摘要:

The development ofPomatoleios kraussiiis extremely similar to that ofPomatoceros triqueter, and is completed under laboratory conditions in 1–3 weeks at 25–27°C. Mature larvae settle and metamorphose preferentially on the shells of adult conspeci

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04178.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The monostratified clitellar epidermis ofLumbricillus rivalisconsists of supporting cells, granular secretory cells, and globular secretory cells, together with the acid mucous cells typical of normal skin in the anterior and posterior transition zones. The secretion of the granular cells is a neutral glycoprotein with low levels of bound lipid, and that of the globular cells is a sulphated acid mucopolysaccharide lacking detectable protein or lipid.Ultrastructurally the granular cells possess 1 μm, membrane‐bound granules of variable electron density suggestive of maturation changes. The formative granules arise from Golgi vesicles and are moderately electron translucent. They contain parallel‐aligned, tubule‐like inclusions of 14 nm diameter, observed also in the mature regions of the Golgi. Granules in the mid or apical part of the cell show increased electron density, the formative pattern being wholly or partially obscured and the subunit alignment, when discernable, no longer uniform. Moiré fringe patterns are evident in some granules. The patterns and electron density are lost after pronase digestion. The globular cells contain electron translucent, membrane‐bound globules of 2–3 μm diameter with finely fibrous contents. They arise from mature Golgi vesicles and are unaffected by pronase treatment.The results suggest that the granular cells secrete the cocoon wall and the globular cells the material that surrounds the developing embryos, and are compared with published accounts of other microdrile clitella and with those of the clitellum of lumbrici

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04179.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Odonata found during two visits to Mole National Park in Northern Ghana during 1974 and 1975 are listed, with brief notes on their habits and ecology, and these are compared with similar observations, published and unpublished, from areas of similar latitude in the Ivory Coast and Nigeria.In an appendix descriptions and figures are given of simple means of separating species that are not readily distinguishable by reference to the published literature.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04180.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

In eutherian mammals, foetal growth shows a straight‐line relationship between time and cube root of foetal weight. The same relationship has now been found to hold for the embryos in birds' eggs and is postulated for reptiles. In marsupials the specific foetal growth rate does not exceed that already known for the higher primates. Outside the eutherian mammals, only the birds have developed high embryonic growth rates, but in exchange for other disadvantage

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04181.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The manner in which the porosity of avian eggshells varies with egg weight is discussed in relation to the number of pores, their cross‐sectional area and length. Shell porosity and ways in which this can change to satisfy different environmental demands are discussed on the basis of a simple model which envisages the shell as being composed of columns of calcit

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04182.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Behaviour of chaetodontid fishes relevant to Lorenz's “poster colouration” hypothesis has been studied. Field observations of 20 species at Lizard Island, Great Barrier Reef, showed that these chaetodontids rove over large areas of reef, occurring singly or in pairs and sometimes sizeable groups. The behaviour of chaetodontids does not support the supposed explanation of poster colours as intra‐specific sign stimuli serving to space individuals. During daytime, agonistic encounters are rare, even amongst groups, and for most species there is no evidence of territoriality. Experiments presenting painted and blank chaetodontid models to eight species generally confirmed these observations. At dusk and dawn, chaetodontids are aggressive and defend regular night‐resting places. Agonistic encounters though, are both intra‐ and inter‐specific; they serve to space individuals over only very small distances, and colouration seems to have little warning value. The question of the functional significance of poster colours remains largely unsolved. Amongst chaetodontids, territoriality clearly is not a major function and the evidence suggests that other kinds of social communication, as well as predator avoidance, have probably been important in the evolution of poster

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04183.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

In Morocco,Pterocles alchataandorientalisprefer steppe habitats, whilecoronatus, senegallusandlichtensteiniprefer deserts, so that these species groups are largely allopatric under normal climatic conditions. Both habitats impose extreme thermal conditions (air temperatures up to 55°C) on these diurnally active birds which characteristically nest in the open. Sandgrouse minimize environmental and metabolic heat loads by concentrating vigorous activity into the cooler parts of the day, by remaining inactive when the sun is high, and (exceptionally among the bird species studied) by increasing thermal insulation when ambient temperatures exceed body temperatures. Water conservation is achieved by delaying evaporative heat dispersal mechanisms (gular fluttering and gaping, but not panting) until air temperatures reach 50°C, and probably also by a renal‐colonic system adapted to oliguria and salt retention. Desert and steppe study sites had permanent and comparatively fresh water supplies, but appeared to be salt deficient. Morning drinking flights inalchataandorientalisshowed evidence of a “feed forward” response enabling increasing numbers of birds to drink earlier in the day in anticipation of hotter conditions later.P. coronatus, senegallusandlichtensteinibreast feathers are adapted for water transport (we have no data foralchataandorientalis), and show specializations in keratin‐water interactions (not seen inMelopsittacus undulatusorC. coturnix) enabling more rapid feather wat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04184.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A test is described which permits the determination of the respiratory rate of the insect to respond to, and recover from a short series of temperature changes. Both the transient and steady state respiratory responses were studied in the pupa, male and female of four species of tropical butterflies,Heliconius melpomeneLinn.,Papilio demoleusWallace,Danaus chrysippusLinn., andHypolimnas bolinaFabr., following a decrease and then an increase in environmental temperature.Primary data consists of weight, oxygen consumption, and duration time of the transients; secondary data calculated from the above consisted of the Respiratory Change Ratio (RCR) and the % Recovery.The RCR values were similar in pupa, male and female within a species, but showed significant differences between species,H. melpomeneshowing least change for a 10°C temperature change andH. bolinamost. The ability to recover varied within and between species. InD. chrysippusthere was no difference between pupa male and female; inH. bolina, pupa, male and female differed significantly in this.Heliconius melpomeneshowed very poor recuperative powers.The most notable difference in the transients was the slow change following a drop in temperature compared with the instant increase to the steady state value following an increase in temperature. The duration of transients for body temperature were the same for both an increase and a decrease. The respiratory rate of the animal and its body temperature are clearly uncoupled during this period.The transition of the respiratory rate associated with a decrease in temperature showed a smooth curve for the pupa but a momentary increase occurs in the adult.A hypothesis is proposed to account for these results and their possible significance in the distribution and choice of a habitat by the butterflies discussed

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04185.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Features of the shell which can be used for aging Roman snailsHelix pomatiaL. are described. Field evidence suggests that growth breaks in the shell correspond to resting periods during the winter in the juvenile phase of shell growth. The microstructure of the shell is described and the structure of the juvenile breaks and layering in the lip of the adult snail are shown to be similar. It is concluded that the two are analogous, that the layers at the lip are annual, and that it is theoretically possible to trace the adult shell back to the year of hatching. In practice, errors may be made in recording, but the method can be of great value in population studies.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04186.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY