Discipline: Biological Sciences
Cheryl Petsche - University of the Virgin Islands
Many behaviors in nature are based on avoiding predation. One way for an animal to avoid predation is to use camouflage. Dromia erythropus is a decorator crab that is known for mainly using a large piece of sponge for its decoration. To determine the mechanisms of sponge selection by the crab, decoration choice was analyzed in relation to field use, active choice, and differences in handling time of different sponges. Crabs collected in Brewers Bay, St. Thomas (USVI), were most frequently decorated with the sponges Amphimedon compressa and an unidentified purple demosponge, but were found to use at least eight species of sponge. A multiple choice experiment using the sponges Amphimedon compressa, Aplysina fulva, Tedania klausi, Ircinia strobilina and an unidentified demosponge determined that crabs preferred the sponge T. klausi. Video analysis of individually-filmed crabs supported crab preference for T. klausi with a mean total handling time of 2.63 hours (n=3), in contrast to handling times of 4.34-11.06 hours for four other sponges. Curiously, handling time on the unidentified demosponge was higher than that on other low preference sponges, despite its high frequency of use in the field. Data suggest that multiple cues, including biomechanical and chemical, likely determine decoration choice in this crab species. More analyses, including quantification of specific behavioral sequences from videos and experiments on the roles of sponge chemistry, will follow to fully understand decoration preferences.
Funder Acknowledgement(s): VI-EPSCoR, Grant #0814417
Faculty Advisor: Edwin Cruz-Rivera, firstname.lastname@example.org