View of the underside of a female (left) and a male (right). Note the broader, more rounded abdomen on the female and the narrower, pointed abdomen on the male.
View of the underside of a male Hemigrapsus oregonensis. Male brachyuran crabs have no pleopods on their abdomen except for two hemipenes used for transferring sperm.
This individual from Kalaloch also shows the hairy legs (actually setae not hairs) common on this species, plus the three teeth on the anterolateral margin of the carapace which distinguish genus Hemigrapsus from Pachygrapsus crassipes (which has only two teeth). Although abundant setae on the legs is characteristic of H. oregonensis and are evident in this individual, most individuals found near the Rosario Marine Labs have very few setae on the legs. Photo by Dave Cowles, July 2009
