Uca pugilator

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

Response to perceived predation threat in fiddler crabs: trust thy neighbor as thyself?

Abstract: Prey require information if they are to respond to predation threat in a risk-sensitive manner. One way that individuals can obtain this information is through the predator-mediated, threat-induced behavior of conspecifics. We examined such a possibility in a refuge-seeking species, the sand fiddler crab (Uca pugilator). Crabs were either exposed directly to a simulated predation threat (a moving cylinder) or the threat-induced response of a near neighbor. We found that fiddler crabs responded to the flight of their neighbors even when they, themselves, were not privy to the stimulus that induced their neighbor’s response. However, the wider range of behaviors exhibited by these crabs—which included no reaction, freezing, running back to the burrow entrance, and burrow retreat—suggest that ‘non-threatened’ crabs either (1) perceived the gravity of the predation threat differently from their directly threatened neighbors and/or (2) engaged in behaviors that allowed them to acquire further information in the face of uncertainty. Conspecific behaviors also had an effect on the hiding duration of crabs, with individuals hiding longer if they saw both the predation threat and the flight of their neighbor. Our results suggest that cues provided by conspecifics can play an important role in guiding the antipredator response of refuge-seeking prey.

Methylmercury effects on regeneration and ecdysis in fiddler crabs (Uca pugilator, U. pugnax) after short-term and chronic pre-exposure

Abstract: Methylmercury (meHg) inhibits limb regeneration and molting in fiddler crabs. The present study shows that, inUca pugilator from a clean site, the inhibitory effects of 0.5 Μg/ml meHg were unaffected by short term pre-exposure to low levels (0.06 or 0.1 Μg/ml) of meHg under laboratory conditions. Chronic exposure tests onUca pugnax showed that the inhibitory effects of meHg varied with the sex of the crabs and the level of contamination at the site of collection. These effects were less pronounced in crabs from an area subjected to heavy metal pollution (Piles Creek, Linden, NJ) than in crabs from a relatively cleaner area (Big Sheeps-head Creek, Tuckerton, NJ). The order of susceptibility to meHg according to its interaction with sex and site from least susceptible to most was: Piles Creek females, Piles Creek males, Tuckerton males, Tuckerton females. Residue analysis showed that all groups absorbed equivalent amounts of mercury, but only the females from Piles Creek were able to depurate to near control levels after two weeks in clean water.

Comparison of the abilities of α-ecdysone and 20-hydroxyecdysone to induce precocious proecdysis and ecdysis in the fiddler crab, Uca pugilator

Abstract: 1 The effects of single, double or multiple injections of α-ecdysone and 20-hydroxyecdysone on molting and limb regeneration in the fiddler crab, Uca pugilator, were determined 2 A single injection of 12 μg of 20-hydroxyecdysone failed to initiate proecdysis in crabs weighing 12 to 16 g Administration of 12, 5, and 5 μg of 20-hydroxyecdysone on Days 0, 3, and 6 respectively induced precocious initiation of proecdysis but not precocious ecdysis However, when two large dosages (20 or 25 μg) of 20-hydroxyecdysone were injected within a period of one or two days all the crabs completed proecdysis and initiated ecdysis precociously but failed to complete the ecdysis and died 3 Administration of 25 μg of α-ecdysone as a single injection failed to initiate precocious proecdysis However, when two injections of 25 μg each were given 36% of the crabs completed proecdysis and successfully molted precociously Injection of larger dosages (80 μg α-ecdysone either as four 20 μg injections or two 40 μg injections) induced precocious proecdysis and ecdysis in 75–86% of the crabs In contrast to the crabs which died during ecdysis after receiving high dosages of 20-hydroxyecdysone, the recipients of α-ecdysone underwent successful ecdysis and their postecdysial survival was normal 4 The response of the regenerating limb buds depended on the dosage of the ecdysones administered Dosages of 20-hydroxyecdysone which failed to initiate proecdysis promoted basal limb growth Stronger dosages of 20-hydroxyecdysone and α-ecdysone which induced precocious proecdysis and ecdysis accelerated limb growth and caused proecdysial limb growth The slope of the growth curve obtained for the crabs injected with high dosages of ecdysones was much steeper than that for eyestalkless crabs 5 The interrelationship between regenerative limb growth and proecdysis and the possible role of ecdysones in the control of proecdysial events in crustaceans are discussed

Respiratory metabolism of the fiddler crab uca pugilator from two different latitudinal populations

Abstract: Determinations of the respiratory rates of Uca pugilator from two different latitudes (Woods Hole and Florida) have been made at 1.4° and 15° C.1. Woods Hole Uca pugilator show a higher rate of metabolism at low temperature than do specimens of the more southerly populations.2. Uca pugilator from the higher latitude are less sensitive to temperature changes than Uca pugilator of same weight from a southern latitude. This has been shown by a lower Q10 for the Woods Hole population.3. Woods Hole Uca are more resistant to low temperature than Florida Uca.4. The same experiments made after the animals have been left at a common temperature of 20° C., show that a stay of seven or eight weeks under similar conditions does not abolish the metabolic differences observed between populations.5. These physiological characteristics and some morphological ones might be used to distinguish two subspecies of Uca pugilator.

Regulation of the release of chromatophorotropic neurohormones from the isolated eyestalk of the fiddler crab, uca pugilator

Abstract: Electrical stimulation of the isolated eyestalk of Uca pugilator induces the release of several peptides which affect epidermal chromatophores. Thresholds for release of these peptides were different, that for red pigment concentrating hormone (RPCH) being lowest, for black pigment dispersing hormone (BPDH) highest, and for black pigment concentrating hormone (BPCH) intermediate, but no red pigment dispersing hormone(RPDH) was detected at any voltage. Neurotransmitters, known to be present in crustacean central nervous systems, induced chromatophore dose dependent responses. Norepinephrine induced BPDH release, and dopamine induced both RPCH and BPCH release.