bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tail skin of the dipnoan Neoceratodus larva: fine structure and differentiation
Authors: FOX HAROLD 
Published: March 2009

The fine structure of the tail skin oflarval Neoceratodusforsteri, between stages 40 and 50 (Kemp, 1982), is described and where applicable specific cellular components are compared and contrasted with comparable ones in the skin of adult dipnoans, teleosts and larval and adult amphibians.The epidermis of the early developing tail, within the range studied, differentiates a variety of different cell types. Surface epithelial lucent and vacuolated lucent cells and basal cells are distinguished, and goblet (mucous) cells, Merkel cells and macrophages appear in the epidermis towards the end of the series.Below a poorly developed collagenous basement lamella, immature melanophores with premelanosomes are present, and likewise there are non–myelinated nerves, some striated muscle fibres, capillaries and mesenchymal fibroblasts.The tail epidermis is innervated by naked neurites from the beginning of the series, and the earliest recognizable Merkel cell is in synaptic association with neurites.
Resource partitioning among Odonata (Insecta: Anisoptera and Zygoptera) larvae in a Hong Kong forest stream
Authors: DUDGEON DAVID 
Published: March 2009

Larvae of four odonate species were common in Tai Po Kau Forest Stream, Hong Kong: Euphaea decorata (Zygoptera: Euphaeidae), Zygonyx iris (Anisoptera: Libellulidae), Heliogomphus scorpio and Onychogomphus sinicus (Anisoptera: Gomphidae). All co‐occurred within a single riffle reach and had similar life cycles. Consequently, available dimensions for niche partitioning were likely to have been microhabitat and diet.Across–stream gradients in population density, and the results of multivariate regression analyses of abundance against microhabitat parameters, were similar for all species except Z. iris. This species avoided microsites near the stream banks, and had no significant best–fit regression model predicting abundance. Nevertheless, microhabitat overlaps among all four species were high (Oxy > 0–81). The scale of this investigation (sampling units = 1000 cm2) may have obscured partitioning of space within microsites, because burrowing O. sinicus were unlikely to have occupied the same sediment patches as epibenthic H. scorpio or Z. iris.Dietary overlaps between Z. iris and the other species were low. Heliogomphus scorpio and O. sinicus had the most similar diets of any species–pair, but among these two species intraspecific overlaps between large and small individuals were generally less than interspecific comparisons between equivalent–sized larvae. Ontogenetic dietary shifts and asynchronous larval development in both of these gomphids may have contributed to intraspecific partitioning of food. Euphaea decorata had the broadest niche axes along food and microhabitat dimensions, whereas Z. iris was relatively specialized. Heliogomphus scorpio and O. sinicus made similar use of resources. In the absence of evidence that resources were limiting or depletable, competition could not be invoked as an explanation for niche partitioning. Instead, determination of morphology by phylogeny, and resultant influences on microhabitat selection and foraging behaviour, probably determined patterns of resource use resulting in closely related species showing the greatest niche overlap.
Developmental anatomy of the tailed frog (As cap hits truei): a primitive frog with large eggs and slow development
Authors: BROWN HERBERT A. 
Published: March 2009

The embryonic and early larval development of Ascaphus was studied by culturing embryos at 11 °C. Twenty stages of normal development are morphologically defined by using a standard staging system for anuran amphibians.Cleavage stages are distinctive. The first cell division is unique because two separate furrows develop and then fuse to form a single cleavage plane. The large, yolky cytoplasm continues to influence cell divisions, and a blastula develops with very large vegetal cells and small, irregular shaped animal cells. There is a conspicuous, translucent blastocoel in the late blastula, and during gastrulation this structure is displayed forward by the internal migration of cells. Except for slight differences in proportions, the gastrula and neurula stages resemble the typical anuran pattern. Circulation (stage 20) begins when large vitelline veins develop on the yolk sac and direct the return of blood flow to the heart.At hatching, the tadpole has a large yolk sac, little skin pigmentation, and no gills. Mouthparts and opercular coverings of the branchial arches develop slowly. Hind limb buds develop at the base of the tail, but they are soon concealed as a skin membrane develops and covers these structures.The reproductive strategy for this primitive and highly aquatic frog is unusual: there is a small number of large eggs that develop slowly and produce tadpoles that continue this slow developmental process.
The function of the intramaxillary joint in the Round Island boa, Casarea dussumieri
Authors: CUNDALL DAVID , IRISH FRANCES J. 
Published: March 2009

The bolyeriid snakes Casarea dussumieri and Bolyeria multocarinata are unique among vertebrates in possessing an intramaxillary joint that separates the maxilla into anterior and posterior segments. In contrast to previous studies, which suggest that this joint permits enhanced elevation of the anterior maxillary teeth, our films of live Casarea show that the snout and anterior maxillary teeth are actively depressed 15° 20° below rest position through bilateral retraction of the palatomaxillary arches. Patterns of bone movement in living Casarea support the hypothesis that a caudally directed force is transmitted to the snout via the medial bones of the palatomaxillary arch, suggesting functional affinities between Casarea and higher henophidians.The intramaxillary joint, in conjunction with the curvature of the mandibles, allows the jaws of Casarea to encircle hard, cylindrical prey held transversely in the mouth. Because the Mauritian terrestrial vertebrate fauna lacks mammals and is dominated by skinks and geckos, which Casarea is known to consume, we suggest that the intramaxillary joint functions in a manner analogous to that achieved by quite different maxillary modifications in colubrid scincivores. Although the origin of the bolyeriid intramaxillary joint remains unclear, its structural refinement and evolutionary stability may be due to selection pressures arising from limited prey diversity.
The structure and function of the digestive system of terrestrial isopods
Authors: HAMES C. A. C. , HOPKIN S. P. 
Published: March 2009

The functional morphology of the digestive system of terrestrial isopods (woodlice) has been investigated. Observations have been made on live juveniles of Oniscus asellus and Porcellio scaber in which some digestive processes can be observed directly through the cuticle. The fine structure of the foregut of juveniles and adults of these two species has been studied by light microscopy and scanning and transmission electron microscopy. The passage of coloured dyes and colloidal gold through the digestive system has also been followed.The digestive system of Oniscus asellus and Porcellio scaber is divided into five regions. The foregut (1), and the anterior chamber (2), papillate region (3) and rectum (4) of the hindgut, are ectodermal in origin and lined with cuticle. The hepatopancreas (5), which opens into the foregut, consists of four blind‐ending tubules which are endodermal in origin and not lined with cuticle. A powerful muscular sphincter is present between the papillate region and the rectum. There is no peritrophic membrane in the lumen of either the hepatopancreas or the hindgut.Fragments of food pass via the oesophagus to the proventriculus of the foregut where they are briefly masticated before passing rapidly into the anterior chamber of the hindgut. During this process, the food is mixed with secretions derived from the hepatopancreas. The anterior chamber possesses a pair of dorsal channels formed from a typhlosole and lateral infoldings of the gut wall. When the hindgut is full of food, contraction of muscles surrounding the gut forces liquids and fine food particles back into the foregut via the typhlosole channels which open at the junction of the anterior chamber and papillate region. This material, which contains fluids derived from the hepatopancreas, and products of digestion, is filtered in the foregut and passed into the lumen of the hepatopancreas where further digestion, and absorption of nutrients, takes place. The hepatopancreas may secrete these fluids back on to the food in the anterior chamber and receive products of digestion via the typhlosole channels several times during a digestive cycle.The lumen of the foregut, hindgut and hepatopancreas often contains a dense population of microorganisms which may be involved in digestion. Residual material in the hindgut passes eventually into the rectum where faecal pellets are compacted before they are voided.The ability of terrestrial isopods to recycle and retain fluids within the digestive system, by the development of the typhlosole channels (which are not present in marine isopods), may have been a major contributory factor in their successful transition from water to land.
The ecological significance of resting sites and the seasonal habitat change in polecats (Mustela putorius)
Authors: WEBER DARIUS 
Published: March 2009

The daytime resting sites of 13 radio‐tracked polecats (Mustela putorius) were recorded in a mountainous and a lowland study area in Switzerland. Information on breeding sites was collected from questionnaires distributed throughout the country. At all resting sites, the polecats were completely invisible from more than a metre distant. During summer, when polecats mainly live in forests, individuals used many different hiding‐places (e.g. small self‐dug burrows, woodpiles, heaps of branches and dry leaves, dense vegetation). Such places were used for short periods, and then abandoned. Above ground, the polecats sometimes built nests of dry grass or moss. In winter, the polecats slept mainly inside barns, stables and other buildings. These resting sites were changed less frequently. In rainy weather throughout the year, subterranean places were preferred. Breeding polecats were often found inside houses, and obviously did not avoid human presence.The importance of different types of resting sites for polecats is discussed. In summer, the quality of a resting place is of less importance than its distance from the foraging area, but in winter, warm resting places are essential and buildings are therefore considered an important resource for polecats in Switzerland. The seasonal habitat change can more readily be explained as a consequence of thermoregulatory problems than of food availability, and the distribution of polecats in Switzerland may be affected by the availability of suitable winter resting places. The northern limit of polecat distribution and its historical changes can be explained by the changing availability of human buildings which provide winter resting sites.
Are the New and Old World wapitis (Cervus canadensis) conspecific with red deer (Cervus elaphus)?
Authors: LOWE V. P. W. , GARDINER A. S. 
Published: March 2009

Some taxonomists have classified red deer and wapiti as being conspecific (Ellerman & Morrison‐Scott, 1951; Flerov, 1952); others have split them into two species, Cervus elaphus and Cervus canadensis (Hall & Kelson, 1959; Whitehead, 1972). The decision has been made each time largely on the basis of the size and form of the antlers, the proponents arguing that antler form is a good genetically‐based character, while the opponents view the antlers as being phenotypically very variable, depending largely on the environment for their formal expression.To avoid this controversy, we have used skull measurements, and only female material to reduce the possible effects of bias due to selection by hunters.The enzyme study methods of Gyllensten et al. (1983) and Dratch & Gyllensten (1985) were considered inappropriate as they may reflect only physiological relationships, and rely on living material. Several races of New and Old World wapiti are now either extinct or very rare. Moreover, skull morphology will remain the basis for the classification of most vertebrate species.Sixteen variables, comprising length, breadth and depth measurements, were measured on 298 skulls, representing most of the different races of red deer and wapiti in both the Old World and the New. These sets of variables were analysed by Principal Component Analysis, and the first two components, accounting for 86.4% of the total variance, were plotted as a graph.The first component was clearly a measure of skull size, while the second component gave the greatest weightings to the breadth of the nasals and depth of the nose, in other words, skull shape.All the Old World red deer and wapiti samples formed a continuum of variation in skull size and shape; the only discontinuity being between these races and the North American wapiti, which differed from them mainly in size.The latter could therefore be classified as a subspecies of red deer, Cervus elaphus canadensis. However, because differences in other characters such as behaviour and reproduction are so slight, there appears to be no justification for distinguishing between them at the species level.
Prey detection by some predatory Coleoptera (Carabidae and Staphylinidae)
Authors: WHEATER C. P. 
Published: March 2009

The prey detection methods of 12 species of Carabidae and one species of Staphylinidae were investigated using video and orientation techniques. The species examined were Cicindela campestris, Cychrus caraboides, Carabus problematicus, C. violaceus, Calosoma maderae, Nebria complanata, Scarites abbreviates, Broscus cephaloles, Pterostichus madidus, P. melanarius, P. niger, Abax parallelepipedus and Staphylinus olens.All the species examined were seen to respond to prey upon contact (either by tactile or gustatory reception) during locomotor activity. Tests using orientation chambers showed that some of the species would orientate towards prey in the absence of contact. Some species orientated using vision (C. campestris, C. maderae, S. abbreviates, A. parallelepipedus). This was most frequent when tested with fast‐moving prey. In others, orientation towards prey occurred when olfactory cues were available (P. madidus, P. melanarius, P. niger and A.parallelepipedus). All of the species employing this method of prey detection belonged to the Pterostichini and it appears that the receptors involved are situated on the antennae. Although some species did not orientate towards prey in the absence of contact cues, some of these species were found to respond to slug mucus (C. caraboides, C. problematicus, C. violaceus and S. abbreviates). The receptors for this are probably situated on the terminal ends of the palps. The method of prey detection used is discussed in relation to the ecology of the species.
Resistance to desiccation and distribution patterns in the land snail Sphincterochila
Authors: SHOSHANA GOLDENBERG Z. ARAD , HELLER J. 
Published: March 2009

The land snail Sphincterochila is represented in Israel by five species that replace one another along a climatic gradient that ranges from the Mediterranean areas receiving up to 1000 mm down to arid areas receiving only 70 mm of rain per year.The resistance to three weeks of desiccation was studied in all five species. Total water loss was lowest in the desert‐dwelling species S. zonata and highest in the Mediterranean S. aharonii and the desert‐dwelling S. prophetarum, while the steppe‐dwelling S. cariosa and S. fimbriata were intermediate. Sphincterochila zonata had a significantly thicker epiphragm, the lowest area specific water vapour conductance, the quickest response to desiccation (secretion of epiphragm), and a favourable surface‐to‐volume ratio compared to all other species. The Mediterranean‐type water economy of S. prophetarum, despite its desert distribution, is related to its being an under‐rock‐dweller while S. zonata, which has the best adaptions to desiccating conditions, thrives in exposed areas. It is concluded that the differences in resistance to desiccation among the five species of one genus correspond to the gross distribution patterns and reflect the abiotic regime and the microhabitat of each species.
Total body water and adaptive water turnover rate in four chromosomal species of subterranean mole rats of the Spalax ehrenbergi superspecies in Israel
Authors: YAHAV S. , SIMSON S. , NEVO E. 
Published: March 2009

Total body water (TBW) and water turnover rate (WTR) were measured in 24 subterranean mole rats comprising four populations, each belonging to a different chromosomal species of the Spalax ehrenbergi superspecies in Israel. The four species range in different climates: humid‐cool (2n = 52); semiarid‐cool (2n = 54); humid‐warm (2n = 58) and arid‐warm (2n = 60). TBW, as a percentage of body weight, measured by tritiated water (HTO), was 72.4%±4–7 in 2n = 52, significantly (P< 005) higher than the similar estimates 61.7%± 7.2, and 59.4%± 5–3, for 2n = 60 and 58, respectively. A comparison of HTO space, as a percentage of TBW, closely approximated TBW, ranging from 97% to 108%. WTR was high, 218.1 and 230.9 ml/kg0‐75/day in the mesic populations of 2n = 58 and 52, respectively. By contrast, WTR estimates were significantly lower, (P < 0.001), 150.2 and 148.9 ml/kg0‐75/day in the xeric populations of 2n = 54 and 60, respectively. The biological half‐life time, T1/2, was similar and faster, 32.7 and 27.9 hours in the mesic populations of 2n = 52 and 58, as compared with slower, 47.9 and 40.8 hours in the xeric populations of 2n = 54 and 60, respectively. Urine osmolarity in the most xeric northern Negev steppic population of 2n = 60 (737 ± 45 mmol/kg) was significantly (P < 0.001) higher than in the other species.We conclude that adaptive radiation in the Spalax ehrenbergi superspecies involves speciation in semiarid (2n = 54) and arid (2n = 60) climates by physiological adaptations of kidney water conservation, along with multiple morphological, physiological and behavioural syndromes of climatic adaptations to increasing aridity (Nevo, 1986).
The functional morphology of Propeamussium lucidum (Bivalvia: Pectinacea), a deep‐sea predatory scallop
Authors: MORTON B. , THURSTON M. H. 
Published: March 2009

The abyssal propeamussiid Propeamussium is well known from studies of shell structure and is believed to be representative of a relict lineage, sister to the group which gave rise to all shallow‐water pectinaceans.From analyses of stomach contents, species of Propeamussium have been reported to be predators. This study confirms this and shows that small meiobenthos or epibenthic planktonic larvae and crustaceans constitute the diet. Prey is thought to be caught by an inrush of water to the mantle cavity and pushed into the mouth with the foot. The stomach is small, secondarily simplified and adapted for the digestion of small creatures. It is convergent with the stomachs of similarly predatory, abyssal anomalodesmatans. Palps are vestigial. The ctenidia are of a new type (B(4)), perhaps derivable from the dimyid ctenidium by the loss of the ascending lamellae of all four demibranchs and the ventral fusion of inner and outer descending lamellae on each side of the body to create a gill where the apices of the filaments are internal. Filter feeding is thus impossible, the ctenidia now wholly subserving a respiratory function.Aspects of shell structure, adductor muscle arrangement and form of the pallial margin suggest that P. lucidum is a proficient swimmer. It is concluded, however, that prey is not caught during swimming, and that the two activities are mutually incompatible. Probably swimming is used only for escape.Ctenidial structure forges links with the Plicatulacea (Dimyidae, Plicatulidae), shell structure with the Pectinacea (Pectinidae, Spondylidae) and it is concluded that the Propeamussiidae is indeed a relict group with links back to more primitive plicatulaceans and with the modern shallow‐water Pectinacea, but evolving, in the isolation of the abyss, remarkable adaptations for a predatory mode of life. The Propeamussiidae also demonstrate striking convergence with the abyssal predatory Anomalodesmata.
Structure and histochemistry of the dermis of a chequered water snake, Natrix piscator
Authors: Singh Jai Prakash Narain , Mittal Ajay Kumar 
Published: March 2009

The histology and the protein, carbohydrate, lipid and enzyme histochemistry of the dermis of the chequered water snake, Natrix piscator, have been examined throughout the sloughing cycle.The structural organization and staining properties of the dermis do not show any changes in different stages of the cycle.The dermis is divided into the stratum laxum and the stratum compactum. Acid mucopolysaccharide deposits in the stratum laxum, which possibly bind water, may be involved in prevention of desiccation.The numerous elastin fibres in the hinge regions are related to the greater elasticity of the skin in these sites.
The social structure and reproductive biology of the common mole‐rat, Cryptomys h. hottentotus and remarks on the trends in reproduction and sociality in the family Bathyergidae
Authors: Bennett N. C. 
Published: March 2009

Cryptomys h. hottentotus occurs in mesic and semi‐arid regions of South Africa. It lives in colonies ofup to 14 individuals, in which reproduction is limited to one ofthe largest males and the largest female in the colony.Reproduction and details of colony size and the number of breeding animals in a colony are described for one complete and two incomplete field‐captured colonies. One incomplete colony was kept in captivity for more than 3 years, whereas the complete colony was autopsied.The social hierarchy of the common mole‐rat is almost linear and has a value of 0.7 1 calculated from Landau's linearity index. Subordinate mole‐rats weighed less than dominant mole‐rats. The reproductive mole‐rats are the dominant animals within the colony. The non‐reproductive females rank lowest in the hierarchy.Mating was not confined to a particular season, but occurred more frequently during the summer months. The alpha male initiated pre‐copulatory behaviour. The gestation length is 55 to 66 days (n = 2). Two litters each of three pups were born to the colony during captivity. The pups were relatively altricial. They wandered out of the nest 5 days after birth, began to eat solids when 10 days old, and were fully weaned at 4 weeks. When 2 weeks old the pups began to spar with each other and with some of the adult colony members, but levels of aggression were never high. The pups did not disperse but were incorporated into the colony, this suggesting that C. h. hottentotus colonies are largely composed of related individuals.