Females have broad triangular or rounded aprons and red fingers on the chelae, whereas in the male the abdominal flap, or apron, is shaped like an inverted 'T'. To accommodate swimming, the fifth leg is adapted to a paddle-like shape, as is the same with other portunids.
The remainder of the body is shaded an olive brown color. Callinectes sapidus is easily identified by its body color which is generally a bright blue along the frontal area, especially along the chelipeds (the appendages bearing a 'chela' or pincher-like claw).
