Autotomy in the Asian shore crab (Hemigrapsus sanguineus) in a non-native area of its range

Numerous taxa have the ability to autotomize pans of their bodies to increase survivorship in dangerous or stressful situations. Effects of autotomy on a surviving individual's subsequent ecological function is not well understood for most species. In this study, we provide the first quantification of autotomy patterns within a population (frequency of injured individuals) and within an individual (frequency of missing pereopods, or limbs) of the Asian shore crab Hemigrapsus sanguineus. This crab, member of the family Grapsidae, is a recent introduction to the eastern coast of North America. Of 95 crabs sampled, 42% were missing at least one limb, with larger crabs missing more limbs than smaller crabs. Of the sample, 16% were missing at least one cheliped, with chelipeds more likely to be lost than walking limbs. These rates of limb loss are comparable to those of other crabs in their native ranges. Limb loss patterns affected feeding rate and size of prey consumed. Crabs missing one cheliped fed slower than those with both chelipeds, but consumed a similar ratio of small to large prey as crabs with both chelipeds. Crabs with no chelipeds, which fed at the slowest rate, consumed a larger ratio of small to large prey than crabs with either one or two chelipeds. These feeding results suggest that frequency of limb loss in H. sanguineus autotomy levels has potential to affect several population- and community-level processes.