bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and function in the excretory systems of some terrestrial prosobranch snails (Cyclophoridae)
Authors: Andrews Elizabeth B. , Little Colin 
Published: August 2009

The excretory systems of terrestrial prosobranch snails of the family Cyclophoridae, collected in Jamaica, Costa Rica and South Africa, have been examined physiologically and as regards their gross and fine structure. The process of urine formation commences in the heart, where fluid is filtered across the wall of the ventricle. Filtration through the auricular wall is believed to be negligible. The kidney, which contains three types of cell, modifies the composition of the filtrate. One type of resorptive cell, characterized by basal infoldings associated with mitochondria, takes up salts. Another type, with basal subcellular spaces, may be responsible for taking up water. The third type of cell is secretory, producing concretions of uric acid and phospholipid which are liberated into the kidney lumen when the cell degenerates.The rate and mechanism of urine production have been investigated using injections of inulin. The filtration rate at 25°C is 0.5 μl/g/min, and in 100% R.H. the average rate of urine production is 0–39 μl/g/min.An accessory excretory organ has been developed from the hypobranchial gland of aquatic forms. It is composed of groups of subepithelial tubular glands opening into the mantle cavity by one or a series of pores, and secreting purines, phospholipids and mucus. There is evidence that this organ becomes progressively more complex in forms occupying drier habitats.The systems of excretion and osmoregulation in the Cyclophoridae are considered to be very similar to those in their aquatic relatives, the Viviparidae and Ampullariidae. Certainly the cyclophorids are not as well adapted to a terrestrial life as are the Pulmonata, and in many respects they may be considered “aquatic” snails living on land.
Latitudinal variation in associations of planktonic Rotifera
Authors: Green J. 
Published: August 2009

The planktonic Rotifera are not all cosmopolitan in their geographical distribution. There is a latitudinal variation in the assemblage of planktonic species. Most of this variation can be attributed to species in nine genera, of which some (e.g. Brachionus) are more abundant in warm areas, and others are more abundant in cool areas (e.g. Notholca). The latitudinal change in the assemblage is gradual, but it can be measured by the Sorensen index of similarity.In addition to the latitudinal variation there is evidence of a small group of species restricted to the Americas.Detailed surveys extending over a year or more yield between 30 and 100 species for a given lake or area, except in the high Arctic where the number recorded for Spitzbergen falls to 16. Single samples yield many fewer species, normally ranging from 4 to 26.
Indications of recent changes in status in the British Isles of the frog (Rana temporaraia) and the toad (Bufo bufo)
Authors: Cooke A. S. 
Published: August 2009

Two surveys are described which were designed to provide information on changes in status in the British Isles of the frog (Rana temporaria L.) and the toad (Bufo bufo L.). Questionnaires were distributed asking for information and conclusions are based on replies referring to 1079 localities and 314 individual breeding sites. Replies indicated that the frog decreased slightly over most of the British Isles during the 1940s and 1950s, and suffered considerable declines over most of England throughout the 1960s. Moderate declines occurred in Scotland and Northern Ireland during the last half of the decade. Declines for the toad probably followed a similar pattern.The garden pond was the only habitat in which either species increased. Both the frog and the toad decreased markedly in breeding sites on agricultural land in the early 1960s, but during the late 1960s declines were less severe.The main reason for the declines has probably been loss of suitable wetland habitat due to sites being filled in, drained or physically modified in some way. Insecticides are only likely to have been harmful in sites where unusually high pollutant concentrations occurred. Other possible contributory factors are discussed and of these road mortality is perhaps the most important. Recent declines for the frog were significantly related to human population density.
Locomotory aspects of squid mantle structure
Authors: Ward Diana Valiela , Wainwright Stephen A. 
Published: August 2009

Morphological aspects of squid (Loligo, Lolliguncula) mantle relevant to locomotory function were studied. Methods used included polarized light microscopy of frozen sections of untreated tissue taken from animals immediately after death and electron microscopy.The mantle consists of circular and radial muscles arranged in alternating rings along the whole length of the mantle. The muscle is obliquely striated. Connective tissue fibres are found in the body of the muscle and in the outer and inner tunics. The outer tunic consists of layers of large collagenous fibres. The fibres run in superimposed right‐ and left‐handed helical courses that lie at an angle of 27° to the long axis of the animal. The tunics and the intramuscular connective fibres are thought to resist length changes in the mantle while permitting the changes in girth required for the jet power stroke. Both the intramuscular and the tunic fibre systems may provide elastic energy for the return phase of the jet cycle. Tunic fibres appear to be a geodesic tensile reinforcing system ensuring smooth shape changes in the mantle.
The food of feral mink (Mustela vison) in Scotland
Authors: Akande Modupe 
Published: August 2009

Feral American mink (Mustela vison) thrive in Scotland. The potential impact of the mink on the native fauna was investigated through its food. Fifty‐five stomachs and 33 scats were analysed by identifying the indigestible remains. Fish formed the main prey (49% occurrence) and birds and mammals 28% and 23% respectively. Most of the fish eaten were Salmonidae (brown trout and salmon). No remains of eels were found.Mink may compete with otters for food, but the smaller prey taken by the mink and its greater use of land separates it from the otter. Mink seem to be occupying a vacant feeding niche in Scotland.
Locomotory function of the squid mantle
Authors: Ward Diana Valiela 
Published: August 2009

A detailed kinematic analysis of the mantle movements of swimmingLolliguncula breviswas made. Some data were also obtained onLoligo pealei.The qualitative and quantitative data provided are of use in discussing mechanisms of squid mantle function.Several possible mechanisms of squid mantle re‐expansion were proposed and investigated. The inhalant phase of jet propulsion is probably effected by contraction of the radial muscles, since thinning of the mantle wall accompanies re‐expansion. The radial muscles may cause mantle re‐expansion by contracting alternately with the circular muscles in response to nerve impulses, or by contracting alternately with the circular muscles in response to stretch cycles effected by mantle wall thickening in the power stroke, or by contracting continuously through both power and recovery strokes. Elasticity of the mantle tissue may contribute to mantle re‐expansion. Neither pressure pumps nor a Bernoulli effect mechanism are effectors of mantle re‐expansion.
Body size and composition of elephant seals (Mirounga leonine): absolute measurements and estimates from bone dimensions
Authors: Bryden M. M. 
Published: August 2009

The major body components (bone, muscle, blubber, viscera and connective tissue) of 94 elephant seals were dissected and weighed.Seals in growth phase 3 (more than ten weeks old) had significantly more muscle and viscera and less blubber than seals in growth phases 1 and 2 (less than ten weeks old) of similar body weight. There were no significant differences in body composition between sexes before sexual maturity, but after sexual maturity was attained males had relatively more muscle, and less bone and viscera, than females.Prediction equations relating body component weight and body weight were derived by regression analysis. These were very highly significant, and could be used to estimate body composition from body weight.It was demonstrated that body length could be estimated from linear measurements of some bones, which would enable an estimate of size and composition of seals to be made from bone dimensions.
The true body shape of rorqual whales
Authors: Williamson Gordon R. 
Published: August 2009

Live Sei and Minke whales were observed underwater off Japan by a new method using commercial catcher boats. A non‐explosive harpoon was fired into the tail region of a whale and a diver approached the “tethered” live whale.After initial flurries, Sei and Minke whales swam steadily ahead of the catcher and could easily be approached by a diver. They took absolutely no notice of the diver. Live Sei and Minke whales kept their mouths tight shut all the time, but immediately after death the lower jaw always fell open. Little blood was emitted from the harpoon wound. The flippers were raised laterally when a whale surfaced and held against the sides of the body when it dived.The body shape of both rorqual species was streamlined and the throat region was quite flat, not in any way dilated. The classical baggy‐throated illustrations of rorqual whales do not show the true shape of live animals.Sperm whales harpooned by the same method swam about wildly, shed much blood and could not be observed underwater.
Flight muscle hypertrophy and ecophysiological variation of Yellow wagtail Motacilla flava races at Lake Chad
Authors: Fry C. H. , Ferguson‐Lees I. J. , Dowsett R. J. 
Published: August 2009

During the few days before emigration to the Palaearctic, the weight of Yellow wagtails wintering in Africa doubles. Most of the increase is due to the deposition of fat, as is well known, but a part of it is shown to result from hypertrophy of the pectoral muscles. The same applies to other Palaearctic birds, four warblers and a hirundine, that winter in Africa.Eleven subspecies of M. flava occur at Lake Chad in spring. The four black‐headed ones have more restricted habitat requirements than some of the others; however, no differences in diet have been found. There is no evidence of hyperphagia and little of diet change when fattening. Broadly, the races that have farthest to migrate leave earliest, and their sexual recrudescence and fattening are early.Yellow wagtails wintering at or passing through Lake Chad breed mainly in eastern Europe (from the Adriatic to the Gulf of Finland, between about 12° and 30°E). They probably migrate on a great circle route, and during the flight lose one gram of weight, mainly fat, per 200 km.
Histochemical and ultrastructural observations on feeding and digestion in Reighardia sternae (Pentastomida: Cephalobaenida)
Authors: Riley J. 
Published: August 2009

Histological, histochemical and ultrastructural methods have been used to study gut structure and function in the cephalobaenid pentastomid Reighardia sternae (Diesing, 1864). R. sternae feeds exclusively on blood. Haemolysis of ingested erythrocytes is thought to be initiated by non‐specific esterase secreted by cells lining the posterior oesophagus. Only one other enzyme, acid phosphatase, was demonstrated; its activity is confined to the microvillar layer of the gastrodermis.Digestion appears to be largely extracellular, as large volumes of haematin form in the gut lumen after haemolysis. However, this is supplemented by a significant amount of intracellular digestion: accumulations of iron‐positive granules occur in approximately 20% of gastrodermal cells.All gastrodermal cells are alike, and all can undertake the same intracellular digestive process. This is characterized by a number of morphologically distinct stages which have been studied using the electron microscope. The iron‐positive particles distinguished under the light microscope were easily identifiable ultrastructurally. Spherical, weakly iron‐positive bodies form within the cisternae of the endoplasmic reticulum. Phagosomes containing haemoglobin, or some breakdown product of haemoglobin, apparently bud off from the termini of a labyrinth system of tubules under the microvilli and fuse with the ER to form these phago‐lysosomes. Intensely iron‐positive heterolysosomes, also present in the cytoplasm of these cells, accumulate haemosiderin particles which are thought to be released into the cytoplasm during phago‐lysosomal digestion.The ensuing complex changes in cell morphology are, apparently, related to the elimination of spent phago‐lysosomes. It has been suggested that the purpose of intracellular digestion is to provide a specific metabolite which the extracellular degradation of haemoglobin cannot supply.
Decapod Crustacea from the International Indian Ocean Expedition: the larval development of Heterocarpus (Caridea)
Authors: Menon P. Gopala 
Published: August 2009

The larval species Atlantocaris gigas Ortmann is shown to be conspecific with Heterocarpus ensifer A. Milne Edwards, while Procletes biangulatus Bate is the larva of Heterocarpus levicarina (Bate). Each species passes through 13–15 zoeal stages and 3–4 megalopal stages. The later zoeal stages are large, have a long toothed rostrum, a carinated carapace and dorsal abdominal spines. The carinae on the carapace are retained in the adult; the rostrum becomes shortened and the abdominal spines modified at metamorphosis. Larval characters support the retention of Heterocarpus in the Pandalidae.New information on the distribution of both species is included.
The food of the Common frog, Rana temporaria, on high moorland in northern England
Authors: Houston W. W. K. 
Published: August 2009

Analysis of the stomach contents of 427 Common frogs, Rana temporaria L., captured on an area of moorland typical of the northern Pennines, showed that this species is an unspecialized and opportunistic feeder in this habitat.There was a distinct temporal variation in the food eaten which was closely related to its availability. Adult Tipulidae and Lepidoptera larvae each formed a fifth of the diet by volume, while Phalangidae, Coleoptera, and Gastropoda, each formed about a tenth. The diet of the frogs changes as they grow. Small frogs fed almost entirely on small items. The bigger the frog the wider the range of items eaten and the larger the items which were predominantly eaten.
Feeding and gut structure in Nerilla antennata (Annelida: Archiannelida)
Authors: Gelder S. R. , Uglow R. F. 
Published: August 2009

The littoral and sublittoral marine archiannelid Nerilla antennata Schmidt 1848 browses selectively on organic debris and micro‐organisms (algae, protozoa and bacteria) resident on the substrata. The gut consists of a mouth, a buccal cavity with a posteriorly‐situated muscular pharynx, a proventriculus, stomach, intestine and anus. The alimentary canal is ciliated throughout its length, except for the muscular pharynx. The selected food is abraded and fragmented by the “to and fro” action of the muscular pharynx and this organ, aided by the anterior, ventral ciliary sheet, directs the food into the buccal cavity. Mucus from the posterior lips of the mouth and granules from the salivary glands are mixed with the food particles as these are concentrated in the proventriculus. The particles are then drawn, by a peristaltic wave, into the stomach. Regurgitation is prevented by posteriorly‐directed cilia which line the constriction separating the proventriculus from the stomach.The stomach wall consists of cells which vary in shape from columnar (25 μm in height) to cuboidal (12 pm) and there is an anterior ring of strongly basophilic cells surrounding the entrance of the proventriculus into the stomach. The distal regions of these cells contain numerous proteinaceous granules and bear a somewhat reduced number of cilia.Pyriform gland cells occur laterally beneath the cells of the stomach wall. Their necks penetrate between the sharply delineated stomach wall cells, to discharge a proteinaceous mucoid material into the gut lumen. Sections of the stomach stained with toluidene blue differentiated two types of non‐glandular cells, one positively staining and the other negative ly staining. The anterior stomach contains a predominance of negatively‐staining cells, whilst posteriorly the proportion of positively staining cells increases until they form a ring surrounding the posterior stomach lumen.Lipid droplets were localised mainly in the epidermis and in the walls of the stomach and intestine. Following a short period of starvation a lowered concentration of lipid droplets in the distal region of the stomach and intestinal cells was noted.
The feeding mechanism and ecology of the New Zealand pulmonate limpet, Gadinalea nivea
Authors: Walsby J. R. , Morton J. E. , Croxall J. P. 
Published: August 2009

Gadinalea nivea is a marine pulmonate classed near the Siphonariidae. It lives at mid‐tidal level under ledges and in small concavities, away from light, on rocky shores exposed to heavy surge, or in caves with high water turbulence. Gadinalea does not normally move about, but lives in closely aggregated colonies. In the absence of light, algal food is scarce and the animal does not in the normal way abrade the substratum with the radula.The feeding mechanism involves the utilization of the turbulence of the water, and the animal orients very accurately to the current. In its normal position it hangs upside‐down, and lowers the shell, so that the water current enters behind. Lavish mucus is produced from glands of the mantle edge and the sides of the foot. A mucous curtain is so secreted, in front of the head, extending outwards from the mantle margin and ballooning out with the current from behind. Particles of phytoplankton are in this way trapped until the mucous curtain is fully loaded. At close intervals it is inspected by the extended oral lobes, and is then enclosed by a hood formed by these lobes, and ingested.There are no ciliary tracts involved in food‐collecting, and normal feeding is not elicited in still water. Animals must be observed under suitable conditions of turbulence for feeding behaviour to appear. Measurements with a “Celloscope” cell counter showed progressive reduction of the particle content of suspensions in which Gadinalea was being fed.The histology of the mantle edge shows highly specialized mucus‐secreting tracts. The structure of the alimentary canal has a basic resemblance to that of the Siphonariidae, but in several features, especially the reduction in size of the radula teeth, has become adapted for current‐borne particle feeding.
Deposit feeding in Abra tenuis (Bivalvia: Tellinacea)
Authors: Hughes T. G. 
Published: August 2009

Deposit feeding in Abra tenuis is described in terms of the size of particles utilized.Material is collected by the inhalant siphon performing a circular motion sucking in sediment from beneath and on the surface.The size distribution of silica admitted into the mantle cavity is described and shown to be controlled by physical parameters. The density of a particle does not affect its uptake by the inhalant siphon. The size distribution of the sediment affects the size distribution of particles admitted to the mantle cavity.No selection of material for ingestion in terms of size occurs after it has been taken into the mantle cavity. Thus the range of material ingested is ultimately controlled by a physical parameter, the inhalant opening.
Histological and ultrastructural studies on the testis of Bithynia tentaculata (Mollusca: Gastropoda), and on the effects of Cercaria helvetica XII (Trematoda: Digenea) on this host organ*
Authors: Reader Trevor A. J. 
Published: August 2009

Histological and ultrastructural studies were made on spermatogenesis in the gastropod mollusc Bithynia tentaculata (L.). The various changes seen during the differentiation of spermatogonia into spermatocytes, spermatids and ultimately spermatozoa, are described, and their significance discussed. The nutrients required by these developing germ cells appear to be furnished by nutritive cells attached to the germinal epithelium. The spermatozoa are highly specialized to facilitate the successful fertilization of ova.In snails heavily infected with sporocysts of the digenetic trematode Cercaria helvetica XII (Dubois), many of the seminiferous tubules were found to be degenerating. The significance and possible causes of this degeneration are discussed.
The functional significance of the spermatophore and the fate of spermatozoa in the genital tract of Helix pomatia (Gastropoda: Stylommatophora)
Authors: Lind Hans 
Published: August 2009

In the Helicidae and in some other Stylommatophora the sperm are transferred in a spermatophore, even though there appears to be no need for protection of the sperm during the transfer. The function of the spermatophore and related problems concerning the genital organs of Helix pomatia were studied by means of morphological and experimental methods.The spermatophore is necessary to ensure the functioning of the female system at copulation. Its structure allows some of the spermatozoa it contains to escape through its tail canal, pass from the stalk of the bursa and reach the spermatheca by way of the oviduct; but most of the sperm pass into the bursa copulatrix and are destroyed, as is also the fate of the spermatophore. Only foreign sperm are stored in the spermatheca.Spermiogenesis was found to take place throughout the whole summer. At intervals some sperm are released from the hermaphrodite duct and are conducted via the spermoviduct and oviduct to the bursa, where they are digested. The two grooves of the spermoviduct are functionally separated only for a few minutes at actual copulation, when sperm are conducted to the copulatory organs, where the spermatophore is being formed.
The dentition and dental tissues of the agamid lizard, Uromastyx
Authors: Cooper J. S. , Poole D. F. G. 
Published: August 2009

The dentition of Uromastyx hardwicki was examined in a series of carefully prepared dry skulls and was found to be very different from that of other agamid lizards. The anatomy of the dentition undergoes great changes from the time of hatching to advanced age, but no evidence of tooth replacement could be found. Extension of the tooth rows by addition of larger teeth posteriorly, together with elongation of the premaxilla, and a characteristic pattern of wear are responsible for the condition seen in aged specimens.The structure of the dental tissues was investigated by means of a variety of histological techniques including scanning electron microscopy and it is established that the enamel has prismatic structure like that of mammalian enamel. The mode of formation of enamel with and without prisms is described and the occurrence and significance of prismatic structure in reptilian dental enamel discussed.