Regeneration in the fiddler crab, Uca pugilator, after injury or removal of limb buds

Abstract

AbstractAfter autotomy of seven appendages and partial regeneration, crabs (Uca pugilator) were subjected to removal of one, three, or six developing limb buds at different stages of limb growth. Removal of one limb had no effect on the growth of the remaining limb buds or the time of ecdysis, and the limb bud removed was not replaced before ecdysis. Removal of six limb buds early in the regenerative period caused a retardation of growth in the remaining bud until the reamputated buds could be replaced. Ecdysis was postponed in these animals. Removal of six limb buds at a later stage, or removal of three limb buds at any stage, produced a slight delay in growth of the remaining bud(s) which was not always statistically significant. The inhibition of growth in the remaining bud(s) was greatest in those individuals which went on to replace the reamputated buds. Such individuals also exhibited a longer time to ecdysis.No inhibition of growth or delay in ecdysis was produced in small crabs (11–12 mm carapace width) by removal of one, three, or six limb buds. These were generally not replaced.Animals which had six limb buds removed early in regeneration showed a greater inhibition of growht in the remaining limb bud than those which had eyestalks as well as six limb buds removed. This latter group, however, did show a significant retardation. This is considered evidence for the production of limbgrowth inhibiting substances in other sites in addition to the eyestalks.Limb buds which had been injured grew more slowly than contralateral control limbs initially, but the difference diminished as the crabs approached ecdysis. Ecdysis was not delayed by the presence of this one incomplete limb bud. This is consistent with the lack of effect of removal of a single limb bud, seen in the previous experiments.