bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive endocrinology of free‐living nestling and juvenile starlings, Sturnus vulgaris; an altricial species
Authors: Williams T. D. , Dawson A. , Nlcholls T. J. , Goldsmith A. R. 
Published: March 2009

Plasma concentrations of luteinizing hormone (LH), prolactin and testosterone, and pituitary content of LH and prolactin, were measured in free‐living starlings, Sturnus vulgaris, from hatching until 12 weeks of age.Plasma LH concentrations were elevated in both sexes until four days after hatching, then they decreased. Throughout the period, plasma LH levels were low compared to those in breeding adults but were comparable to levels in post‐breeding photorefractory adults. Pituitary LH content increased until 12 days after hatching, but this increase was due to physical growth during this period. Plasma prolactin concentration and pituitary prolactin content increased dramatically during the nestling period. The increase in pituitary prolactin content was in excess of that accounted for by increasing size. Plasma prolactin remained high during the immediate post‐fledging period, but had started to decrease by 12 weeks after hatching. Plasma testosterone concentrations were lower than those in breeding adults, but generally higher than in post‐breeding photorefractory adults. The gonads of both sexes remained regressed.These results suggest that the reproductive system of nestling and juvenile starlings is in a similar state to that of post‐breeding photorefractory adult starlings. The comparatively high levels of testosterone may reflect involvement in sexual differentiation.
Asynchronous male and female life cycles in the sexually dimorphic, harem‐forming isopod Paragnathia formica (Crustacea: Isopoda)
Authors: Upton N. P. D. 
Published: March 2009

The complex life history of the sexually dimorphic, harem‐forming isopod Paragnathia formica Hesse is described, combining published information with new observations. The results of a two‐and‐a‐half year field study, carried out within the animal's saltmarsh habitat, are presented, revealing significant differences in the life cycles of males and females. Settlement to the breeding habitat of final stage male and female larvae, derived from the same annual generation, was recorded at very different times of the year. The total lifespan of males was shown to be twice that of females.The larvae, temporary ectoparasites of estuarine fish, and the non‐feeding, burrow‐living adults are described and categorized into several developmental phases, whose numbers were recorded during the course of the study.The annual production of larvae during a limited period in the autumn, and the subsequent settlement of final stage larval females and males the following year, were monitored. Larval females entered the burrows of adult males in the spring to breed, and died after releasing viviparous broods in the autumn. Larval males settled later in the summer, reaching adulthood in the autumn and overwintering before breeding some 18 months after their birth and dying at the end of the breeding season. Adult males thus bred with females from the next generation. The differences in male and female life cycles led to great seasonal variations in adult sex ratios, a huge winter bias towards males contrasting with a brief excess of females in the summer.
A proposal for the functional and phylogenetic significance of differences in the dentition of lampreys (Agnatha: Petromyzontiformes)
Authors: Potter I. C. , Hilliard R. W. 
Published: March 2009

The shape and arrangement of the teeth and multicuspid laminae of the oral disc and tongue‐like piston are described for parasitic lampreys representing the six holarctic genera (Petromyzonli‐dae) and each of the monogeneric Southern Hemisphere families (Mordaciidae and Geotriidae). Particular attention is paid to describing the divergent dentitional characters, the location of attack and the size of the oral disc and buccal glands of the blood‐feeding Petromyzon marinus and the flesh‐feeding Lampetra (Lampetra) fluviatilis and Lampetra (Lampelra) ayresii. The conclusions drawn from these comparisons are used to make suggestions regarding the feeding biology of other parasitic species of lamprey for which less comprehensive data are available.Compared with P. marinus, the flesh‐feeding L.fiuviatilis and L. fluviatils have fewer and smaller oral disc teeth between the circumoral and marginal teeth, a much wider and deeper supraoral. a far larger central cusp on the transverse lingual lamina (which in turn is convex rather than V‐shaped) and a smaller oral disc and buccal glands. It is proposed that in the two Lampetra species, the central cusp on the transverse lingual lamina and the interaction of this lamina with the supraoral are adaptations for gouging and cutting out pieces of host tissue. By contrast, the serrated edges of the lingual laminae in P. marinus are used to create a small but deep wound through which a stream of blood is then drawn. This mode of feeding is facilitated by the ability of P. marinus to remain attached for long periods at a single location on the host and to secrete a flow of anticoagulant ‘saliva’ from its relatively large buccal glands.Since the characteristics of the feeding structures in the parasitic members of the genera lchthyomyzon and Mordacia resemble more closely those of P. marinus than L. fluviutilis and L. ayresii, they would appear to be adapted primarily for the extraction of blood. On the other hand, the reverse is true of Lampetra (Lethenleron) japoniea and Geotria auslralis, indicating that these species ingest predominantly muscle tissue. Species such as Lampetra (Entosphenus) tridentata have an intermediate type of dentition and are apparently more versatile in their feeding habits.It is concluded that: (i) blood‐feeding preceded flesh‐feeding in ‘modern’ lampreys; (ii) endemic freshwater parasitic species typically ingest blood; (iii) the ability to feed on flesh developed in populations which had access to estuarine and marine hosts; and (iv) pre‐Tertiary forms resembling contemporary lehthyomyzon unicuspsis could have given rise independently to both of the divergent and specialized genera of Southern Hemisphere lampreys (Mordacia and Geolria).
The pallial organ of Atrina pectinata (Bivalvia: Pinnidae): its structure and function
Authors: LIANG X. Y. , MORTON B. 
Published: March 2009

Hitherto, the unique pallial organ of the Pinnidae has been considered to fulfil a cleansing role, removing sediment and shell fragments from the mantle cavity. This study of the pallial organ of Atrina pectinata describes structure in greater detail than before but was unable to demonstrate a cleansing function. Rather, the organ is thigmotropic and massively secretory. Study of the pallial organ head demonstrates it to have a pH of between 2 and 4 and that tall, apparently empty cells in the head epithelium contain sulphuric acid which can be precipitated as barium sulphate crystals following irrigation with barium chloride.Acid‐secreting cells are recorded from a number of animal groups, notably opisthobranch gastropods, where they are concluded to possess a defensive function. Such a structure has not hitherto been recorded from the Bivalvia.
Responses to pulsed light stimuli in a pulmonate slug (Limax pseudoflavus)
Authors: Ford D. J. G. , Cook A. 
Published: March 2009

The phase changes in the activity rhythm of the pulmonate slug Limax pseudoflavus caused by light pulses (30 min, 10,000 lux) in otherwise dark conditions were recorded using time lapse cinematography and tipping aktographs. From the timing of the pulse relative to an individual activity cycle a phase response curve was constructed. Phase delays occurred when the pulse was administered in the early subjective night and subjective day, phase advances were recorded during the mid and late subjective night.The effects of two pulses (30 min, 10,000 lux) forming symmetric and asymmetric skeleton photoperiods were also recorded and related to the phase response curve. Both stable and unstable entrained states were found, the condition being dependent upon the relative timing of the two pulses and the previous activity onset. It was also shown that there was a time lag between the light pulse and its expressed phase setting effect. Thus phase setting is not instantaneous as with some insects.
A rhizocephalan (Crustacea; Cirripedia) infestation of the deep‐sea galatheid Munida sarsi (Crustacea; Decapoda), the effects on the host and the influence of depth upon the host‐parasite relationship
Authors: ATTRILL M. J. 
Published: March 2009

Three species of rhizocephalan barnacle were found to be infesting 293 specimens of Munida sarsi Huus from the Porcupine Sea‐bight (49–52°N, 11–14°W): Tortugaster boschmai, Lernaeodiscus ingolfi and, by far the most common, Triangulus munidae. Each species was found to have its own preferred abdominal segment site of emergence and particular effect on both male and female host pleopod structure. Triangulus munidae, however, caused a series of pleopod structure forms which led to the definition of a range of pleopod ‘Types’ for male and female hosts, including a peculiar masculinization of the female hosts' pleopods. The hormonal mechanisms behind these modifications are discussed.Depth was found to have an influence upon the host‐parasite relationship, there being both an increase in the percentage infestation of M. sarsi and a decrease in the effects of T. munidae on the host's pleopod structure with an increase in depth. At extremes of their bathymetric ranges, the host becomes more susceptible to infestation, while the effect of the parasite on its host breaks down.
On the synchronization of breathing with running in wallabies (Macropus spp.) and horses (Equus caballus)
Authors: ALEXANDER R. McN. 
Published: March 2009

Previous investigations have shown that, when they run, wallabies and various quadrupedal mammals take exactly one breath per stride. It has been suggested that their breathing movements may be driven by the movements of running, and three mechanisms have been proposed: the lungs may be compressed and expanded by vibrations of a ‘visceral piston’, by bending and extension of the back or by the forces imposed on the rib cage by the forelegs.The three mechanisms are tested against published observations on wallabies and horses. Simple mathematical models are used to predict the phase relationship between running and breathing for each mechanism, and the amplitudes of breathing that they could cause. The observed breathing movements of hopping wallabies are consistent with a visceral piston mechanism tuned to the stride frequency, but cannot be explained by either of the other mechanisms. Those of cantering and galloping horses are not consistent with a tuned visceral piston mechanism, but could be driven by the bending and extension of the back.
Photoperiodic effects on post‐weaning growth and food consumption in the collared lemming Dicrostonyx groenlandicus
Authors: REYNOLDS P. S. , LAVIGNE D. M. 
Published: March 2009

The effects of long ‘summer’ (22L:2D) and short ‘winter’ (2L:22D) photoperiod on post‐weaning growth and food consumption of the collared lemming were examined. Growth was described by Gompertz equations. After 10 weeks, lemmings maintained under short photoperiods developed white winter pelage and heavy bifid claws; body mass and estimated asymptotic mass were significantly greater than for lemmings reared under long photoperiod. Sexual dimorphism in body size was observed within treatments, males growing larger than females. There were no significant differences in the overall growth rate constant k as a result of either sex or photoperiod treatment. However, instantaneous growth rates (dW/dt) were significantly higher in ‘winter’ lemmings. Mass at weaning was a significant determinant of adult mass at 90 days.Cumulative food consumption at 90 days was not significantly different between photoperiod groups, even though ‘winter’ lemmings gained more than double the mass of their ‘summer’ counterparts over the post‐weaning period. Increased gut length observed for winter morphs may act as the physiological mechanism promoting greater gross energy efficiency.The present study suggests that the overwintering strategy of the collared lemming with respect to body mass changes and energy requirements differs considerably from that of other microtines.
The anatomy of some new archaeogastropod limpets (Superfamily Peltospiracea) from hydrothermal vents
Authors: FRETTER VERA 
Published: March 2009

The anatomy is described of seven new species of limpet from hydrothermal vents in five new genera in the new family Peltospiridae, new superfamily Peltospiracea (McLean, 1989). Distinguishing external features are: (1) the tapering snout; (2) no eyes; (3) epipodium with tentacles variously modified; (4) deep mantle cavity; (5) single left bilamellate gill with pectiniform skeleton; (6) separate sexes; (7) no copulatory organ; (8) mantle edge with two folds, the outer secreting the shell with an inturned rim of periostracum, the inner sensory and differing in detailed structure of the secreting areas.Limpet form is attained by the anterior migration of the posterior viscera into the mantle skirt on the right side. On the left is the single kidney, with monotocardian characteristics, followed posteriorly by the auricle and then the ventricle (not traversed by the rectum), which marks the posterior limit of the mantle cavity. The auricle receives blood from a pallial as well as a ctenidial circulation. There is no right kidney but a pallial excretory organ opens right of the rectum.The radula is rhipidoglossate. The alimentary canal resembles that of a primitive prosobranch though with an odontophore indicating more powerful action, a subradular organ protrusible through the mouth and held in position by the tapering snout, and paired oesophageal pouches providing the most voluminous cavity of the body.The gonadial duct acts as a vesicula seminalis in the male, and in the female opens into the kidney, the external opening of which is, in this sex, urinogenital. A second, receptacular duct, pallial in origin, connects with the ovary, opening to the mantle cavity near the anterior limit of the shell muscle and receiving seminal fluid emitted from the pallial vas deferens. Sperm are discharged directly into the ovarian duct, viable ones are stored and effete ones digested. The anatomy indicates that fertilization is internal. A levator muscle regulates the position of the openings of the gonadial and receptacular ducts within the ovary. It originates alongside the median margin of the right limb of the horseshoe‐shaped shell muscle.Relationships with other vent limpets are discussed.
Environmental effects on activity and honeydew collection by the weaver ant Polyrhachis simplex (Hymenoptera: Formicidae) when attending the mealybug Trabutina sp. (Homoptera: Pseudococcidae)
Authors: DEGEN A. A. , GERSANI M. 
Published: March 2009

The amount of honeydew collected by the weaver ant Polyrhachis simplex (Hymenoptera: Formicidae) was measured when it attended the mealybug Trabutina sp. (Homoptera: Pseudococcidae). Measurements were made in a relatively cool month (March; mean daily minimum and maximum air temperatures while the ants were active were 17 °C and 23 °C, respectively), a warm month (April; 18 °C and 28 °C) and a hot month (May; 20 °C and 35 °C). The Trabutina sp. were located on a tamarisk tree. No byres were made by the ants around Trabutina sp. clusters in March, initial byre stages were noted in April and many byres were found in May. In March, maximum ant activity was at midday, the hottest part of the day, whereas in April and May there were troughs of activity at that time. In May, the trough was more pronounced than in April and activity was high in the early morning while it was low in April. Honeydew fresh matter collected by the ants was significantly negatively correlated with air temperature and positively correlated with relative humidity. Dry matter collected was not significantly correlated with any of these two variables and showed no difference throughout the day or among months. Within months, the least amount of honeydew fresh matter was collected at the highest air temperatures and at the lowest relative humidities and, among months, the least was collected during the hottest month. It was postulated that evaporative water loss of the ants increased with high air temperature and low relative humidity. Activity and honeydew collection by the ants was highest in April. During March, 3372 ants entered the nest daily with 2900 mg dry matter of honeydew, during April, 8157 ants entered daily with 6933 mg and during May, 6207 ants entered daily with 5152 mg. This daily honeydew intake had an energy content of 51 1 kJ, 122.3 kJ and 90.9 kJ in the three months, respectively. Each Trabutina sp. attended by ants excreted 0–51 mg dry matter of honeydew per hour, whereas each unattended Trabutina sp. excreted 012 mg dry matter per hour.It was concluded that P. simplex used both behavioural and physiological mechanisms in coping with the environment. During cool months they increased their activity at the hottest part of the day. During hot months they reduced their activity during the hottest part of the day and they either remained in their nests, where the air temperature was lower and relative humidity was higher, or many ants remained in byres protected from much of the solar radiation. Those ants that were active during the hottest part of the day increased their evaporative water loss.
Life‐history characteristics and sexual strategy of Mytilopsis sallei (Bivalvia: Dreissenacea), introduced into Hong Kong
Authors: Morton Brian 
Published: March 2009

First recorded from Hong Kong in 1980, Mytilopsis sallei now dominates the intertidal pier community within the Government Dockyard, Victoria Harbour. Analysis of monthly samples of M. sallei has demonstrated aspects of the reproductive strategy and life‐history characteristics correlated with seasonal changes in local water quality. Mytilopsis sallei is dioecious, has a high fecundity, matures early (at 8–10 mm shell length), grows fast and the majority of the population is probably semelparous. These are characteristic traits of opportunistic r‐strategists. Comparable characteristics are typical of other introduced bivalves. Maximum life span of M. sallei in the Dockyard is probably less than 20 months with, however, most of the population dying before that. Heavy recruitment, particularly during spring‐summer, suffocates older individuals. The shells of dead animals similarly last for little more than one year, dissolution and crushing effecting this. A mat of byssal threads serves to bind the mass and anchor it to the substratum. Mytilopsis sallei exhibits two periods of reproductive activity and settlement per year. These are possibly two elements of a single recruitment divided into minor (autumn‐winter) and major (spring‐summer) components by either high summer temperatures or low salinities. Summer and winter recruits of M. sallei, respectively, mature to produce the summer and winter juveniles of the following year. Over‐stepping generations plus survival of a few individuals into their second year thus ensure continued success of M. sallei, and account for its spread and dominance in its introduced range. Such a bimodal pattern appears typical of many Hong Kong intertidal, estuarine and freshwater bivalves.
Behaviour of the yellow‐eyed penguin chick
Authors: Seddon Philip J. 
Published: March 2009

The ontogeny of yellow‐eyed penguin (Megadyptes antipodes) chick behaviour follows the order of development determined by Nice (1962) for several species of birds, and by Spurr (1975) for the Adélie penguin (Pygoscelis adeliae). Feeding and comfort behaviours are the first to develop, followed by locomotion and aggressive behaviour.Active solicitation of food may occur at one day of age. Chicks initially use non‐visual cues to mediate begging. After their eyes open on the third or fourth day there is an increase in the use of visual stimuli, and begging occurs most often following adult nest relief. Sibling rivalry is not intense, occurring least during feeding, and in general both chicks are fed at each session.The chicks are brooded for the first 21–25 days. At sparsely vegetated nest sites overheating may occur after 21 days and down‐covered chicks will seek shade and pant in hot weather.Throughout the 6–7 weeks of the guard phase there is a decrease in the amount of time spent resting in a prone posture, and an increase in exploratory, locomotory behaviour. During the post‐guard phase, and until fledging and independence at 15 weeks after hatching, chicks may wander up to 20 m from the nest bowl during exploration, shade‐seeking and feeding.Adults feed only their own chicks, and chicks appear to beg only from their parents. Dense vegetation and long distances between nests tend to restrict contact between adults and chicks from neighbouring nests, and prevent the formation of large chick crèches.
The effect of scavenger mutilation on insect succession at impala carcasses in southern Africa
Authors: Ellison G. T. H. 
Published: March 2009

Two impala (Aepyceros melampus) carcasses were subjected to varying degrees of mutilation by large mammalian scavengers.Daily observations of carcass surface condition revealed that the timing and frequency of scavenger feeding visits had a profound effect upon carcass decomposition: a single feeding visit 10 days after death at the first carcass produced an extended sequence of decay. At the second carcass, repeated visits two, three and five days after death, resulted in a faster rate of decay.The colonization of the carcasses by necrophagous insects was characterized by a distinct sequence of arrival. The abundance of Calliphoridae, Histeridae and Dermestidae was correlated with surface condition at both carcasses. Thus, these insects provided an indication of the state of carcass decay. However, as the rate of decomposition was different at each carcass, the temporal abundance of necrophagous insects was not the same at both carcasses.The results suggest that the temporal abundance of key insect families provide an inaccurate indication of the time of death in circumstances when carcasses have subsequently been mutilated.
The colony structure and dominance hierarchy of the Damaraland mole‐rat, Cryptomys damarensis (Rodentia: Bathyergidae), from Namibia
Authors: Jacobs D. S. , Bennett N. C. , Jarvis J. U. M. , Crowe T. M. 
Published: March 2009

Cryptomys damarensis is one of the few subterranean rodents which is social. This species is found in the semi‐arid regions of southwestern and central Africa. The Damaraland mole‐rat occurs in coloniesof up to 25 individuals, in which reproduction is limited to one or two of the largest males and the largest female in the colony.The mean colony size is 18 mole‐rats (n=6 colonies). The mean colony biomass is 2.32 kg and the sex ratio is female biased (0.71–0.78). The number of mole‐rats in each colony, the mean body mass and the sex ratio are described for six field‐captured colonies, three of which were captured in their entirety.The dominance hierarchy of two colonies of C. damarensis was found to be linear with a value of between 0.94 and 1.00 calculated from Landau's linearity index. Dominance was found to be related to gender, with the males more dominant than females. The reproductive individuals are the dominant animals within each respective gender. The non‐reproductive females rank lowest in the hierarchy.