Uca pugilator

About: Uca pugilator is a research topic. Over the lifetime, 376 publications have been published within this topic receiving 12303 citations.

Variation in the Boldness of Courting Sand Fiddler Crabs (Uca pugilator)

Abstract: Individuals can express boldness in their readiness to resume courtship signaling following a perceived threat. The degree of boldness that is selectively favored depends on the magnitude of costs and benefits that may vary across time and space. We examined within- and between-individual variation in the boldness of courting male sand fiddler crabs, Uca pugilator, across an entire breeding season at a South Carolina (USA) salt marsh where courtship is restricted to supratidal embankments. Boldness was assessed by the time to re-emergence and the number of re-emergences of males who were purposely startled into their breeding burrows once every 3 min for a total of five times. The two measures of boldness were significantly positively correlated. Courting males are on average bolder when their density is high and when tidal conditions correspond to peaks in the number of females moving over the embankment surface. Time to re-emergence increases with successive startles although some males consistently re-emerge faster than others. Large males are not bolder than small males. When male density is high, nearest neighbors frequently re-emerge at the same time, suggesting that males cue on the responses of other nearby males, perhaps by assessing substrate vibration. This may reduce the chance of losing a potential mate to a local competitor.

Eyestalk regulation of molt and vitellogenesis in uca pugilator

Abstract: 1. The condition of the ovaries of intact and eyestalkless Uca pugilator from Florida was examined throughout the period from mid-September to the end of May. The frequency of molt for the animals was also observed.2. Ovarian weights for intact crabs decreased from September to December and began to increase in January. The increase did not occur uniformly throughout the population, and by March all stages of maturation were present. First oviposition occurred in April, involving about 30% of the females. No oviposition occurred as late as mid-September.3. Crabs that oviposited in April did not exhibit further vitellogenesis prior to molt which occurred in late May. A high frequency of molting again occurred in intact crabs in November and December.4. Removal of eyestalks led to initiation of vitellogenesis in immature ovaries at all times tested and also appeared to increase the rate of vitellogenesis in already maturing ovaries.5. Removal of eyestalks increased the frequency of molt maximally in Septemb...

Intrageneric predation by fiddler crabs in south carolina

Abstract: In South Carolina, two species of fiddler crab, Uca pugilator and U. pugnax, often feed in droves on the sand flats of smooth cordgrass salt marshes. Another fiddler crab, U. minax, does not drove, but large males of this species occasionally move onto sand flats and prey on members of the other smaller species. Successful predatory attacks entail a pounce, entrapment of prey in ambulatory appendages, reorientation of the predator to the supine position, maneuvering of the prey between the dactyl and propodus of the major cheliped, killing the prey by piercing or crushing its carapace with the major cheliped, and consumption. Females are successfully attacked with higher frequency than males. The frequency of predatory attacks declines exponentially as the composition of droves becomes biased towards larger males. This may indicate that predators face injury when attacking large males because only males possess potentially defensive claws and claw length increases with the square of body width. Uca pugilator individuals form pods in response to the approach of a predator. Pods are tight clumps of fleeing individuals that may function as mini-selfish herds. Pod composition is biased towards individuals most susceptible to U. minax predation, females and males of small body size, suggesting that pod formation is a selectively advantageous behavior.

Effects of ecdysterone, inokosterone and eyestalk ablation on limb regeneration in the fiddler crab, Uca pugilator

Abstract: Bilateral ablation of eyestalks or injection of either ecdysterone or inokosterone (two 25-μg doses or five 10-μg doses into crabs weighing on an average 1.5 g) caused precocious proecdysis and ecdysis in the fiddler crab, Uca pugilator. On a weight basis ecdysterone was more effective than inokosterone in exerting the effects. Whether the accelerated proecdysis was accompanied by regenerative limb growth depended on the degree of limb bud development at the time of treatment with ecdysones. Ecdysterone and inokosterone blocked the initiation of basal limb growth when administered as two 25-μg doses into crabs exhibiting scar tissue without any visible limb bud. When injected into crabs with limb buds in various stages of basal limb growth exogenous ecdysones accelerated basal limb growth and led to proecdysial limb growth. The degree of acceleration of limb bud growth noticed within three to six days after injection of ecdysones into crabs with limb buds in early stages of basal limb growth was greater than that resulting from eyestalk ablation. In crabs with limb buds in later stages of basal growth, the degree of acceleration of limb bud growth evoked by exogenous ecdysones was similar to that resulting from eyestalk ablation. The final sizes of the limb buds preceding ecdysis in eyestalkless crabs and crabs injected with ecdysones depended on the proecdysial duration available for regeneration. The rate of proecdysial limb growth has been known to vary with the speed at which the crabs complete the proecdysial stages of the molt cycle. This study shows that the time required for the initiation and completion of the basal limb growth also varies depending on how soon the intact and eyestalkless crabs approach proecdysis and ecdysis.