The ecological consequences of limb damage and loss in decapod crustaceans: a review and prospectus

Autotomy, the reflex severance of an appendage, is considered an adaptation to avoid predators and limit wounds. While an autotomy response may provide immediate survival benefits, the loss of one or more appendages can result in long-term functional and energetic costs. In this paper, we present an overview of the incidence of limb damage and loss in decapod crustaceans; review the literature on the ecological consequences of such injury; and suggest areas for future research. A survey of limb damage and loss in field populations showed consistently high incidences of injury in 14 reviewed species. Typically, chelipeds were the limb type lost most often and injuries were distributed symmetrically. No consistent correlation existed between injury frequency and body size among species. In general, the frequency of injury was independent of sex and moult stage. Fishery practices were responsible for substantial limb loss in some commercial species. In terms of energetic costs, experiments demonstrated that limb injury could reduce growth increment and affect intermoult duration. Functionally, limb damage was capable of reducing foraging efficiency and mating success, and increasing vulnerability to intra- and interspecific attack. The magnitude of these effects depended on the type and number of limbs lost. Given the prevalence of injury in decapod crustacean populations, the costs involved, and the ecological importance of many crustacean species, nonlethal injury has the potential to affect population dynamics and community processes. Convincing evidence of autotomy's effects beyond the level of the individual, however, is, at present, lacking. Future work should redress this shortcoming. In addition, comparative studies are needed on decapod species from different habitats and with different lifestyles before generalizations can be made about the costs and benefits of autotomy.