WU, XIAOHUI; DURICA, DAVID/S; HOPKINS, PENNY/M; Univ. Of Oklahoma, Norman; Univ. Of Oklahoma, Norman; Univ. Of Oklahoma, Norman: An atypical regeneration in the fiddler crab Uca pugilator -observation of autotomy-independent limb regeneration

When injured, the fiddler crab Uca pugilator can reflexively cast off a damaged limb at a predetermined site proximal to the injury. This reflex severs the damaged limb adjacent to the body wall, between the basioschiopodite and coax. Autotomy, therefore, normally leads to the loss of all limb segments. Normal regeneration of autotomized limbs accompanies the animal�s molt cycle, and newly formed limbs emerge as the animal undergoes ecdysis. Under laboratory conditions, however, another kind of limb regeneration was observed that was not associated with autotomy. Newly molted crabs were found to regenerate amputated limbs without the loss of all segments distal to the coxa. Regeneration occurred normally at every amputation site tested, including cuts at the propus, carpus and merus. Only the missing structures were regenerated, with appropriate proximal-distal segmentation. Newly regenerated limbs grow from the amputation site and complete limbs emerge at ecdysis similar to normal autotomy-associated limb regeneration.