bluuebunny/crossref_metadata_2025_split huggingface dataset:
The biology and functional morphology of Claudiconcha japonica (BivaMa: Veneracea)
Authors: Morton Brian 
Published: August 2009

Claudiconcha japonica Dunker 1882 is a member of the Petricolidae in which family there is a clear trend towards a tunnelling mode of life culminating in the evolution of species such as Petricola pholadiformis–a borer of soft rocks and shales–with appropriate anatomical and morphological adaptations. Such convergent adaptations recall those seen in another unrelated group of rock‐borers–the Pholadidae.The tunnelling habit in modern petricolids undoubtedly arose from a nestling mode of life which is commonly encountered in other members of the Veneracea. Some, possibly more primitive, petricolids only have the ability to enlarge the crevice they inhabit. C. japonica is different, however, in that for the first part of its life it is a motile (though usually found byssally attached), equivaive bivalve. With site selection, however, the margin of the right valve undergoes considerable enlargement to curl around and partially enclose the unmodified left valve. This development, associated with the selection of a crevice for permanent habitation, has no effect upon the disposition of the organs of the mantle and body cavities as in other inequivalve bivalves and they remain typically bilaterally equal.It is impossible for C. japonica to tunnel since the secondary development of the right valve fills the chosen site and in so doing comparatively immobilizes the left valve and closes the pedal gape. Thus C. japonica and its close relatives must be considered to be on a separate line of evolution from other petricolids and it is doubtful that the present sub‐generic status of Claudiconcha is sufficient to highlight this difference. It seems more appropriate to genericize this name thereby amplifying this trend.In other morphological respects, which are described, C. japonica is clearly a member of the Petricolidae and functional aspects of these adaptations suit the animal to a life in relatively clear waters but where nevertheless the niche tends to accumulate detritus which must be kept out of or removed from the mantle cavity.The secondary enlargement of the right valve, associated with the selection of a suitable site for permanent habitation also appears to be associated with the onset of sexual maturity –a feature again reminiscent of the tunnelling Pholadidae.
Age determination in the Red fox (Vulpes vulpes)–an evaluation of technique efficiency as applied to a sample of suburban foxes
Authors: Harris Stephen 
Published: August 2009

A review of age determination techniques that have been applied to the family Canidae is presented. It is shown that the pattern of growth and development of the various species is very similar, the rate of development being greater in the smaller, shorter‐lived species, and vice versa.The occurrence of annuli in the hard tissues of London foxes is demonstrated; these annuli can be used reliably for age determination, despite suggestions that temperate zone animals from weakly continental climates have indistinct annuli. The objective ages determined by cementum annuli are then used to investigate the value of less time‐consuming age determination techniques, particularly in the separation of the young‐of‐the‐year from adults. The results obtained from different studies vary, and these differences are discussed. It is suggested that the speed of development varies slightly in different Red fox populations, and so caution must be exercised before data from one population areapplied to another population.
The occurrence and life history of Asymphylodora kubanicum (Platyhelminthes: Digenea: Monorchidae) in the Worcester‐Birmingham canal, with special reference to the feeding habits of the definitive host, Rutilus rutilus
Authors: Evans N. A. 
Published: August 2009

Two hundred roach and over 400 molluscs were examined over a one year period to investigate the occurrence and life history of Asymphylodora kubanicum in the Worcester‐Birmingham canal. Larval stages, infective to the fish definitive host, were present in molluscs throughout the year but did not show a seasonal fluctuation in numbers. Parasites in the intestine of the roach showed a marked annual cycle of occurrence and maturation: low winter infection levels preceded a dramatic increase in infection during the spring and summer. Maturation of the parasite population was rapid during the spring and summer and in late summer and early autumn the parasites laid their eggs and subsequently died. The death of parasites after egg‐laying resulted in the low winter infection level during which time little recruitment occurred.Roach became infected mainly in their third year when molluscs become a dominant component of their diet. Thereafter the older fishes (<2+) are all equally susceptible to infection, but the larger (older) fishes become more heavily infected because of the greater consumption of molluscs per fish. The sex of the fish made no difference to infection with the parasite.
A comparison of the origin and temporal arrangement of pulsed sounds in the songs of the Grasshopper and Sedge warblers, Locustella naevia and Acrocephalus schoenobaenus
Authors: Brackenbury JohnH. 
Published: August 2009

The songs of the two British warblers Locustella naevia and Acrocephalus schoenobaenus were examined by means of oscillographic recordings. Both songs are composed of pulsed elements arranged in rhythmical successions. The song of L. naevia is simple and stereotyped consisting of a succession of paired pulses with a repetition frequency of 26 Hz. The song of A. schoenobaenus contains many different phrases each consisting of a succession of identical chirps. Chirps consist of successions of pulses, the number and repetition rate of which vary from phrase to phrase.The songs are discussed in relation to the physiology of sound production and to the way in which information is encoded into sound signals. It is proposed that pulses are produced by the syringeal muscles, whilst the rhythm, tempo and duration of chirps and phrases are controlled by the respiratory muscles. A distinction is drawn between the action of the extrinsic syringeal muscles, which may produce low frequency pulses, and the intrinsic syringeal muscles, which may produce high frequency pulses.The codal format in both songs is shown to be highly redundant, being based on the repetition of identical units of information. This device reduces the possibility of distortion of meaning by interference from environmental noise but limits the information carrying capacity of the code. The method of pulse coding is shown to be particularly well suited to the avian auditory system which is adapted to receiving and processing rapid transient signals. This ability is in part attributable to the fine discrimination of time and amplitude changes in the cochlea.
Metabolite‐mediated density‐dependent sex determination in a free‐living nematode, Diplenteron potohikus
Authors: Clark W. C. 
Published: August 2009

The nematode Diplenteron potohikus (Yeates) (Rabditida: Diplogasteridae) shows facultative parthenogenesis: males occur, but rarely exceed 20% of the population. When reared singly in monoxenic culture with Bacillus cereus the eggs always gave rise to females. When reared at 2–50 eggs per 5 cm Petri dish up to 16% developed as males. At higher densities the proportion of males declined. Male‐determining properties could be transferred from old culture media to new media in an aqueous cell‐free leachate of the old media. The effects of this leachate could be mimicked by several indole compounds though indoles could not be detected in the leachate by thin‐layer chromatography. The addition of either indoles or leachate extended development time at 20°C by about 25%. Further effects attributed to the accumulation of the metabolite in old cultures were the inhibition of hatching of embryonated eggs, and the inhibition of the development of the posterior branch of the female reproductive system and its ovary. Both of these phenomena were reversed by transfer of the eggs, or the mature females to fresh media.Such a pheromone‐like substance may be of value in preventing the production of males when populations are small and the probability of finding a mate is low. Thus the production of males at times when their value is low is avoided.
Morphometries of the respiratory organs of the Indian green snake‐headed fish, Channa punctata
Authors: Hakim A. , Munshi J. S. Datta , Hughes G. M. 
Published: August 2009

Measurements of the dimensions of the different gills and the suprabranchial chambers have been made and the data analysed with respect to body weight using logarithmic transformations (Y = aWb). The slope (b) for area of the total gill surface is 0–592 and for the supra‐branchial chamber 0–696, and their combined respiratory surface: 0–623. The slope values for the surface areas of the 1st, 2nd, 3rd and the 4th gill arches were 0–595,0–578,0–614 and 0–572 respectively.The slope for secondary lamellae/mm is –0138 and that for the bilateral surface area of an average‐sized lamella 0–304.These results indicate differences in growth patterns for the dimensions of the different gills. The growth‐related decrease in the number of secondary lamellae/mm and size of an average secondary lamella together with evidence from “drowning” experiments and diffusing capacity calculation, suggest that this fish is better adapted for aquatic respiration than Anabas or Saccobranchus. The slopes for the total respiratory surface area and gill area seem to be comparatively low in this species.
The distribution of organic cores, cones, cone junctions and pores in the egg shells of wild birds
Authors: Tyler C. , Fowler Sue 
Published: August 2009

Egg shells from 14 widely different species of wild birds were examined, using collodion casts of the inside surface of the shell. Organic cores, cones, cone junctions and pores were counted and in each case measurements of nearest neighbour distances were taken. Shell thickness was also measured.It was found that, using mean values for each egg shell, there were highly significant, and in some cases almost perfect linear relationships between core numbers, cone numbers, cone junction numbers and pore numbers on the one hand and their respective nearest neighbour distances expressed as the reciprocal of the mean of the squares of these distances on the other. The results also showed that the distribution of all four structures was not random, but had a degree of uniformity increasing up the series pores < cone junctions < cores < cones.The following relationships were also highly significant: core and cone numbers, core and cone junction numbers, and cone and cone junction numbers. The relationship of pore numbers to any of the other three structures was of no great significance.Shell thickness was related curvilinearly to core numbers and to cone numbers and linearly to nearest neighbour values for cones. It was also related to pore numbers.It is suggested that, apart from pores the other three structures and their distribution all depend upon the number of cores which are the original centres of crystallization from which the shell grows. To a lesser extent shell thickness also depends upon these structures. Tentative suggestions are also made concerning the origin of the pores.
Ecological studies on Indonesian lakes. The montane lakes of Bali
Authors: Green J. , Corbet Sarah A. , Watts E. , Lan Oey Biauw 
Published: August 2009

Of the two Balinese lakes revisited in 1974, 45 years after an earlier survey, the unproductive Danau Bratan, with a very low conductivity, showed changes in water chemistry and plankton composition that may reflect slight cultural eutrophication. Danau Batur, a larger lake with a very high conductivity, showed little change since 1929.Danau Bratan is also compared with the two previously uninvestigated lakes that lie in the same caldera: Danau Buyan and Danau Tamblingan. Differences between the three lakes in this series in the stability of stratification, the composition of the plankton, the vegetation, the marginal fauna, the diets of guppies and the fisheries are discussed in relation to differences in exposure to wind and in the effects of human settlement on the shores.
Optimum walking techniques for idealized animals
Authors: Alexander R. McN. , Jayes A. S. 
Published: August 2009

The vertical component of the force exerted by a foot on the ground, in the course of a step, may rise to a single maximum and decline again (as in human running) or may show two distinct maxima (as in human walking). A foot may remain on the ground for a large or small fraction of the duration of a stride. Mathematical models are used to investigate the effects of these differences of technique on the energy cost of locomotion. The optimum technique for a biped at a given speed is different from the optimum for a hypothetical many‐legged animal. The optima for quadrupedal walking are likely to lie between these extremes.The walking techniques adopted by men at different speeds are close to the optima indicated by the bipedal model. The two maxima of the force exerted by a foot are higher, and have a lower minimum between them, at higher speeds of walking. The techniques adopted by a sheep are close to the optima indicated by the many‐legged model but dogs use techniques rather closer to the optima for bipeds.The limitations of the models are discussed.
On leucophores and the chromatic unit of Octopus vulgaris
Authors: Froesch D. , Messenger J. B. 
Published: August 2009

The leucophores of Octopus vulgaris are much branched cells bearing, all over the surface, small clubs that contain electron‐dense material of an unknown nature. Some tens of leucophores are organized to form a “sponge” in the centre of the chromatic unit, which can be elevated above the peripheral region. This central region reflects light over a broad band and may be important in camouflage.The chromatic unit also contains iridophores and chromatophores. The latter may be yellow, orange, red or black, and the different types are interspersed among one another in a regular manner. The chromatophores are disposed in a precise way with respect to the leucophores, the black ones lying above holes in the sponge. The possible significance of this arrangement for camouflage is discussed.
A functional and phylogenetic interpretation of the skull of the Erycinae (Reptilia, Serpentes)
Authors: Rieppel Olivier 
Published: August 2009

Based on skull structure, the genus Gongylophis Wagler is again placed in synonomy with the genus Eryx Daudin. Lichanura is considered to be structurally close to the early erycine stock from which Charina evolved as an early, separate off‐shoot.Skull characters which adapt erycines to burrowing habits show clinal variation: they involve shortening of the skull and streamlining of its contours through snout depression, the development of a spatulate transverse process of the pre‐maxilla reinforced by the nasals and a specialization of the naso‐frontal joint which supports the snout. The jaws retain their mobility. Burrowing habits are a specialized feature of the Erycinae.
Biological observations on the crater lakes of Jebel Marra, Sudan
Authors: Green J. , Moghraby A. I. el , Ali O. M. M. 
Published: August 2009

Two lakes lie in a caldera at the top of Jebel Marra. One is shallow and highly saline, with a dense bloom of planktonic blue‐green algae and a zooplankton consisting entirely of rotifers. The other is over 100 metres deep, is less saline, with a sparse phytoplankton of diatoms, and the dominant zooplankter is Eucyclops gibsoni. The marginal fauna of the deep lake includes a number of widespread insects, but is unusual in that it includes an aquatic glowworm (Family Lampyridae).In the shallow lake there is a superabundance of oxygen in the upper two metres, but no oxygen below six metres, except when strong winds mix the lake so that there is then about 40% saturation throughout the water column. In the deep lake it was found that after strong winds there was only about 12% saturation in the top 30 metres of water. The restricted fauna of these lakes appears to be a result of the combined effects of isolation, salinity and a variable oxygen regime.
Activity patterns of Pipistrelle bats (Pipistrellus pipistrellus) in north‐east Scotland
Authors: Swift Susan M. 
Published: August 2009

Pipistrellus pipistrellus emerge from their nursery roosts in north‐east Scotland about 35 minutes after sunset, at light intensities of between 15 and 35 lux. Cloud cover, windspeed, ambient temperature, rain, light mist and moonlight have no apparent effect on the time or pattern of emergence. Throughout pregnancy and lactation, emergence lasts for about an hour. After weaning, when the adult females have left the roost, their young take about 40 minutes to emerge. The average rate of initial emergence is proportional to colony size, and the maximum rate of emergence occurs half way through the exodus.During pregnancy in May and June most bats leave the roost once each night soon after dusk and return between midnight and dawn. After parturition in late June the activity pattern becomes bimodal and the numbers of bats outside the roost show peaks after dusk and immediately before dawn. There is intermittent activity in the vicinity of the roost all night and bats make two or three flights each night. After weaning in August the activity pattern gradually ceases to be bimodal, and the number of flights per bat falls to between one and two. The average time spent outside the roost varies between 2–5 and 5 hours during the summer. The recorded activity patterns of night‐flying insects are all bimodal, with peaks after dusk and before dawn, corresponding with the maximum number of bats outside the roost during lactation.
Population ecology of Tatera leucogaster (Rodentia) in southern Zambia
Authors: Chidumayo E. N. 
Published: August 2009

A population of bush gerbils, Tatera leucogaster Peters, near Livingstone in southern Zambia was studied from January 1974 to December 1976. The population went through a peak, decline and was in a low phase at the end of the study.Prior to and during the peak phase in 1974 the breeding season lasted for nine months but during the year of decline breeding occurred for only four months. There was also a decline in the reproductive effort of subadults and adults during the year of decreasing numbers. The sex ratio was significantly biased for females prior to realization of peak numbers.Post‐weaning mortality had the strongest impact on changes in numbers. Post‐weaning and later survival was very good (over 60 %) during the population peak but was poor (under 40%) during the decline phase.
Swimming in Amusium pleuronectes (Bivahia: Pectinidae)*
Authors: Morton Brian 
Published: August 2009

Aspects of functional design in the Pectinidae have led scientists to speculate that scallops of the Amusium group (Hertlein, 1969) are among the best swimmers. This study of Amusium pleuronectes confirms this view, with average swimming speeds ranging from 37–45 cm/second. A speed of 73 cm/second was recorded from one scallop. Swimming times varied, on average, between 8–10 seconds; one scallop, however, swam for 18 seconds, covering a distance of 10 metres.This study has also investigated pertinent aspects of the functional design of A. pleuronectes, including the adaptations to the shell, mantle and musculature that increase swimming efficiency: These include: (1) A thin, very smooth, biconvex, rounded shell; (2) Internal strengthening ribs; (3) A small valve convexity; (4) A more central point of maximum valve convexity; (5) Upturned antero‐ and postero‐lateral upper valve margins; (6) Emarginated anterior and posterior shell margins; (7) A highly elastic ligament; (8) A single large, centrally located, adductor muscle; (9) Small perpendicularly oriented “slow” and large obliquely oriented “quick” adductor muscle components; (10) Expulsion of water both antero‐and postero‐dorsally; (11) Highly muscular middle and inner mantle folds acting as a (mechanical) “valve” to direct and regulate water flow.It has occasionally been reported in the literature that small scallops swim “better” than large specimens of the same species; this has been investigated for A. pleuronectes and the general conclusion is that large scallops can swim just as well as small specimens (indeed distances covered are greater in animals of the former category), but that the threshold stimulus necessary for swimming to occur is raised. This is true also of the escape reaction; small scallops are much more likely to perform an escape response of between one to three adductions than large specimens which seem to rely more on sustained adduciion for protection. Earlier authors have advocated ontogenetic allometric growth changes in the position and obliquity of the “quick” component of the adductor muscle to explain how larger scallops overcome the increasingly negative forces of gravity and drag. No evidence of such allometric changes have been recorded for A. pleuronectes and the present author believes that the increasingly negative forces of drag and gravity are easily overcome by scallops of any size. Increasing weight with age and physiological ageing of the adductor muscle is probably sufficient to account for differences in swimming ability between small and large specimens of A. pleuronectes.It is finally concluded that swimming in A. pleuronectes is not a response to predation. Circumstantial evidence is presented which, when considered with the efficiency of swimming and aspects of functional design in this species, suggests that swimming is concerned with active and seasonal migration, possibly linked to reproduction.
The trigeminal jaw adductors of primitive snakes and their homologies with the lacertilian jaw adductors
Authors: Rieppel Olivier 
Published: August 2009

The trigeminal jaw adductor musculature of anilioid snakes is analysed. The group is characterised by primitive characters, viz. the presence of an extensive bodenaponeurosis and of a quadrate aponeurosis. A temporal tendon gives rise to superficial (lb) fibres which are not observed in other snakes: this may be a primitive or a derived feature.Jaw adductor muscles in snakes are usually subdivided following their relative position in an antero–posterior direction. Lacertilian jaw adductors are subdivided in a transverse plane. A detailed comparison of the anilioid and primitive lacertilian jaw adductors establishes correspondences (homologies) of parts in the transverse plane in both groups. These homologies are corroborated by innervational patterns.Platynotan lizards are widely accepted as potential snake ancestors. A comparison of homologue jaw adductors shows different evolutionary trends to characterise platynotan lizards and snakes. Theoretically, these findings do not rule out primitive platynotan lizards as snake ancestors. On the basis of the structure of jaw adductors, snakes are to be derived from a primitive lacertilian pattern, be it platynotan or not.
Structure of the plantar sweat glands of the Bank vole Clethrionomys glareolus
Authors: Griffiths Joanna , Kendall Marion D. 
Published: August 2009

The plantar pads of the hind feet of 15 male and female, young and old Clethrionomys glareolus (Rodentia–family Muridae) were examined for the presence of tubular glands. Groups of eight or nine coiled glands were found in all of the 11 plantar pads. The secretory portion of the gland lies deep in the fatty hypodermis and communicates with the plantar surface by a coiled duct whose lining cells merge with those of the stratum basale of the undersurface of the foot. Groups of shallow depressions mark the site of the duct openings. They are not associated with any hairs.Although light microscopy shows only one cell type, electron microscopy reveals two morphologically different cell types. Neither conform directly to the light and dark secretory cells of the human sweat glands although similarities exist. Myoepithelial cells surround the secretory cells, but do not appear to be present around the duct cells.