摘要:

The growth of the Antarctic fur sealArctocephalus gazellaat South Georgia is described from 556 specimens whose age was determined. The following parameters are described: standard length, body weight, foreflipper length, hindflipper length, neck girth, axillary girth and blubber thickness. Data are also presented on absolute and relative sizes of the following organs in new‐born pups, pups near weaning, two‐year‐olds and adults: thyroids, adrenals, heart, lungs, kidneys, liver, spleen and brain.The growth of the pup within the 110–115 day suckling period is estimated as 98 g/day for males and 84 g/day for females. No other species of fur seal grows so rapidly at this time. Subsequent growth is compared with that of the other species of fur seal to inhabit polar water,Callorhinus ursinus. A. gazellagrows more rapidly up to age three, and although adult males are smaller, females are slightly larger. This more rapid initial growth, and earlier breeding, may be related to the large reduction in the Antarctic stocks of baleen whales which eat the same food.The mean weights of males, females and all individuals in the population are calculated as 54‐8,25‐3 and 39‐3 kg respectively. The number in the population at the end of the breeding season is 41 times the number of pups born, equivalent to a total population in March 1976 of 369,000 seals with a biomass of 14,500 tonnes and an annual food consumption of about 3

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07709.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The structure of the sensilium of fleas has been investigated by light, stereoscan and transmission electron microscopy.This compound sensory structure, which occurs in both sexes, is positioned on the terminal segments and superficially comprises a saddle‐shaped cuticular plate covered with microtrichia between which are dispersed a species‐specific number of pits (16–100) each with a long hair arising from its centre. The cuticular pit is made of two chambers each supported by vertical septa. The apertures in each chamber through which the seta passes vary in diameter allowing an angle of flexure of the hair.Observations of cellular detail indicate features common with other insect mechano‐receptors, a bipolar neuron making contact with the hair base. The dendrite is divided into distal and proximal segments by a ciliary region in which can be seen supporting scolopale rods. The scolopale cell, the trichogen and tormogen cells ensheath the sensory neuron. The tormogen cell is large and one is characteristically associated with each pit. During development it withdraws from the hair leaving a large extracellular cavity into which protrude numerous microvilli.InCeretophyllus styxsecretion is found in this extracellular cavity during the Spring period prior to the return of the migrant host.The tormogen cell wraps around the neuron and is thought to give support to the hair base/neuron (= tubular body) junction giving a measure of increased sensitivity to the system. This sensitivity, it is suggested, could be increased by the presence of the extracellular secretion which is serving to hold the system rigid, any movement of the hair being passed on to the neuron.C. styxoverwinters in a cocoon emerging in the Spring when its migrant host returns. On emergence the system, sensitised by the presence of the secretion, can now be used for the detection of the returning host by mechanical means and/or during the mating process, aligning male with female. Ceratophyllid fleas are known to mate on emergence without the necessity of a blood meal.Having mated removal of the fluid would make the hair base/neuron junction less sensitive.If the interpretation of the results is accepted and the presence of fluid inC. styxat least, is a physiological feature at certain times of the year, then two possible roles exist:(1) That the sensilium is used to detect the presence of the returning host.(2) That, having emerged from the overwintering cocoon, the sensilium is then used in the mating

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07710.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The structure of the cochlea had been studied by serial sections in 13 species of mammals, with representatives from the metatherian order Marsupialia and the eutherian orders Insectivora, Primates, Edentata, Pholidota and Carnivora. All the specimens have been intra‐vitally perfused to obtain good preservation of the cochlea. The height of the cochlea was measured and the number of half‐turns noted in each cochlea. Other measurements were made at every half‐turn of the cochlea in the modiolar plane as follows: the width of the cochlea and the radial position of the spiral organ, the width and thickness of the basilar membrane, the height of the cells of Claudius and the size of the spiral ligament. Other special features were also obs

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07711.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

In north‐east Scotland most Stoats turned white in winter, whereas in south‐west Scotland most were pied and in north‐east England few changed colour. These differences were associated with regional differences in the number of days of snowfall and snow‐lie, and in monthly minimum temperature, but not with mean temperature or e

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07712.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The Small Indian mongoose in Fiji is sedentary, solitary and has overlapping home ranges. It is highly predaceous with 60 % by weight of the prey being vertebrate. It is argued that while social groups in cats, hyenas and dogs allow exploitation of large prey, in viverrids they allow group defence.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07713.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The true crabs or Brachyura can be divided into a primitive section with integumental spermathecae unconnected with the oviducts, and an advanced section with spermathecae formed as dilations of the oviducts: no intermediate forms are known. Previously the Raninidae, one of the primitive families, has been considered to have a single median sper‐matheca, as in the presumed ancestral Astacura. This conflicted with their generally more evolved condition compared to the other primitive families. This investigation shows that the basic raninid structure is as in other primitive crabs, with paired spermathecae lying within endosternite 7/8. Due to the acute dorsal flexion of the posterior sternites the spermathecae have come to open anteriorly on sternite 7 rather than on sternal suture 7/8, and due to narrowing of the sternum the paired openings may appear as a single median one. This revised structure confirms the Raninidae as the most advanced of the primitive Brachyura, but unfortunately does not contribute to an understanding of the course of evolution of the spermathecal condition in the advanced Brachyur

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07714.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

From the point of view of adaptation for flight in bats, we compared growth and LDH (lactate dehydrogenase) isozyme patterns in the pectoral and cardiac muscles of the Japanese Lesser horseshoe bat,Rhinolophus cornutus cornutus.In the pectoral muscles, the four LDH isozyme bands were recognized throughout life. In the embryo and newborn young the predominant isozyme was LDH‐3 and the relative amount of LDH‐1 was very low. The predominant isozyme of the infant in the flying stage was LDH‐1.Moreover, the percentage of B subunit of LDH isozymes in the pectoral muscles increased remarkably during the transition period from the flapping to flying stage. Thus, it is concluded that there is a reversal of LDH isozyme activity toward more anodal side (cardiac muscle type) during the transition period, which is regarded as an adaptation to the metabolic requirement at isozyme level of the pectoral muscles for an adult. This species has a highly manoeuvrable flight with low speed, like that of a butterfly. On the other hand, most of the activity in the cardiac muscles, even in the embryo, was concentrated in more anodal isozymes with LDH‐1 and LDH‐2, and consequently the percentage of B subunit showed a considerably higher value, which continued to increase gradually until the ad

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07715.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

An investigation was made to compare the reproductive strategies ofCrenilabrus melops, Labrus bergylta, Labrus ossifagus, Centrolabrus exoletusandCtenolabrus rupestris.Fish were collected monthly and measurements were made of length, weight, age and colouration. Histological sections of the gonads were also prepared.Labrus bergyltaandL. ossifagusare protogynous, the former monandric and the latter diandric, and a distinct colour change is associated with sex‐inversion inL. ossifagus.The other three species are gonochoristic and onlyC. melopsexhibits sexual dimorphism which involves body colouration and size of the urino‐genital papilla.All five species undergo normal annual cycles of reproduction which compare with those described for other teleost species, but some differences were noted relating to the different reproductive strategies.L. bergyltafemales reached sexual maturity at the late age of six to nine years following earlier abortive maturation.InC. melopstwo types of male were found: the normal (type 1) males and a minority group (about 20%) termed type 2 males, which have complete female secondary sexual characteristics. Type 2 males also have very large testes and attain sexual maturity two years earlier than type 1 males. Their role in reproduction is unknown.Sexual inversion inL. bergyltaandL. ossifagusoccurs by atrophy of the oocytes and the gradual development of spermatogenetic cysts throughout the gonad. Primary and secondary testes can be distinguished histologically and maleL. ossifaguswith primary testes do not seem to take part in reproduct

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07716.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Lake Sonfon lies in an isolated basin in the Sula Mountains of Sierra Leone. One hundred and two animal taxa were collected from this lake in April 1976: 78 of these have been identified to species, and all but four as far as the genus. The fauna consists mainly of animals with extensive geographical distributions, indicating that they have wide dispersal capacities. Three of the rotifers have not previously been recorded in Africa, and are known only from the Americas. The lake is characterized by a low conductivity and low pH. These two factors influence the fauna. Snails are absent, rhizopods are abundant, and so are rotifers of the genusLecane, while the genusBrachionusis poorly represented. When compared with Debundsha Lake, a low conductivity crater lake in Cameroon, which has been studied to a similarextent, Lake Sonfon has twice as many species; this can be related to the greater diversity of habitats in Lake Sonfon.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1979.tb07717.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY