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Showing papers on "Uca pugilator published in 1982"


Journal ArticleDOI
TL;DR: Uca pugilator, the sand fiddler crab, constructs two kinds of burrows in protected, sandy upper-intertidal and supratidal substrates on the west coast of Florida as discussed by the authors.

150 citations


Journal ArticleDOI
TL;DR: The fiddler crab, Uca pugilator, will survive several intermolt cycles in the laboratory, but the cycles are irregular and variations in cycles are due to variations in the length of stage C4.
Abstract: 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 a...

77 citations


Journal ArticleDOI
TL;DR: Results suggest that maximization of food intake by sand fiddlers occurs at the habitat patch level rather than at the level of particle ingestion, and that inert particles which were ingested with high efficiencies did not stimulate crab feeding.

64 citations


Journal ArticleDOI
TL;DR: Particle extraction efficiencies correlate well with the number of spoon-tipped hairs found on the second maxillipeds of the investigated crab species, implying that these setal types are an adaptation to foraging on sandy sediments, and several lines of evidence are adduced to show that mouth part adaptations are probably not responsible for the exclusion of U. pugnax and U. minax from microhabitat distributions.

53 citations


Journal ArticleDOI
TL;DR: The most striking effect of these drugs was that they strongly reduced the amount of melanin dispersion that normally results on transferring the crabs from a white to a black background.
Abstract: 1. 1. The effects on the melanophores of the fiddler crab, Uca pugilator, of the amine depletor reserpine, the catecholamine neurotoxin 6-hydroxydopamine and the noradrenergic neuron blocker bretylium were investigated. 2. 2. The most striking effect of these drugs was that they strongly reduced the amount of melanin dispersion that normally results on transferring the crabs from a white to a black background. The drugs had no effect on pigment migration in melanophores of isolated legs. These results are in accord with the hypothesis that norepinephrine serves as a neurotransmitter stimulating release of a melanin-dispersing hormone in Uca pugilator. 3. 3. Norepinephrine was found in the central nervous system of Uca pugilator.

17 citations


Journal ArticleDOI
TL;DR: The data obtained with 5-HT and DA agonists and antagonists on red pigment translocation in vivo and in vitro, are consistent with their neurotransmitter candidacies in evoking the release of these erythrophorotropic hormones.

12 citations


Journal ArticleDOI
TL;DR: It is concluded that the Na+ uptake mechanism is activated by decreasing the hemolymph Na+ concentration and that a brain hormone mediates the effect.
Abstract: The hemolymph ionic composition and unidirectional Na+ fluxes were analyzed in fiddler crabs (Uca) acclimated to 500 mosmol seawater. Eyestalkless crabs had lower hemolymph osmotic, Na+, and Cl- concentrations. The Na+ efflux was increased from 13.6 +/- 0.6 in control crabs to 19.6 +/- 1.3 mueq.g-1.h-1 in eyestalkless crabs; this increase was shown to be due to a higher Na+ permeability in eyestalkless crabs. Hemolymph Na+ in eyestalkless crabs was increased by an injection of eyestalk extract. The Na+ influx was increased from 11.1 in intact to 15.8 mueq.g-1.h-1 in eyestalkless animals. A kinetic study showed that 1) the influx was higher at all external Na+ concentrations in eyestalkless and intact-Na+-depleted crabs than in intact controls, and 2) the influx mechanism exhibited allosterism. The elevated Na+ influx in eyestalkless crabs was decreased by an injected eyestalk extract. An injected brain extract caused in increase in the Na+ influx in intact animals. It is concluded that the Na+ uptake mechanism is activated by decreasing the hemolymph Na+ concentration and that a brain hormone mediates the effect.

11 citations


Journal ArticleDOI
TL;DR: The results are consistent with the hypothesis that presynaptic adrenoceptors very similar to alpha2 adrenoception of mammals regulate impulse-mediated norepinephrinergic neurotransmission in the fiddler crab Uca pugilator, nore Pinepinephrine triggering release of a melanin-dispersing hormone.
Abstract: 1. The specific alpha2 adrenoceptor agonist B-HT 933 significantly reduced the rate of melanin dispersion in crabs transferred from a white to a black background. 2. The specific alpha2 adrenoceptor blockers rauwolscine and yohimbine significantly increased the rate of melanin dispersion in crabs transferred from a white to a black background. 3. Rauwolscine and yohimbine, but not the alpha, adrenoceptor blocker indoramin, antagonized B-HT 933. 4. In crabs pretreated with the catecholaminergic neurotoxin 6-hydroxydopamine, which inhibits melanin dispersion, B-HT 933 did not produce further significant inhibition in the rate of melanin dispersion. 5. None of the drugs has been found to affect melanin migration in melanophores of isolated legs. 6. The results are consistent with the hypothesis that presynaptic adrenoceptors very similar to alpha2 adrenoceptors of mammals regulate impulse-mediated norepinephrinergic neurotransmission in the fiddler crab Uca pugilator, norepinephrine triggering release of a melanin-dispersing hormone.

11 citations


Journal ArticleDOI
TL;DR: An increase in temperature and a decrease in salinity sharply increased trimethyltin toxicity in fiddler crab zoeae.
Abstract: The toxicity of four trimethyltin concentrations to stage I zoeae of the fiddler crab,Uca pugilator, was tested at temperatures of 10°C, 20°C and 28°C and salinities of 10‰, 20‰ and 30‰. Stepwise multiple regression of the probit of mortality data produced a formula from which productive response surfaces were generated. 24 hr LC 50's in 30‰ salinity at 10°C was 12 ppm, at 20°C 3.35 ppm and 0.61 ppm at 28°C. Corresponding 48 hr LC 50's were about one-tenth of these values. An increase in temperature and a decrease in salinity sharply increased trimethyltin toxicity in fiddler crab zoeae.

10 citations


Journal ArticleDOI
TL;DR: The extensor muscle and chela of unoperated and transplanted regenerated limbs from two species of Uca were examined to test the theory of neurotrophic control on crustacean muscle, finding that innervation alone controls the growth and differentiation of muscle.
Abstract: The extensor muscle and chela of unoperated and transplanted regenerated limbs from two species of Uca were examined to test the theory of neurotrophic control on crustacean muscle. Initially, tuberculation patterns, sensory hair number, and claw shape of the transplanted regenerated limb resembled those of the donor. Sarcomere lengths were donorlike except when the transplant was from male to female. Eventually the transplanted regenerated limb acquired some recipientlike features, although the claw shape and sarcomere length measurements of secondary regenerates resembled those of the donor. Because of these findings, it is no longer possible to hypothesize that innervation alone controls the growth and differentiation of muscle.

7 citations


Journal ArticleDOI
TL;DR: In this article, the authors found that histamine (HA) is a stimulator of H1 and H2 receptors, which produced dose-dependent inhibition of the melanin dispersion which normally occurs when fiddler crabs, Uca pugilator, are transferred from a white to a black background.
Abstract: Histamine (HA), a stimulator of H1 and H2 receptors, produced dose-dependent inhibition of the melanin dispersion which normally occurs when fiddler crabs, Uca pugilator, are transferred from a white to a black background. The HA precursor L-histidine, and 4-methyl histamine (4-MeHA), an H2 receptor agonist, also inhibited melanin dispersion. 2-Methyl histamine (2-MeHA), an H1 receptor agonist, enhanced melanin dispersion. The inhibitory effects of HA and 4-MeHA were abolished by the H2 receptor blocker metiamide but not by blockers of either H1 receptors or alpha1 adrenoceptors. Melanin-dispersing hormone (MDH) release is accomplished mainly by stimulation of alpha1 adrenoceptors with norepinephrine appearing to be the neurotransmitter involved. The H1 receptor blockers pyrilamine and SA-97 antagonized 2-MeHA. HA-induced inhibition of melanin dispersion was potentiated by the noradrenergic neuron blocker bretylium and the alpha2 adrenoceptor agonist B-HT 933. HA did not significantly affect melanin dispe...

Journal ArticleDOI
TL;DR: The results are consistent with the hypotheses that norepinephrine produces melanin dispersion in Uca pugilator by triggering release of melanin-dispersing hormone (MDH) and when fiddler crabs are transferred from a white to a black background α1 adrenoceptor activation plays the dominant role in executing the MDH-release triggering action of norpineprhine.

Book ChapterDOI
01 Jan 1982
TL;DR: This chapter discusses the osmoregulation in the euryhaline fiddler crab, Uca pugilator, where the cells show typical structures of a salt transporting epithelium like deep basal and remarkable apikal infoldings of the plasma membranes.
Abstract: Publisher Summary This chapter discusses the osmoregulation in the euryhaline fiddler crab, Uca pugilator. The Uca pugilator is a good hyperosmotic regulator in diluted sea water and in a more limited range also a hypoosmotic regulator in concentrated sea water. It is well documented that in decapode crustacea, the gills take the main part in hyperosmotic extracellular regulation. There are evidences that sodium extrusion in hyperosmotic medium takes place in the gills. In the posterior gills of animals adapted to normal sea water, the specific activity of ATPase is 2.5–5 times higher as in the anterior gills. The specific activity of succinicdehydrogenase does not increase in the posterior gills whereas in the anterior gills, it is actually diminished significantly. This may be because of the fact that the protein is increased. In concentrated medium, a tendency of decrease of both enzyme activities is noticed. Light and electron microscopic studies prove that the anterior gills have a thin single-layered epithelium with few cell organelles and poorly differentiated membranes. The cells show typical structures of a salt transporting epithelium like deep basal and remarkable apikal infoldings of the plasma membranes.

Book ChapterDOI
01 Jan 1982
TL;DR: This chapter focuses on the influence of acclimation temperature upon the pattern of phospholipids, fatty acids, and sterol content of the fiddler crab Uca pugilator.
Abstract: Publisher Summary This chapter focuses on the influence of acclimation temperature upon the pattern of phospholipids, fatty acids, and sterol content of the fiddler crab Uca pugilator. The common fiddler crab Uca pugilator is distributed over the eastern and southern coast line of the United States from Cape Cod in the north to the Gulf Coast in the south. As a semiterrestric species, it is also subjected to sudden changes in temperature in its habitat, and to daily and seasonal thermal fluctuations. The main phospholipid components in the membrane fraction are phosphatidylcholine (PC) and phosphatidyethanol-amine (PE). The fatty acid composition of the individual phospholipid classes does not differ remarkably in cold and warm adapted animals.

01 Jan 1982
TL;DR: Histamine (HA), a stimulator of H1 and H2 receptors, produced dose-dependent inhibition of the melanin dispersion which normally occurs when fiddler crabs, Uca pugilator, are transferred from a white to a black background.
Abstract: Histamine (HA), a stimulator of H1 and H2 receptors, produced dose-dependent inhibition of the melanin dispersion which normally occurs when fiddler crabs, Uca pugilator, are transferred from a white to a black background. The HA precursor L-histidine, and 4-methyl histamine (4-MeHA), an H2 receptor agonist, also in hibited melanin dispersion. 2-Methyl histamine (2-MeHA), an H1 receptor agonist, enhanced melanin dispersion. The inhibitory effects of HA and 4-MeHA were abolished by the H2 receptor blocker metiamide but not by blockers of either H1 receptors or alpha1 adrenoceptors. Melanin-dispersing hormone (MDH) release is accomplished mainly by stimulation of alpha1 adrenoceptors with norepinephrine appearing to be the neurotransmitter involved. The H1 receptor blockers pyrilamine and SA-97 antagonized 2-MeHA. HA-induced inhibition of melanin dispersion was potentiated by the noradrenergic neuron blocker bretylium and the alpha2 adrenoceptor agonist B-HT 933. HA did not significantly affect melanin dispersion in crabs pretreated with 6-hydroxydopamine which destroys catecholaminergic neuroterminals. None of these drugs affected the melanophores directly. On the basis of these and previously obtained results it is suggested that H1and H2receptors are present on norepinephrine neurons involved in triggering MDH secretion, and administered HA inhibits MDH release by decreasing impulse-mediated norad renergic neurotransmission through stimulation of H2 receptors.