Distribution and zonation of shore crabs in the Pulicat lake

1986 ◽  
Vol 95 (4) ◽  
pp. 437-445 ◽  
Author(s):  
D R Joel ◽  
P J Sanjeeva Raj ◽  
R Raghavan
Keyword(s):  
Pulicat Lake ◽  
Shore Crabs

Noise negatively affects foraging and antipredator behaviour in shore crabs

2013 ◽  
Vol 86 (1) ◽  
pp. 111-118 ◽  
Author(s):  
Matthew A. Wale ◽  
Stephen D. Simpson ◽  
Andrew N. Radford
Keyword(s):  
Antipredator Behaviour ◽  
Shore Crabs

Coxal Muscle Receptors in the Crab: The Receptor Potentials of S and T Fibres in Response to Ramp Stretches

1971 ◽  
Vol 55 (3) ◽  
pp. 813-832
Author(s):  
B. M. H. BUSH ◽  
ALAN ROBERTS
Keyword(s):  
Motor Nerve ◽  
Large Diameter ◽  
Muscle Fibres ◽  
Dynamic Component ◽  
Static Responses ◽  
Basal Joint ◽  
Muscle Receptors ◽  
Shore Crabs ◽  
Static Nature ◽  
Receptor Muscle

1. Intracellular and extracellular recordings from the two large-diameter S and T sensory fibres of the posterior thoracico-coxal muscle receptor in shore crabs confirm the graded, dynamic-static nature of the receptor potentials evoked by stretching the receptor muscle, and the lack of afferent impulses. 2. Slow ramp-function stretches evoke receptor potentials with characteristic shapes, which differ between the two fibres in several respects: (i) The dynamic component in the S fibre resembles an algebraic sum of length and velocity responses and a variable initial ‘acceleration’ (?) transient, while in the T fibre it commonly declines (‘adapts’) during stretching, especially at greater velocities and starting lengths. (ii) On release of stretch the S fibre usually exhibits a ‘negative velocity response’, but the T fibre repolarizes rapidly often with a slight hyperpolarization. (iii) The dynamic response of the T fibre is generally greater than that of the S fibre, and increases more steeply and approximately logarithmically with stretch velocity over a 10- to 50-fold range. (iv) The ‘static response’ or degree of depolarization increases fairly linearly with receptor length in the S fibre but very non-linearly in the T fibre. (v) The T fibre displays pronounced hysteresis in its dynamic and static responses at increasing and decreasing lengths, but the S fibre shows little hysteresis. (vi) The T fibre but not the S fibre commonly shows small rapid oscillations or ‘noise’ superimposed upon strongly depolarized ‘static’ potentials. (vii) The S and T responses may be affected reciprocally by some forms of receptor muscle contraction. 3. Graded receptor potentials evoked in the ‘D’ fibre by stretching the non-muscular depressor-receptor strand of the coxo-basal joint show little hysteresis. 4. Receptor muscle fibres respond to motor nerve stimulation or spontaneous motor impulses from the thoracic ganglion with slow, facilitating and summating excitatory junctional potentials. 5. The mechanisms underlying the differences between S and T responses, and their functional significance to the animal, are discussed, and comparisons are drawn with other muscle receptors.

scholarly journals IV.—Note on a Fossil Crab and a Group of Balani Discovered in Concretions on the Beach at Ormara Headland, Mekran Coast

1905 ◽  
Vol 2 (7) ◽  
pp. 305-310
Author(s):  
Henry Woodward
Keyword(s):  
Posterior Pair ◽  
Dorsal Aspect ◽  
Small Crab ◽  
The Family ◽  
Shore Crabs

Having been desired by my friend Miss Caroline Birley to examine two Crustaceans in nodules from the Mekran Coast— part of a much larger series, mostly enclosing fossil shells, described by Mr. R. B. Newton, F.G.S. (see ante, pp. 293–303)—I gladly comply with the request to add a note thereon to his paper.The first concretion, when broken open, displays the dorsal aspect in impression and counterpart of a small crab, 5½ cm. broad by 3 cm. deep, having one long, slender, forcipated chela, imperfectly preserved, measuring nearly 5 cm. in length; and part of one of the fifth posterior pair of feet, adapted for swimming, showing it to have been near to the family Portunidæ, to which our common shore-crabs of the genus Portunus belong. None of these, however, can be satisfactorily compared with the fossil crab from Ormara, which is certainly referable to another genus.

scholarly journals Long-term change in the parasite burden of shore crabs ( Hemigrapsus oregonensis and Hemigrapsus nudus ) on the northwestern Pacific coast of North America

2021 ◽  
Vol 288 (1945) ◽  
pp. 20203036
Author(s):  
Jessica Quinn ◽  
Sarah Lee ◽  
Duncan Greeley ◽  
Alyssa Gehman ◽  
Armand M. Kuris ◽  
...  
Keyword(s):  
Parasite Burden ◽  
Shore Crab ◽  
Northwestern Pacific ◽  
Intermediate Hosts ◽  
Term Change ◽  
Shore Crabs ◽  
Living Species ◽  
Hemigrapsus Oregonensis ◽  
Over Time

The abundances of free-living species have changed dramatically in recent decades, but little is known about change in the abundance of parasitic species. We investigated whether populations of several parasites have shifted over time in two shore crab hosts, Hemigrapsus oregonensis and Hemigrapsus nudus, by comparing the prevalence and abundance of three parasite taxa in a historical dataset (1969–1970) to contemporary parasite abundance (2018–2020) for hosts collected from 11 intertidal sites located from Oregon, USA, to British Columbia, Canada. Our data suggest that the abundance of the parasitic isopod Portunion conformis has varied around a stable mean for the past 50 years. No change over time was observed for larval acanthocephalans. However, larval microphallid trematodes increased in prevalence over time among H. oregonensis hosts, from a mean of 8.4–61.8% between the historical and contemporary time points. The substantial increase in the prevalence of larval microphallid trematodes could be owing to increased abundances of their bird final hosts, increased production of parasite infective stages by snail intermediate hosts or both. Our study highlights the variability among parasite species in their temporal trajectories of change.

scholarly journals Influence of temperature on intraspecific, unbalanced dyadic contests between crabs

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7845
Author(s):  
Allan T. Souza ◽  
Felipe O. Ribas ◽  
João F. Moura ◽  
Claudia Moreira ◽  
Joana Campos ◽  
...  
Keyword(s):  
Carapace Width ◽  
Carcinus Maenas ◽  
Individual Characteristics ◽  
The Body ◽  
Shore Crab ◽  
Temperature Conditions ◽  
Red Color ◽  
Shore Crabs ◽  
Influence Of Temperature On ◽  
Globally Distributed

Intraspecific agonistic interactions are widespread across the animal kingdom, with many individual morphological and physiological characteristics playing important roles in the fate of disputes. Additionally, changes to environmental conditions can influence the outcomes of animal contests. The shore crab (Carcinus maenas) is a globally distributed species, present in numerous coastal and estuarine temperate systems around the world. Although shore crabs are highly tolerant to changes in temperature, this parameter has important physiological effects on the species’ ecology, while its effects on behavior are not fully understood. Our study aims to investigate how different individual characteristics (such as sex, color morphotype, carapace and chela morphology) and temperature conditions affect the dyadic interactions between shore crabs when disputing food resources. In general, the differences in carapace width between opponents, their sexes, color morphotypes and the temperature conditions interacted and were important predictors of the contest fate. We found that the body size and color morphotype of C. maenas determined the fate of dyadic disputes. However, the higher temperatures disrupted the well-established dominance of the larger red color morphotype individuals. Overall, the agonistic contest results suggest higher plasticity than previously acknowledged.

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