88.1 Friday, Jan. 6 Opposites attract: Lobsters prefer to share dens with opposite behavioral phenotypes CHILDRESS, M.J.*; HELDT, K.A.; MCCLELLAN, K.L.; Clemson University; Clemson University; Clemson University email@example.com
Caribbean spiny lobsters are known to be gregarious and are often found sharing dens with conspecifics. Previous work has found that gregarious lobsters may benefit from a reduction in predation though decreased time to find dens (guide effect), decreased risk of predation (dilution effect) or increased probability of survival once attacked (group defense). Despite these benefits of being gregarious, half of all juvenile lobsters in the Florida Bay nursery are found in dens by themselves. In this study, we compared the odor preferences and den choices of juvenile lobsters in relation to familiarity and dominance status. Wild-caught juvenile lobsters were housed with size-matched conspecifics and in aquaria with a single shelter. We recorded the number of aggressive acts and assigned dominant status to the individual with the highest average. Then both dominant and subordinate individuals were allowed to choose between the odors of familiar/unfamiliar and dominant/subordinate conspecifics in a Y-maze choice test. Both dominant and subordinate lobsters showed no general preference for odors of conspecifics, but significantly preferred odors of opposite social status. To test if this preference would influence den choice, ten pairs of familiar lobsters were released into a large mesocosm with ten identical artificial crevice shelters. The frequency of co-denning between opposite social status lobsters was higher than predicted by random chance. These results suggest that juvenile spiny lobsters are more attracted to conspecifics of opposite social status and are more likely to share shelters with these individuals. We hypothesize that such a choice reduces aggression between den-mates and thus reduces the costs associated with sharing crevice shelters.