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.
Many crabs "slobber" bubbles when out of water because they are pumping air and water in their gill chambers, whose outlets are near the mouth. Photo by Dave Cowles, Sept 2005
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.
