Burrow Usurpation and Duration of Surface Activity in Scopimera globosa (Crustacea : Brachyura : Ocypodidae)

Abstract

Burrow usurpation and duration of surface activity were studied for the ocypodid crab Scopimera globosa in the Fukuro River Estuary, southern Honshu, Japan. Burrow owners were displaced frequently during an exposure period, where burrow usurpation accounted for almost half of the causes of burrow abandoning. In most instances of burrow usurpation, the usurper was larger than its opponent, irrespective of the sex. The duration of surface activity during an exposure period was not correlated with crab size. Based on these facts, the reason for size variations in spatial distribution of S. globosa is discussed.