Student Research Projects

Reaction Time of Clibanarius tricolor in Response to Multiple Stimuli

Student Mikayla Dunnavant, '18
Jennifer Hatstat, '18
Faculty Mentor(s)
Department Biology
Course Biology 385: Animal Behavior

Abstract

Hermit Crabs do an amazing job at cleaning fish tanks. Why? Because their source of food comes from eating waste dropped by fish and the algae that builds up on the rocks and sides of the tank. The hermit crabs that were used for this experiment were all store bought and had never before been predated on. Why then were they so easily startled back into their shells by the movement of objects? During our observational period, we found that Clibanarius tricolor (the Blue-legged Hermit Crab) preformed one behavior consistently: it always came back out of its shell after it was disturbed. We were interested to see if the response time after being disturbed differed if we changed the size of the object we moved in front of the hermit crab or if this response was merely a fixed action pattern. We studied a group of twelve C. tricolor in a lab on the Virginia Wesleyan Campus. All of the hermit crabs we used had been in the same tank since the start of the experiment and were acclimated to each other and to the tank environment. We also made sure to wait a few days between trials in order to ensure we were not putting too much stress on the hermit crabs. We lowered three rocks of different sizes one at a time in front of the hermit crabs and timed how long it would take for the hermit crab to come back out of its shell after being stimulated. We also recorded behavior for a few minutes after each trial to see if the hermit crabs would approach or walk away from the rocks after they came back out of their shells. The responses of the hermit crabs to introduced rocks were wide ranging and we did not see a consistent pattern in the time it took for the hermit crabs to appear from their shells. However, we did find that most hermit crabs would move in the opposite direction of the rock that was lowered in front of them.