The effects of cheliped autotomy and regeneration on aggression in purple shore crabs (Hemigrapsus nudus)

Abstract

Studies on appendage regeneration often speculate whether the regrowth of a leg or tail is an adaptive process. However, almost all of these studies have had experimental comparisons between two specific treatment groups: (1) control animals that have never autotomized and (2) animals that autotomized and subsequently regenerated. To truly understand the evolutionary significance and adaptive value of appendage regeneration, comparisons must include animals that have autotomized but not regenerated. The aim of this study was to apply this novel perspective on regeneration and aggression in the purple shore crab, Hemigrapsus nudus. Both retreat and aggressive behaviors were compared among normal males, males with autotomized claws, and males with regenerated claws. Our results demonstrated a reduction in aggressive behaviors and an increase in retreat behaviors in both autotomized and regenerated males. However, since chelipeds are not used exclusively for intrasexual selection in many decapods, future experiments will be needed to demonstrate the overall adaptive value of cheliped regeneration.

Keywords:

• crab
• Hemigrapsus nudus
• cheliped
• claw
• autotomy
• regeneration
• fight
• aggression

Acknowledgement

NOAA Scientific Taking Permits 16434 and 17239 were used to collect animals for this study.

Disclosure statement

The authors have no competing or financial interests.

Additional information

Funding

This work was supported by the M.J. Murdock Charitable Trust [grant number 2012225].