Abstract
The cheliped handedness of four portunid species was examined. The statistical analysis of three species, Thalamita sima, Charybdis (Gonioneptunus) bimaculata and Charybdis (Charybdis) japonica showed no distinct increase in the percentage of left-handed crabs in relation to size. This indicates that left-handed crabs develop their handedness innately. In Portunus (Monomia) argentatus a significant increase in the percentage of left-handed individuals in relation to size was confirmed. In this species left-handedness has probably arisen following the loss of the righthanded crusher.
