Growth and Regeneration Patterns in the Fiddler Crab,uca Pugilator

The fiddler crab, Uca pugilator, will survive several intermolt cycles in the laboratory, but the cycles are irregular. Variations in cycles are due to variations in the length of stage C4. The transition from C4 to D in intact crabs does not seem to be due to environmental clues because crabs kept in constant conditions for long periods of time continue to have extremely variable intermolt cycles. Multiple autotomy triggers the onset of proecdysis and a post-autotomy intermolt cycle that is significantly shorter than controls. Multiple autotomy-induced proecdysis is divided into two phases: the "reset event" is independent of the eyestalks, while the "proecdysial program" is normally under their control. Loss of a cheliped is more effective in initiating a reset event than is loss of a single walking leg. Eyestalk removal forces crabs into proecdysis. If crabs are in early proecdysis (stage D0) at eyestalk removal, the proecdysial period is accelerated. Eyestalk removal results in large increases in size at ecdysis which can be blocked by multiple autotomy. Ecdysis does not always result in growth. Molting in Uca may result only in regeneration of missing limbs. Crabs regenerating a number of limbs may actually become smaller at molt.