Calcification in the Shore Crab, Carcinus Maenas (L.): pH and the Precipitation of Carbonate From Sea Water and Blood

1984 ◽  
Vol 64 (1) ◽  
pp. 233-248 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Local Formation ◽  
Mixed Composition ◽  
Blood Ph ◽  
Water Ph ◽  
Dilute Suspensions ◽  
Series Of Experiments ◽  
The Mean

Much evidence has suggested that calcification in Carcinus and certain other marine organisms may arise at least partly by the local formation of base. The extent of changes of pH needed to precipitate calcium carbonate from sea water or from the blood of the crab are not known with certainty. These have been investigated, using sea water and crabs from the coast of Maine.Mean sea water pH, mostly as measured in aerated samples used for experiments in the laboratory, was 8·00, a little below the values commonly found close to the shore in summer. The corresponding mean blood pH was 7·12. Crushing calcified crab cuticle in sea-water raised the pH, showing the sea water to be below saturation with the salts concerned. The rise in pH was slightly greater in the more dilute suspensions, an effect attributed to the mixed composition of the calcifying salts. Thus in one group of experiments cuticle crushed in sea water in proportions 1:20 and 112·7 raised its pH by 0·66 and 0·62 units respectively, and extrapolation suggested that interstitial fluid of almost zero volume would equilibrate at 0·38 pH units above sea water. Crushing cuticle in crab blood in proportion 1:2·7 raised its pH by 1·03 units, showing the plasma also to be unsaturated with carbonate.Carbonates were precipitated from sea water by rendering it alkaline with sodium hydroxide; in four experiments the first crystallites were found in samples in which in 3 days after addition of base pH had fallen to between 8·46 and 9·30. In a longer series of experiments with crab plasma, crystals were first seen in samples in which after three days the mean pH had fallen to 8–09. Crystallites at the surface formed mosaics of spherulites closely resembling those of normal crab cuticle.

Zinc Regulation in the Lobster Homarus Gammarus: Importance of Different Pathways of Absorption and Excretion

1986 ◽  
Vol 66 (1) ◽  
pp. 175-199 ◽  
Author(s):  
G. W. Bryan ◽  
L. G. Hummerstone ◽  
Eileen Ward
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
The Body ◽  
Shore Crab ◽  
Freshwater Crayfish ◽  
Uptake Mechanism ◽  
Major Pathway ◽  
Homarus Gammarus ◽  
Wide Range ◽  
Body Concentration

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish, Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crab Carcinus maenas losses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobster Homarus gammarus (formerly H. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.

Reducing Activity and the Formation of Base in the Shore Crab, Carcinus Maenas

1985 ◽  
Vol 65 (2) ◽  
pp. 505-530 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Outer Surface ◽  
Biological Material ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Water Salinity ◽  
Shore Crab ◽  
Calcareous Deposits ◽  
Reducing Activity ◽  
Diffusion Potentials ◽  
Active Processes

Crustacean cuticle consists essentially of chitin impregnated and coated with protein which is tanned with quinone (Dennell, 1947a). The outer surface is most heavily tanned, and the cuticle is further strengthened by calcification. The various theories as to the mechanism of calcification in crustacean and other biological material have been reviewed briefly by Digby (1967). Most appear unsatisfactory for various reasons, and evidence was outlined that calcification might arise from the formation of base by processes which are essentially electrochemical in origin. The quinone-tanned protein of the cuticle is electrically semiconducting and supports electrode action in suitable gradients of potential (Digby, 1965), and small potential differences may arise by diffusion or by active processes. Thus the deposition of calcareous salts might arise partly at least by action comparable to that which takes place at a metallic cathode. In support of this, the position of the initial calcareous deposits in Carcinus maenas (L.) was found to change with the gradient of sea-water salinity in the manner expected if some control were exercised by diffusion potentials, acting across a thin semiconducting layer to generate small changes of pH (Digby, 1968).

Suspension feeding in larval crabs (Carcinus maenas)

1993 ◽  
Vol 73 (1) ◽  
pp. 207-211 ◽  
Author(s):  
Jan Robert Factor ◽  
Barbara L. Dexter
Keyword(s):  
Size Range ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Epifluorescence Microscopy ◽  
Shore Crab ◽  
Suspension Feeding ◽  
Natural Diet ◽  
Crab Larvae ◽  
Water Suspensions ◽  
Detrital Particles

First-stage zoeal larvae of the green (shore) crab, Carcinus maenas (Crustacea: Brachyura: Portunidae), ingested three types of particles offered in sea-water suspensions. In experiments using two types of fluorescent particles (1–2 µm and 1–7 µm ) and living Dunaliella tertiolecta cells (5–7 µm), particles were ingested in at least 40% of the zoeae examined with brightfield, darkfield, and epifluorescence microscopy. These results suggest that green crab larvae may be capable of utilizing planktonic particles in the size range of bacteria, small algal cells, and organically-enriched detrital particles in their natural diet.

The Physiology of the Antennal Gland of Carcinus Maenas (L.)

1969 ◽  
Vol 51 (1) ◽  
pp. 11-16
Author(s):  
R. BINNS
Keyword(s):  
Body Weight ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Urine Flow ◽  
The Body ◽  
Antennal Gland ◽  
Urine Production ◽  
The Mean ◽  
Gland Function ◽  
Water Clearance

1. The space measured by inulin distribution, the ‘inulin volume’, has been determined, and represents approximately 20% of the body weight in crabs ranging in size from 20.0 to 57.2 g. 2. After the injection of labelled inulin into crabs, the increase in activity of the medium is equal to the fall in blood inulin in all dilutions of sea water. Clearance of inulin from the blood is due only to urine production, and therefore the molecule can be used for quantitative investigations of antennal gland function. 3. Urine production in various concentrations of sea water has been determined by measuring the clearance of inulin from the blood and the rates at which the tracer appeared in the external media. By these methods the mean rate of urine production in 100% sea water was estimated to be 4.4% body weight per day. In dilute sea water the rate of urine production increases; for example, in 50% sea water the urine flow is four times greater than in normal sea water.

Respiratory and Circulatory Adjustments during Aquatic Treadmill Exercise in the European Shore Crab Carcinus Maenas

1992 ◽  
Vol 162 (1) ◽  
pp. 37-54 ◽  
Author(s):  
N. M. HAMILTON ◽  
D. F. HOULIHAN
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Fold Increase ◽  
Co2 Exchange ◽  
Total Carbon ◽  
Shore Crab ◽  
Rate Of Oxygen Consumption ◽  
Novel Design ◽  
Cardiac Stroke Volume ◽  
Aquatic Treadmill

Carcinus maenas (L.) were exercised using a novel design of aquatic treadmill respirometer. Tethered exercise was performed in sea water at 5.8 m min−1 for 5min. The rate of oxygen consumption and the heart and scaphognathite beat rates increased at the onset of exercise, reaching a steady state within 180 s. The estimated haemolymph flow rate rose 2.6-fold during exercise, achieved by a 1.8-fold increase in heart rate and a 1.5-fold increase in the estimated cardiac stroke volume. The haemolymph total oxygen content difference increased significantly during exercise. Haemolymph total carbon dioxide content did not change significantly during exerise, but haemolymph pH deceased as a result of an L-lactate-induced metabolic acidosis. The acidosis may also have led to a reduced Bohr shift. It is concluded that O2 and CO2 exchange were not impaired during exercise and that C. maenas relied primarily upon O2 to fuel underwater running at 5.8 m min−1.

Adduction Levers and Adductor Muscle Function in the Mandibular System of the Shore Crab Carcinus Maenas

1986 ◽  
Vol 125 (1) ◽  
pp. 309-318
Author(s):  
N. J. Abby-Kalio ◽  
G. F. Warner
Keyword(s):  
Carcinus Maenas ◽  
Adductor Muscle ◽  
Large Male ◽  
Maximum Force ◽  
Shore Crab ◽  
Mechanical Advantage ◽  
Adductor Muscles ◽  
Failure Point ◽  
The Mean ◽  
And Function

The lever systems, and structure and function of the adductor muscles, of the mandibles of large male Carcinus tnaenas (L.) were investigated. The functional mechanical advantage (FMA) of the external adductor muscles, measured at the middle of the biting edge of the mandible, was 1.53 ± 0.01; the ideal mechanical advantage (IMA), calculated from measured lever lengths, was 1.78±0.03 (mean±S.E.). The FMA of the internal adductor muscles was 0.53±0.01 and the IMA was 0.62±0.02. When slowly loaded, the external adductor system broke at 3.09±0.16 N; when rapidly loaded, the system broke at 7.16±0.79 N. Short duration loading at 2.0 N or more was found to result in histologically detectable damage at the pivot. When slowly loaded, the internal adductor system broke at 0.68±0.05 N. When a load of 0.39 N was applied to the internal adductor system, the failure point on slow loading of the external adductor system was not significantly increased. The mean maximum force of contraction of the external adductor muscles on electrical stimulation was 0.98±0.03 N, with a stress of 627kNm−2 in the fibres. The internal adductors contracted with a mean maximum force of 0.33±0.01 N. The total maximum bite force is therefore about 3.3 N, only 10% being contributed by the internal adductors. The safety factor of both internal and external systems is about 2. The mean sarcomere length of half-contracted fibres of the external adductor muscles was 11.62±0.11 μm.

The Effect of Salinity on Cadmium Uptake by the Tissues of the Shore Crab Carcinus Maenas

1977 ◽  
Vol 67 (1) ◽  
pp. 137-146
Author(s):  
D. A. WRIGHT
Keyword(s):  
Sea Water ◽  
Cadmium Concentration ◽  
Carcinus Maenas ◽  
Maximum Level ◽  
Cadmium Accumulation ◽  
Cadmium Uptake ◽  
Whole Body ◽  
Shore Crab ◽  
Salinity Effect ◽  
Wet Weight

Cadmium accumulation by the haemolymph, gills and carapace of the shore crab Carcinus maenas (L.) was significantly higher in dilute sea water. This was reflected in the whole-body cadmium concentrations. There was no salinity effect with the hepatopancreas or muscle cadmium concentration. Over a 68-day period, cadmium was steadily accumulated by the carapace, with the salinity effect becoming increasingly apparent. In 50 % sea water the gill cadmium concentration apparently reached a maximum level after about 2 weeks of uptake. This was eventually overtaken by the tissue cadmium concentration in the gills of 100 % s.w. animals. After about 48 days the salinity effect had disappeared and the gill cadmium concentration of both 50% and 100% s.w. animals (in 20μ-mol Cd l−1 = 2.3 mg l−1) remained at approximately 0.3 μ-mol Cd g−1 (= 33.7 mg kg−1) wet weight of tissue. The hepatopancreas cadmium also levelled off at about this concentration although no salinity effect was apparent. When animals loaded with cadmium for a 37-day period were returned to clean sea water, their whole body cadmium concentration fell by about 50 % after 11 days. Losses from carapace and gills were important components of this reduction in cadmium concentration.

Some observations on concentrically structured, intracellular granules in the hepatopancreas of the shore crab Carcinus maenas (L.)

1979 ◽  
Vol 59 (4) ◽  
pp. 867-877 ◽  
Author(s):  
S. P. Hopkin ◽  
J. A. Nott
Keyword(s):  
Electron Microscope ◽  
B Cells ◽  
Scanning Electron Microscope ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Mean Diameter ◽  
The Mean ◽  
Scanning Electron

The R, F and B cells of the hepatopancreas of Carcinus maenas are derived from undifferentiated (E) cells at the distal end of the tubules. Observations with the scanning electron microscope on freeze fractured tubules show that (a) most of the concentrically structured granules are confined to the R cells with few in F or B cells, (b) within individual R cells, granules are of similar size, and (c) the further R cells are situated from the distal end of the tubule, the greater is the mean diameter of the granules that they contain.

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