Abstract
The mating behavior of the grapsid crab Gaetice depressus was investigated with reference to the relative body size of males and females of the mating pairs. In laboratory tanks, sexually active males and receptive females were held together and their behaviors recorded with a video camera. When males were larger than females in the pairs, mating usually began with female approach to the male, and they continued to make contact with each other after copulation. In contrast, when males were smaller than females, mating usually began with male approach to the female, and they parted shortly after copulation. The straddling of females by males before copulation and the female-over-male copulatory position were observed regardless of the relative body size of the pairs. The difference in the female's behavior between the matings with larger and smaller males suggests that females prefer males larger than themselves.
