Abstract
Heterochely is an important feature in some marine decapod crustaceans, but it is seldom investigated in freshwater crayfish. In this study, we applied a biometrical analysis targeting wild populations of three European crayfish species, Astacus leptodactylus, Astacus astacus, and Austropotamobius torrentium, as well as one invasive North American species, Faxonius limosus. Field data were combined with video-recorded observations to understand the usage of chelae in laboratory experiments for A. leptodactylus and F. limosus. According to biometrical measurements, heterochely was evenly distributed between species and sexes in wild populations, leading to the assumption that there is no specific pattern in chela size. Moreover, we found that the ambidextrous usage of chelae is a commonly encountered behaviour in crayfish, since no significant relationship was found between their chelae and asymmetry. This behaviour could maximize the chances of survival for crayfish in general, since losing one or both chelae is often recorded in the wild.
