Gregariousness and sociality in spiny lobsters: implications for den habitation

Influences of shelter construction and conspecific attraction on den habitation by the spiny lobster, Panulirus interruptus Randall, were explored using field observations and laboratory experiments. Lobsters were often found aggregated in crevices of rocky reefs, with juveniles cohabiting more frequently than larger adults. No association was found between cohabitation and lobster gender. In laboratory tests, individual lobsters preferred large over small sized shelter, though preference was neither fully a consequence of outer shelter dimensions nor inner habitable space. Individual lobsters preferred only shelters suitable for future cohabitation and paired lobsters cohabited more often than expected by chance. Conspecific odor was attractive and caused aggregation; thus, results indicate an intrinsic gregariousness that structures den residency and lobster spatial distribution.