The blue crab Callinectes similis
is a decapod crustacean in the Portunidae
family. It is a strong and agile swimmer powered by a pair of flat, oar shaped rear legs called swimmerets giving it freedom of motion to rapidly swim backwards, sideways, and sometimes forward (Barnes 1980). It is an offshore congener in the genus of Callinectes
. The lesser blue crab has a smoother, more uniform granulated carapace when compared to C. ornatus
and C. sapidus
(Williams 1984). Adult males have a green carapace with irregular areas of iridescence at the base of the teeth. The swimming legs are mottled with white. The females are similar in color except that the inner surfaces of the chelae are more violet blue. The juveniles are not as brilliantly colored appearing olive-yellow to greenish. The length and curvature of the reproductive organs (gonopods) are distinctive in mature males for each of the Callinectes
species (Gore 1977, Barnes 1980) See illustrations from Williams (1974) below.