GREEN CRABS, CARCINUS MAENAS, AND AN EXAMINATION OF THE EFFECT OF CLAW AUTOTOMY ON DIET

Like other decapod crustaceans, the green crab Carcinus maenas can actively amputate limbs by the process of autotomy. The loss of limbs may have consequences for the future fitness of an individual, since it is likely to impose energetic costs, including a reduced foraging efficiency. This study examined the occurrence of limb loss and the effects of claw autotomy on the diet of green crabs. Green crabs were collected from May-October 1995 from sites in New England. All crabs (N = 1,504) were examined in the field, and 402 adult crabs (>30 mm wide) were included in the analysis of gut contents. Overall, females experienced more injuries (38.4% missing at least 1 limb, N = 277; 17.89% missing 1 or both claws, N = 129) than males (32.18% missing at least 1 limb, N = 252; 14.8% missing 1 or both claws, N = 116). The overall incidence of autotomy generally increased with increasing crab size, but the incidence of claw autotomy did not. The most common identifiable materials in the guts were the hard parts of molluscs, arthropods, and annelids. The contents of the guts differed between sites, but was not significantly different for crabs missing claws than for intact crabs. Thus, the loss of a single claw does not seem to alter crab diet.