Within-shelter behaviour of the spotted spiny lobster, Panulirus guttatus (latreille), in simulated communal dens: an exploratory study.

Panulirus guttatus is a sedentary spiny lobster that dwells in the coral reef habitat. We conducted an exploratory study to describe the within-shelter behaviour of groups of 4-6 individuals of P. guttatus in simulated communal dens deployed in tanks. Lobsters displayed a diel within-shelter activity rhythm, with a peak shortly before dawn due to an increase in agonistic interactions among sheltered individuals. In a single-chamber cave, aggressions resulted in the constant rearrangement of individuals in the den, related to their preference to cling to the walls. In a triple-chamber cave, the largest male often defended one chamber, but the remaining individuals tended to aggregate in one of the other two chambers during the day. These trends suggest that P. guttatus is a gregarious lobster, but that this gregariousness is influenced by the amount of available shelters and by temporary, size-related social hierarchies. This hypothesis should be tested with fully replicated experiments to help understand the patterns of shelter utilization of P. guttatus in the coral reef habitat. [ABSTRACT FROM AUTHOR]