On the Sex Ratio of the Painted Ghost Crab Ocypode Gaudichaudii H. Milne Edwards & Lucas, 1843 (Brachyura, Ocypodidae)

The sex ratio of the painted ghost crab Ocypode gaudichaudii is 1 : 1. When sampled in different areas of the intertidal zone, the number of males and females varied according to differences in their spatial patterns of behaviour. Male crabs that remained in the burrow area, i.e., the upper third of the beach, at low tide outnumbered females 2 : 1. Large sexually mature males were more abundant in the upper third of the beach in the burrow area than near the low-tide mark. Equal numbers of males and females foraged away from the burrow area at the waters edge. Twice as many females were captured away from the burrow area than in it. Previous reports of skewed sex ratios may have resulted from sampling bias introduced by the different behaviours of each sex.