Jordan LaBouff

Graduation Year

May 2023

Publication Date

Spring 2023


Littorina littorea is an intertidal, invasive gastropod species common in the Gulf of Maine. In this paper, I studied the avoidance and risk-reducing behavioral responses of L. littorea to predation risk by invasive crustacean species Carcinus maenas. Avoidance and risk-reducing behavior in this study are defined by the tendency to move towards the edge and out of a simulated tide pool and the tendency to reduce feeding. The goal of this study was to determine whether the exposure to chemical cues of predators resulted in an increase in avoidance behavior, risk-reducing behavior, and a reduction in the time before the first movement was observed. The cues I studied included exposing snails to water containing the scent of C. maenas, treating them with water containing the scent of crushed L. littorea, or treating them with water containing the combined scent of C. maenas foraging and crushed L. littorea. Littorina littorea was found to increase both risk-reducing and avoidance behaviors in the presence of predatory crabs alone. There was no significant change in behavior in snails exposed to crushed L. littorea alone.

However, when exposed to the combined treatment, there was only an increase in risk- reducing behaviors, not avoidance behaviors. In addition, the snails treated with the combined treatment exhibited avoidance behaviors earlier than snails in the other two treatments. My observations of behavioral interactions between Littorina and Carcinus contribute to the knowledge of key trophic interactions between two non-native species of the intertidal community in Maine. Such studies are of increasing importance as invasive species continue to impact Gulf of Maine ecosystems.