摘要:

Bufo calamitais on the edge of its range in Britain, and exists only in three widely separated geographical regions of the country. The largest populations with the highest densities of animals are found on the Irish Sea coast. Data on the chronology of breeding activity show that the reproductive season for these thriving populations starts and finishes earlier than that for toads in eastern England, but that first records of metamorphosis occur at similar times throughout the country. The possible significance of these observations to the variable success of the species in the different geographical regions is discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05608.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Three cell types are described from the coelomic cavity of the pedicle of the brachiopodLingula anatina. Erythrocytes are abundant in the blood vessels of the mantle and also occur, in reduced numbers, in the pedicle. Phagocytic amoebocytes, characterized by a variable number of electrondense, homogeneous granules are common in the coelomic fluid of the pedicle. The enigmatic spindle bodies described by earlier authors constitute the most common cell type encountered in the pedicle coelom of aquarium‐maintained specimens. The origin of spindle bodies from muscle cells is suggeste

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05609.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The lungs of two adult species of batEpomophorus wahlbergiandMiniopterus minorfixed with 2.3% glutaraldehyde were processed for SEM (scanning electron microscope) and TEM (transmission electron microscope) examination by the standard procedures. The bat lung comprised a blood and air conducting zone (consisting of bronchi, bronchioles and large blood vessels), the intermediate zone (made up of alveolar ducts), and the respiratory zone, which consisted of alveoli and blood capillaries. The interalveolar septa comprised basically granular pneumocytes (type II cells), squamous pneumocytes (type I cells), endothelial cells, and, in the interstitium, collagen and elastic fibres with occasional fibrocytes. Blood capillaries were interposed in the interalveolar septa, thus bulging into adjacent alveoli. It was noted that grossly, architecturally and structurally, the bat lung was similar to that of a terrestrial mammal. However, in previous morphometric and physiological studies it has been found that bats have a large lung, a thin pulmonary blood‐gas barrier, a large pulmonary capillary blood volume, and high haematocrit and haemoglobin concentration. The bat lung, while retaining the basic mammalian pulmonary design, is well adapted to provide the large amount of oxygen demanded by flight. The avian pulmonary design (the lung‐air sac system) is thus not a prerequisite to fli

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05610.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Total surface area of the ion‐permeable lamellar gills ofCorophium volutatorandCorophium curvispinumis 0·81 mm2mg‐1and 0·78 mm2mg‐1(wet weight), respectively. In both species, haemolymph flow (as visualized by haemocyte movements) is rapid through the peripheral canal and central luminal lacunae of each gill, general flow being from posterior to anterior margin of the gill. There appears to be countercurrent flow of haemolymph and ventilatory current water over the gill integument, which may facilitate dissolved‐gas exchange.Rate of haemolymph flow (perfusion) through the gills of the euryhalineC. volutatoris markedly reduced immediately following transfer to a considerably hyperosmotic salinity (e.g.15% S.W. to 85% S.W. transfer). No reduction in the rate of gill perfusion occurs following transfer ofC. volutatorto hypoosmotic salinity. The freshwaterC. curvispinumdoes not tolerate hyperosmotic salinity transfers, but does exhibit a similar immediate gill perfusion restriction. The onset of gill perfusion restriction is dependent on a change in the magnitude of the ionic ([NaCl]), not the osmotic, gradient across the integument. InC. volutatoronly, normal rate of gill perfusion is eventually restored (within 24 hours of transfer), but can be immediately restored if the animal is transferred back to the acclimation salinity.InC. volutator, branchial perfusion pattern is postulated to be regulated in relation to environmental salinity by a mechanism operating under neural control. The possible significance of gill perfusion restriction toC. volutatoras a short‐term adaptive osmoregulatory response is considered. Perfusion restriction in the gills ofC. curvispinumis considered to be a relic of a recent estuari

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05611.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Using X‐ray diffractometry, the development of preferred orientation was studied in one species from each of the extant ratite families, from two moas and two tinamous and, as a preliminary comparison, from representative species from 16 of the other carinate orders. A preferred orientation begins to develop immediately after the start of shell deposition, and in all shells studied was one in which the (001) planes tend to lie parallel to the shell surface. The degree of (001) texture that develops in the ratite and tinamou shells is greater than that developed in the other carinate orders. Development in the ostrich, kiwi and tinamou is uninterrupted so that there is a very high degree of (001) preferred orientation at the exteriors of the shells. In the Emu, cassowary, rhea and the two moa species, a very high degree of (001) texture reverses gradually within the central layer of the shell, and in some species this is accompanied by the development of a very weak (104) preferred orientation. The weak (001) textures observed in the shells of the 20 species from the carinate orders other than the Tinamiformes develop slowly and without interruption through the shell; in four species a weak (104) texture develops simultaneously to that of the (001), forming a double texture similar to that already reported in the majority of shells of the domestic fow

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05612.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Cineradiographic analysis of the limb movements ofOrnithorhynchusreveals that the proximal limb bones undergo horizontal retraction, long‐axis rotation and distal elevation (humerus) or depression (femur) during the propulsive phase of walking. Cinematographic records show that the locomotor movements ofOrnithorhynchusdiffer in several respects from those ofTachyglossusandZaglossuswhich are essentially similar. Comparison of the propulsive phase limb movements ofOrnithorhynchuswith those previously established radiographically forTachyglossusreveals that the humerus is on average less laterally but more dorsally directed, and that the femur is on average more dorsally and slightly more laterally directed inOrnithorhynchus. Comparison of the limb orientations of monotremes with those empirically determined in therian mammals and lepidosaurian reptiles indicates that monotremes are most similar to therians. Consideration of several evidently derived features of the appendicular skeleton of monotremes leads to the conclusion that the limb orientations used by early mammals were probably similar to those used by locomotively generalized living therians, and that monotremes show modifications of thi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05613.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The hearts of 29 species of macrourid teleosts were examined in this study. For the one species for which a length range was available (Coryphaenoides (C.) rupestris), the heart weight as a percentage of body weight was 0·059. This is similar to values for relatively inactive fish. The atrial myocardium was reduced and had only a sparse trabecular network. In some species it was surrounded by a highly developed epicardium, but in others there was interstitial connective tissue in the myocardium that may serve to strengthen this chamber. The ventricle was entirely spongy, and all species lacked an outer compact layer of myocardium and associated coronary vasculature. All the ventricles were sac‐like in form. The bulbus arteriosus was highly complex, and in its proximal portion there was an endothelially‐lined, inner tube surrounded by a spongy network of blood‐filled spaces, outside which was an outer compact layer of smooth muscle and elastica. These features of the bulbus may prevent backflow of blood after ventricular systole. The endothelial cells lining the bulbus were usually PAS‐positive and in some species contained acid mucopolysac

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05614.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Jackass penguin chicks from the age of about 10 days were hand reared on different diets: mulletLiza richardsoni, anchovyEngraulis capensisand squidLoligo reynaudi, until they fledged. The weight of food fed and the daily weight increment of the chicks was measured. Excreta were collected every 5–6 days and analysed to establish metabolized energy and metabolic efficiency. Culmen measurements were taken regularly and plotted against age. The age, weight and sum of food fed up to fledging was compared between diets as well as with field data. Compensatory growth was exhibited when stunted chicks on a relatively poor diet had their diet changed to a relatively better die

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05615.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effect of temperature on thermoregulation, metabolism, evaporative water loss and thermal conductance was studied inGerbillus pusillus. Its resting body temperature (TB) was 34·6°C, approximately 5°C higher than the mean ambient temperature (TA) encountered in its burrow. As TA increased above 34°C, its ability to lose heat to the environment decreased. It overcame this problem by tolerating increases in TB to a non‐lethal maximum of 41°C, whilst also eliminating increasing quantities of obligate heat by pulmocutaneous evaporation and conduction.Metabolic rate was 41% lower than that predicted from Kleiber's (1975) allometric equation. This confers a considerable saving in energy in an environment where food is often scarce, whilst simultaneously reducing heat production and the degree of gaseous exchange in the already oxygen‐poor and carbon dioxide‐rich environment encountered in the plugged burrows of its natural milieu.Gerbillus pusillus, therefore, does not maintain strict homeothermy and utilizes a labile TB and reduced metabolic rate as an adaptive mechanism for survival in the arid zones of tropi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05616.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A model is developed which demonstrates the pattern of the relationship between growth rate. body weight, proportion of adult weight attained, and time taken to mature in animals. The relationships of growth rate and time taken to mature, to body weight in primates are examined in relation to this model. Within each of the taxonomic groups: prosimians, New World monkeys, Old World monkeys and great apes, growth rate quite closely parallels the three‐quarter power of weight. After accounting for size, growth rate clearly decreases through this taxonomic list. Man has the slowest growth rate of all primates in relation to his size. The model predicts that, after accounting for differences in size, the daily energy intake during growth may, like growth rate, decrease considerably through the taxonomic groups from prosimians to man. The results form a basis from which to account for the differences due to size and taxonomic position when using monkeys as models for human physiology or disease during growt

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb05617.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY