Claw allometry in green crabs, Carcinus maenas: heterochely, handedness, and sex
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Claw loss and reversal of handedness during regeneration are common phenomena in heterochelous decapod crustaceans, which typically have one large ‘crusher’ claw on the right side and a smaller ‘cutter’ claw on the left. Little is known about the relative importance of claw growth vs. body growth during claw regeneration. Here the relationship between claw size and body size of green crabs, Carcinus maenas, was examined to test for differences in claw allometry as a function of handedness and sex, as there are differences in how males and females use their claws. A total of 730 crabs (range = 15.7–83.6 mm CW) were collected from Maine to New Jersey, USA from May to October 1997, 2000, and 2004–2005. Claw growth, particularly crushers, was accelerated in left-handed crabs and in males compared to right-handed crabs and females respectively. These differing growth strategies highlight the role of sexual dimorphism in claw usage and the importance of achieving heterochely after claw injury. These results imply that handedness should be an important factor to consider in future studies of crab morphology, behavior, and morphometrics.
KeywordsCarapace Width Body Growth Green Crab Male Crab Stone Crab
This project was funded in part by the Richard Cronin Fisheries Research Fund and the Woods Hole Scholarship Fund from the University of Massachusetts, by a Cooperative State Research, Extension, and Education Service, U.S. Department of Agriculture, MA Agricultural Experiment Station Hatch grant, and by a University of Pittsburgh at Johnstown Research Council Small Grant. We thank Connecticut College for use of space and equipment, Normandeau Associates for help with crab collections, and Rutgers University Marine Field Station, Suffolk University Friedman Field Station, and Wells National Estuarine Research Reserve for access to lab space and field sites. Writing was completed while the senior author was a Center Fellow at the National Center for Ecological Analysis and Synthesis, a Center funded by NSF (Grant #DEB-0553768), the University of California, Santa Barbara, and the State of California. We thank LD Smith for a thorough review of the manuscript and his insightful comments, as well as three anonymous reviewers, all of whom helped in producing a better manuscript.
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