Topic
Pachygrapsus
About: Pachygrapsus is a research topic. Over the lifetime, 41 publications have been published within this topic receiving 1180 citations.
Papers
TL;DR: Among species where osmotic regulation occurs, it is established immediately and may be long lasting or may grow weaker with time, and although blood concentrations may fluctuate in a given stress, the phenomenon is not common.
Abstract: 1. The decapod Crustacea, Emerita, Callianassa, Upogebia, Cancer antennarius. C. gracilis and Pugettia cannot regulate osmotically and from lack of tolerance are generally stenohaline.2. Pachygrapsus, Birgus, Hemigrapsus and Uca can regulate osmotically in concentrated and dilute sea water. Hemigrapsus is the weakest hypo-osmotic regulator of the four species.3. Among species where osmotic regulation occurs, it is established immediately and may be long lasting or may grow weaker with time. Although blood concentrations may fluctuate in a given stress, the phenomenon is not common.4. Equilibrium of the blood concentration, where perfect regulation does not occur, is usually established within 24 hours following immersion; changes occasionally occur later when extreme stresses are imposed.5. Estimates on the solute space volumes were calculated as 40% for Emerita, 54% for Pachygrapsus and about 50% for Birgus.6. Concentration changes occurring in the blood of Pachygrapsus and Emerita are caused mostly by s...
154 citations
TL;DR: The ability to regulate in concentrated sea water (hypo-osmotic regulation) is believed to be a manifestation of a mechanism for the conservation of water, namely, elimination of salts.
Abstract: 1. Terrestrial and semi-terrestrial crabs generally demonstrate the ability to regulate osmotically in dilute and concentrated sea water. 2. Osmotic regulation in terrestrial and semi-terrestrial crabs is not adaptive for aquatic life since osmotic stresses such as dilute and concentrated sea water are rarely experienced by these animals. Besides many such animals drown when completely immersed. 3. The branchial chamber of Pachygrapsus contains a volume of fluid equal to a maximum of about 3 per cent of the body volume. Thus, regulation against branchial fluid made concentrated by evaporation would not be adaptive as proposed by Jones because the total salt therein could not elevate the blood concentration above concentrations normally experienced in nature. 4. The respiratory rate of Pachygrapsus decreases when the crab is desiccated. This explains why the terrestrial behavior of Pachygrapsus is limited to brief periods. 5. Pachygrapsus can absorb water against a gradient when it has been desiccated. 6. ...
96 citations
TL;DR: When specimens of Pachygrapsus crassipes were acclimated to 50%, 100% and 170% sea water the average blood osmotic concentrations were equivalent to 0.46, 0.57 and 0.89 normal NaCl, as compared with the medium; the antennary glands may function slightly in hyper-osmotic regulation but not at all in hypo-osMotic regulation.
Abstract: 1. When specimens of Pachygrapsus crassipes were acclimated to 50%, 100% and 170% sea water the average blood osmotic concentrations were equivalent to 0.46, 0.57 and 0.89 normal NaCl, as compared with the medium of 0.29, 0.58 and 0.99, respectively. Urine osmotic concentrations in the same series were equivalent to 0.39, 0.53 and 0.90 normal NaCl.2. Thus the crabs are hyper-osmotic in a dilute medium and hypo-osmotic in a concentrated medium; the antennary glands may function slightly in hyper-osmotic regulation but not at all in hypo-osmotic regulation.3. Serum sodium concentrations in 50, 100 and 170% S.W. were 313, 465 and 668 mM, urine sodium 356, 318 and 264 mM corresponding to environmental concentrations of 229, 459 and 780 mM. Thus as the blood sodium increases the urine sodium decreases.4. The osmotic deficit in the urine is accounted for in part by magnesium which in 50, 100 and 170% S.W. was in blood 9, 29 and 33 mM, in urine 32, 144 and 345 mM while the medium was 26, 52 and 88 mM, respective...
78 citations
TL;DR: There is some correlation between degree of terrestrialness and the ability to hyporegulate, that is, the more terrestrial crabs are stronger Hypo- and hyperosmotic regulation than the more aquatic crabs.
Abstract: 1. In order of their increasing terrestrialness the following seven species of crabs were studied with respect to their osmotic regulatory ability in aqueous media: the aquatic Cancer antennarius, Hemigrapsus oregonensis, the semi-terrestrial Pachygrapsus crassipes, Grapsus grapsus, Ocypode ceratophthalma, Uca crenulata and the terrestrial crab, Gecarcinus lateralis. Cation regulation was studied in all of the above except Ocypode and Grapsus.2. All crabs examined except Cancer showed some degree of hypo- and hyperosmotic regulation. No correlation was found between the strength of hypoosmotic regulation and hyperosmotic regulation.3. There is some correlation between degree of terrestrialness and the ability to hyporegulate. That is, the more terrestrial crabs are stronger hyporegulators than the more aquatic crabs.4. The ratio, urine osmotic concentration/blood osmotic concentration (U/B), for Hemigrapsus, Pachygrapsus, Grapsus, Uca and Ocypode was essentially unity for all treatments. On the basis of c...
72 citations
TL;DR: It appears that predation by shorebirds can sometimes depress the density of small Cerithidea, but its impact is highly variable in space and lime and apparently density-independent.
70 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 1 |
| 2016 | 2 |
| 2015 | 3 |
| 2013 | 1 |
| 2011 | 2 |
| 2009 | 1 |