Portunoidea
Portunoidea is a crab superfamily that includes the swimming crabs in the family Portunidae. The placement of other crab families in Portunoidea is debated and may change with new genetic research.
These crabs usually have a flat, smooth carapace that is wider than long, with shapes ranging from hexagonal to oval. The carapace often has up to nine pairs of spines along the forward edge, though some species lack spines. In some species the end of the first maxilliped is lobed, a feature known as the portunid lobe.
Their claws are typically sturdy, and in some species the last pair of walking legs has oval claws. The sutures between sternum segments 4 to 8 are usually incomplete. In Portunidae, the eighth sternite is often visible from below and has a groove for the male opening.
In males, the abdominal segments may all be free or the third to fifth may be fused, though the sutures are often still visible. The first gonopod is strongly curved with a swollen, hooked base.
Portunoidea is closely related to Xanthoidea. Some families (Hexapodidae and Mathildellidae) are sometimes placed in Xanthoidea, while deep-sea crabs in Geryonidae are usually placed in Portunoidea but sometimes in Xanthoidea. All Portunoidea live in the ocean; a freshwater group called Trichodactylidae is sometimes included in Portunoidea.
There are thirteen families in Portunoidea, four of which are extinct, and it also contains the genus Garthopilumnus.
This page was last edited on 2 February 2026, at 18:35 (CET).