摘要:

The prey detection methods of 12 species of Carabidae and one species of Staphylinidae were investigated using video and orientation techniques. The species examined wereCicindela campestris, Cychrus caraboides, Carabus problematicus, C. violaceus, Calosoma maderae, Nebria complanata, Scarites abbreviates, Broscus cephaloles, Pterostichus madidus, P. melanarius, P. niger, Abax parallelepipedusandStaphylinus olens.All the species examined were seen to respond to prey upon contact (either by tactile or gustatory reception) during locomotor activity. Tests using orientation chambers showed that some of the species would orientate towards prey in the absence of contact. Some species orientated using vision (C.campestris, C. maderae, S. abbreviates, A. parallelepipedus). This was most frequent when tested with fast‐moving prey. In others, orientation towards prey occurred when olfactory cues were available(P. madidus, P. melanarius, P. nigerandA.parallelepipedus). All of the species employing this method of prey detection belonged to the Pterostichini and it appears that the receptors involved are situated on the antennae. Although some species did not orientate towards prey in the absence of contact cues, some of these species were found to respond to slug mucus (C. caraboides, C. problematicus, C. violaceusand S.abbreviates). The receptors for this are probably situated on the terminal ends of the palps. The method of prey detection used is discussed in relation to the ecology of the specie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02531.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The development of ovarian follicles in a skink has been studied with light and electron microscopy. In early stages the previtellogenic oocyte has a follicular covering (granulosa) comprising only two cell types, small cells and pyriform cells. A complex microvillous interdigitation between follicle cells and oocyte is present from very early stages but regresses as a mature size is reached. The outer thecal layer differentiates into distinct interna and externa as growth proceeds. Occasional biovular follicles are formed. Pyriform cells establish direct continuity with the oocyte via cytoplasmic bridges which traverse the layer of microvilli interdigitating in the zona pellucida. Such bridges appear most frequently just before the onset of yolk deposition; the organelles and cytoplasmic constituents presumed to be transferred across them may stimulate this activity. As the follicles grow, the pyriform cells shrink and disappear to leave just the small cells forming the single layered granulosa. There is asynchrony in recruitment and/or early growth rates of follicle crops and uniformity of oocyte size appears only as vitellogenesis nears completion (with up to five oocytes, about 1 cm in diameter, on each side). Yolk deposition may involve transformation of golgi vesicles or pinocytotic vesicles but there is no evidence to show mitochondria as foci for deposition.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02532.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The dynamics and mechanical forces generated during burrowing inPolyphysia crassa(Annelida: Polychaeta) andPriapulus caudatus(Priapulida) were investigated. Both animals live in soft marine muds and burrow by utilizing a direct peristaltic wave alternating with a high internal pressure event which thrusts the anterior part of the body into the substratum. Forces generated during the various phases of a typical burrowing cycle were measured in animals moving beneath the natural substratum at 5±3 °C using electronic transducers and recorder. During ‘head’ advancePolyphysiagenerated 0.027 N, and during ‘tail’ advance 0.020 N, with peak internal pressures averaging 0.95 kPa (= 0.095 N/cm2). Force byPriapulusduring head advance and tail advance was 0.081 N and 0.121 N, respectively, with peak internal pressures averaging 2.47 kPa (= 0.247 N/cm2).Polyphysiamoves more slowly (0.24 cm/min) than doesPriapulus(0.76 cm/min) and expends more energy on mass moved per unit distance. These force measurements during a burrowing cycle were used in place of respirometry as a basis for computation of net cost of transport (NCT) for each animal. NCT forPolyphysiawas 635 J kg‐1m‐1and forPriapuluswas 314Jkg‐1m‐l. Cost of transport for all burrowing animals thus far investigated is high compared to swimming, running and flying. For soft‐bodied invertebrates that live an entirely buried existence this high cost must be interpreted in the broader context of the adaptive value of infaunal life, especially protection against predation, and not as simply a me

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02533.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Seasonal breeding of non‐hibernating small mammals is generally associated with a reduction in body weight during the non‐breeding period. In aseasonal breeders and in exceptional situations, when winter breeding occurs, this pattern cannot be found.The reduction in body weight is thought to be a means to reduce energy requirements during the harsh non‐breeding season that can either be winter, in the Holarctic, or the dry season in the Transvaal highveld.The controlling mechanism in the strongly seasonal subtropical environment in southern Africa seems to be photoperiod as in small mammals from the northern hemisphere.Since a general agreement in body weight changes was found in rodents and shrews from both areas, further similarities in adaptations to strongly seasonal environments in the subtropics are expected.For the first time it is shown that the adaptive responses of small mammals to unfavourable seasons are similar in the Holarctic and seasonal subtropical

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02534.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Feather fragments collected from the head of the Oxford specimen of the dodo were examined with light‐ and scanning electron microscopy. The material proved to be heavily abraded but still yielded characteristics from which some conclusions on feather type and taxonomy can be drawn. The microstructure of the barbules examined indicates that the fragments belong to the pennaceous feather type. The feathering shows some characters apparently peculiar to the dodos. In other respects the feather structure is more similar to that of the Columbidae than that of the Rallida

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02535.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The allometric relationships between body size and several aspects of wing morphology in the insect order Hymenoptera were investigated using multivariate morphometric techniques. The study focused primarily on wing allometry in five monophyletic genera of bees (Perdila, Halictus, Ceratina, TrigonaandApis), but the patterns of size‐related evolutionary change found within each of these genera are also found to exist in numerous other hymenopteran taxa. Increased body size in hymenopteran lineages is correlated with the following changes in wing morphology: (1) decreased relative stigma area, (2) distal extension of wing vein elements, (3) increased aspect ratio and (4) proximal shift in the centroid of wing area. The reverse is true for decreased size. The widespread allometric trends most likely result from adaptive change in wing morphology due to size‐related changes in the physical properties impinging on the organism–principally the quality and magnitude of drag. The fact that similar wing morphologies among distantly related species can result from similarity in body size has important implications for the study of hymenopteran phylogeny, especially at lower taxonomic levels and when a high proportion of wing characters are emp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02536.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The circumtropical gobiid fish genusBathygobiusBleeker, 1878 is discussed and defined in terms of external features, including the head lateral‐line system, and osteology. Three West African species are recognized and redescribed: the amphiatlanticB. soporalor(Valenciennes, 1837) and two endemics,B. burtoni(O'Shaughnessy, 1875) andB. casamancus(Rochebrune, 1880). West AfricanB. soporatordiffers significantly from western Atlantic material only in average values for predorsal scales and some body proportions, so that separation of eastern and western Atlantic populations as morphological species is not warranted. The affinities of the West AfricanBathygobiusspecies are examined by means of phenetic (presence‐only group‐average clustering) and cladistic (Camin‐Sokal, Dollo and Wagner) numerical processing of a binary database comprising 46 character states in 15 Operational Taxonomic Units (OTUs) formed by species ofBathygobius.Results do not indicate close common ancestry between the West African endemic species andB. soporator, which has probably colonized West Africa from the New World. The implications of various cladistic schemes for the relationships of certain other American species are als

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02537.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02539.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02540.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02541.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY