Date of Award

Spring 5-6-2021

Document Type


Degree Name

Master of Biological Science (MBioSci)


Biological Science

First Advisor

Melanie DeVore

Second Advisor

Kristine White

Third Advisor

David Weese


The Caribbean terrestrial soldier crab, Coenobita clypeatus(Fabricius 1787), coexist and utilize the shells of numerous species of land and marine gastropods. Soldier crabs rely on gastropod shells for protection as the crabs have a soft abdomen, leaving them vulnerable for predation and desiccation, threatening their survival. This creates a strong pressure to obtain well-fitting shells that provide adequate protection against water loss. Cerion of Röding (1798) shells are one of the most commonly used shells among living colonies of C. clypeatuson San Salvador Island. This study is interested in the frequency of shell use by C. clypeatus crabs based on several colonies and associated assemblages of discarded shells on San Salvador.In this study, unoccupied shells from the areas inhabited by C. clypeatus crabs were collected and measured to determine preference for shell type. Additionally, this study examined how discarded shells from three colonies of C. clypeatus crabs are modified and highly adapted for a better fit. Percentages of cerionids collected in the assemblages of discarded shells ranged from 75% to 89.5%. The following shell modifications were included in this study: aperture lip modifications, inner aperture ridge modifications, hollowing out the columella, umbilicular region modifications, and exterior holes. This study provides insights regarding shell locations, shell sizes, and shell modifications that can determine C. clypeatus population demographic and location. Additionally, this present study also provides a means for those using electron spin resonance dating of terrestrial quaternary shells to recognize if shells were used by soldier crabs and were transported into a depositional environment.