[1][2][3] Hippoids are adapted to burrowing into sandy beaches, a habit they share with raninid crabs, and the parallel evolution of the two groups is striking.

[4] In the family Hippidae, the body is almost ovoid, the first pereiopods have no claws, and the telson is long, none of which are seen in related groups.

[7] Alongside hermit crabs and allies (Paguroidea), squat lobsters and allies (Galatheoidea) and the hairy stone crab (Lomis hirta, Lomisoidea), Hippoidea is one of the four groups that make up the infraorder Anomura.

[9] The fossil record of sand crabs is sparse,[10] but extends back to the Cretaceous period.

[4] Sand crabs are placed in three families (exclusively fossil taxa are marked †):[11][12]