The force needed for leg autotomy in the crab Hemigrapsus nudus

ABSTRACT Autotomy is the ability to shed an appendage, and arthropods can autotomize to escape predation or a fouled molting event. Myriad aspects of autotomy have been previously explored, yet quantitative data on the force needed to induce autotomy is lacking. We tested three leg types in Hemigrapsus nudus, and our results showed that hind legs require the most amount of force to autotomize (~45 N-s) compared to claws (~28 N-s) or middle walking legs (~22 N-s). These results rejected our null hypothesis that all legs require an equal amount of force to autotomize as well as our alternate hypothesis that larger legs would require more force than smaller legs. Previous research has suggested that the propensity to autotomize could correlate with the type of appendage, and while we are unable to provide an evolutionary explanation for our results, it is exciting to have some quantitative force data for future studies.