Autotomy patterns in the Japanese mitten crab, Eriocheir japonica

Abstract

Autotomy is a common phenomenon in crustaceans and has been extensively studied. The Japanese mitten crab, Eriocheir japonica, is an important fisheries species in Japan, but autotomy patterns of this species have seldom been reported. Therefore, in this study, we examined the autotomy patterns for E. japonica in both growth and reproduction habitats. Our results indicated that a high proportion (more than 26%) of E. japonica lost appendages, and autotomy rate was positively correlated with crab size. There was no significant difference in autotomy frequency between sexes, and single appendage loss was the most common form of autotomy. Appendages on the left and right sides had an equal probability of loss. The observed autotomy frequency was significantly different from the expected frequency, which suggests that in E. japonica the autotomy event is dependent on each other. Moreover, appendage loss in E. japonica was affected by habitat type and season.