The carapace (shell) varies in color from bluish to olive green, and can reach up to 9 inches across. The claws are bright blue. Those on mature females feature red tips. They have three pairs of walking legs and a rear pair of paddle shaped swimming legs. Males have a strongly tapered abdomen, or "apron," that resembles an inverted T. Mature females have a broad, rounded abdomen. Immature females have a triangular abdomen.