1) Arthropod family 2) Family portunidae 3) Swimming crabs 
Portunidae is a family of crabs which contains the swimming crabs. Portunid crabs are characterised by the flattening of the fifth pair of legs into broad paddles, which are used for swimming. This ability, together with their strong, sharp claws, allows many species to be fast and aggressive predators. ==Examples== Its members include many well-k...
[n] - swimming crabs
family Portunidae noun swimming crabs