Cognition in the hermit crab, Pagurus samuelis.

My research investigates cognition in the hermit crab, Pagurus samuelis. Cognition can be described as the process of taking in information from the environment and utilizing that information to make decisions. There is a wide variety of information available in the intertidal environment, and hermit crabs must sort through the various stimuli to make a decision.

Hermit crabs have a unique dilemma, their preferred home, food, and mate may all have the same external appearance, that of a specific gastropod shell. Perhaps hermit crabs use different search criteria based on their present need. For instance, if a hermit crab is searching for a new shell it may limit its search to shell shaped objects. On the other hand, if it is searching for food it may focus on the smell of gastropod odors and ignore shell-shaped objects without the odor.

My experiments have explored the various combinations of visual, chemical, and tactile cues that Pagurus samuelis uses in specific situations; shell acquisition, finding food, and avoiding predators. I propose that in each situation hermit crabs utilize a specific information hierarchy with a primary, secondary, and possibly tertiary cue.

Pagurus samuelis is an intertidal hermit crab that lives on the rocky shoreline of Southern California. They are predominantly found in Tegula shells in this area.

Hermit crabs are exposed to multiple stimuli in the rocky intertidal zone, some or which are ephemeral. If hermit crabs can narrow their search criteria and ignore other stimuli, they will exhibit faster and more accurate decision making then if they utilize the same stimuli in every situation.

My research has led to the development of a new behavior model entitled "Cotnextual Decision Hierarchies."