GROWTH AND REGENERATION PATTERNS IN THE FIDDLER CRAB,UCA PUGILATOR

Abstract

Regeneration of lost walking legs in the fiddler crab Uca pugilator is divided into three distinct phases-wound healing, basal growth, and proecdysial growth. By means of HPLCI RIA analysis of levels and composition of endogenous ecdysteroid hormones and in vitro assays of 14C-leucine incorporation, we have determined that the transition between anecdysis and proecdysis is the point at which limb bud growth is most affected by ecdysteroids. The growth that occurs during proecdysis is programmed during the anecdysislproecdysis transition by a small peak of ecdysteroids (Peak I). Early exposure to 20-hydroxyecdysone at this critical window is necessary for further proecdysial growth of limb buds. The later peak of ecdysteroids (Peak 11) seen in the hemolymph of these crabs during late proecdysis does not seem to be involved in the regeneration process.

Regeneration of major cheliped after the mating season in the hermit crab <i>Pagurus middendorffii</i>

“…R-males, moreover, molted more often than C-males, suggesting that major cheliped autotomy still facilitates the next molt. This is consistent with the prior study of P. middendorffii (Yasuda et al, 2014) as well as other studies on crustacean (Hopkins, 1982;Juanes & Smith, 1995), and our results also suggest this facilitation of molting occurs even in seasons when the molting frequency is very low.…”

Rapid regeneration of the major cheliped in relation to its function in male-male contests in the hermit crab Pagurus middendorffii

“…These results differ from other studies dealing with cheliped regeneration of brachyuran crabs. Although many studies have demonstrated that major cheliped regeneration decreases body size increment at first molt (Bennett 1973, Hopkins 1982, Smith 1990, Cheng & Chang 1993, McLain & Pratt 2011, this smaller growth increment is not observed for the second molt in the blue crab Callinectes sapidus (Rathbun) (Smith 1990) and the fiddler crab Uca pugilator (Bosc) (McLain & Pratt 2011). Major cheliped regeneration in P. middendorffii males thus continues to be highly costly even at the second molt, suggesting the importance of regeneration in this species.…”

“…Decapod crustaceans have been shown to be able to either shorten or prolong intermolt period before the molt following cheliped autotomy (Hopkins 1982, Juanes & Smith 1995, indicating alteration in physiological conditions in order to regenerate the lost cheliped. Alteration in molt timing would also be expected to occur in male P. middendorffii with major cheliped loss as a result of physiological requirements for regeneration.…”

The ecological consequences of limb damage and loss in decapod crustaceans: a review and prospectus

“…Limb loss is known to reduce moult increment (e.g. percent increase in carapace width at the moult) in various decapod species (Hiatt, 1948;Hughes & Matthiessen, 1962;Bennet, 1973;Kuris & Mager, 1975;Savage & Sullivan, 1978;Davis, 1981;Hopkins, 1982;Ary et at, 1987;Smith, 1990b;Cheng & Chang, 1993;Moriyasu et aI., unpubl. data).…”

“…Reductions in growth increments become evident as more limbs are lost (Bennett, 1973;Chittleborough, 1975;Kuris & Mager, 1975;Hopkins, 1982;Smith, 1990b, but see Davis, 1981. Skinner (1985) termed this phenomenon "regenerative load", where the size increase at the moult will be devalued by the extent of regeneration required.…”