摘要:

A series ofOphisaurus apoduswas filmed while traversing plane surfaces, fields of nails and pins at different spacings, and channels of different diameter. Small individuals can practise slow lateral undulation on very rough surfaces, but with increased speed, all shift to slide‐pushing, using either constrained bends of the body or very wide swings of the tail. In fields of closely‐spaced pins, they travel by undulation, often pushing at a limited number of sites and pulling and pushing the trunk among these. Amid pins of wider spacing, the undulation involves some repositioning of curves. In channels, they utilize continuous bend concertina movement with the initial bend formed anteriorly and subsequent ones added, either to the level of the cloaca or on to the tail as well. The cloacal region cannot be established on the basis of locomotor pattern, as the propulsive waves pass smoothly from head to tail. Maximum voluntary velocities (of the centre of gravity) were 13 cm/s for slide‐pushing, 55 cm/s for lateral undulation, and 3 cm/s for concertina movement. Propulsion is entirely effected by bending of the trunk; tests gave no evidence that the dorsal and ventral portions of the integumentary armour show significant anteroposterior displacement relative to each

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04731.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

An embryonic earthworm (Oligochaeta: Lumbricidae), preserved with part of its cocoon wall by calcium phosphate mineralization, has been extracted from a deposit beneath a Late Bronze Age midden in southern England. The structure, possible identity and significance of the specimen are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04732.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The behaviours used byPholcus phalangioides(Fuesslin) (Araneae, Pholcidae) to evade its predators were studied with particular attention being given to a special defence behaviour, whirling. To whirl, this long‐legged web‐building spider swings its body around in a circle, with its legs remaining on the silk. Experiments were carried out to determine the types of stimuli that elicited whirling. Touching the spider or its web elicited whirling, as did air movement over the spider, but there was no evidence that chemical stimuli from potential predators were important. Small juveniles differed from adult females and larger juveniles by more often dropping from the web instead of whirling when confronted by a potential predator. Besides catching prey on its own webP. phalangioidesinvades other spiders' webs to catch the other spiders. By whirling in alien webs,P. phalangioidescould deter attacks by the resident spider, butP. phalangioideswas less inclined to whirl when in an alien than when in its own

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04733.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Portiais a genus of specialized web‐invading salticids that use aggressive mimicry. Some other salticids leap into webs to catch spiders but do not use aggressive mimicry.Pholcus phalangioidesis a web‐building spider with a special defensive behaviour—called whirling—in which it swings its body around in a circle while keeping its long legs on the silk.Pholcus phalangioidesis preyed on byPortiaand probably other salticid spiders in nature. Interactions betweenP. phalangioidesand 13 species of salticids were studied in the laboratory to compare how effective salticids with different styles of predation were at catching the pholcids. Four species ofPortiawere studied and each was more efficient at catchingP. phalangioidesthan were the other nine salticids tested. For one species—Portia fimbriata—individuals from three different populations were studied. The QueenslandP. fimbriataused aggressive mimicry more consistently and were more efficient at catchingP. phalangioidesthan were the other species ofPortiaand the other populations of P.fimbriata. The salticids that were the most efficient at catching pholcids were also better able to avoid setting off whirling by the pholcids. An experiment in which pholcids were artificially induced to whirl whenever the predator was near provided additional evidence that whirling is an effective defence of pholcids against predation b

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04734.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Behavioural data are provided for the first time for two species ofSpartaeus, S. spinimanusfrom Singapore and Thailand andS. thailandicusfrom Thailand. These jumping spiders (Araneae, Salticidae), from the primitive subfamily Spartaeinae, build large sheet webs on tree trunks and they capture prey—especially moths—on or near the web by walking to and lunging at them. When walking,Spartaeuswaves its palps and legs in an unusual way. In formal tests,Spartaeuscaptured moths more frequently than flies and captured both moths and flies more readily when with their webs than without their w

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04735.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Juvenile estuarine crocodiles captured insects and crabs at or above the water surface by leaps and lunges powered by the hind limbs and tail. The mouth opened as the head cleared the water; most prey were held by sidesnaps of the jaws. Such prey capture was accurate, deliberate and preceded by stalking. In contrast, submerged prey (e.g. prawns) appeared to be detected mainly by touch and detection was followed by undirected, inaccurate ‘snapping frenzies’ which were usually ineffective. Small prey items were swallowed whole under water. Large dense prey (e.g. crabs) were handled and swallowed on land or in very shallow water; large less dense prey (e.g. cockroaches) were swallowed during vigorous water‐treading in deep water, the head being maintained above the water surface.Young crocodiles ate satiation meals of 9–10% body weight (on a fresh food weight basis) at 30°C, and appetite returned over about 40 h as the stomach emptied. Total gut clearance time for a meal was 4–5 d. Evidence was obtained which demonstrated that youngCrocodylus porosusSchneider deliberately eat gastroliths from an early stage. Such gastroliths are retained within the stomach (as were barium/polystyrene spheroids of 1 mm diameter) presumably by the action of the well‐developed pyloric sphincter. X‐radiographs demonstrated that gastroliths are dispersed throughout the stomach contents after a meal and presumably aid digestion.Assimilation rates for dry mass (77.5%), energy (85.2%) and protein‐N (97.4%) were high in normal juveniles. Animals exhibiting ‘runt syndrome’ showed strong appetite but slow food processing by the gut, together with poor assimilation, especiall

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04736.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The movements of the wings during natural jumps made byTettigonia viridissimaandAmeles spallanzianawere analysed by means of high‐speed flash photography. Additional data were obtained from the bush‐cricketOecanthus pellucens. In all cases the wings were usually extended before the hind tarsi had left the ground. In most jumps the first downstroke of the wings was completed before take‐off and the wings probably contributed directly to initial propulsion. All species showed a ‘peel’ variation of the ‘clap and fling’ mechanism in the hind wing downstroke. There was evidence of strong ventral flexure in the forewing at the start of the upstroke inTettigonia. The implications of the use of the wings in the energetics of jumping

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04737.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Hastula bacillus(Deshayes) is a small terebrid gastropod which inhabits sandy surf beaches in southern Thailand, where it feeds upon spionid polychaetes. It possesses a foregut anatomy unlike that of any other gastropod. An elongate arborescent muscular organ, known as the accessory proboscis structure, is extended through the mouth during foraging. When retracted, it is folded into an ‘s’ shape in the permanent rhynchodeum. The accessory proboscis structure bears numerous tufts of short, stiff cilia which are associated with pairs or triplets of dome‐like structures. It is suggested that the structures may be chemosensory and concerned with prey location.Hastula bacillusalso possesses a retractable labial tube, a long proboscis and buccal tube, dart‐shaped radular teeth, an odontophore, an accessory salivary gland, a pair of salivary glands and a well‐developed venom gland with muscular bulb. A comparison with other terebrid species suggests thatH. bacillusis the most plesiomorphic taxon yet described from t

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04738.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

A sample of 7266 fish from 31 species was obtained from the north‐eastern Bothnian Bay, Baltic Sea, from 1975 to 1982. Twenty‐six fish species were found to be infected with seven acanthocephalan species identified asEchinorhynchus salmonis, E. bothniensis, E. borealis, E. gadi, Acanthocephalus anguillae, A. luciiandNeoechinorhynchus rutili. Acanthocephalus luciiwas the only acanthocephalan not to attain sexual maturity in at least one species of fish. Fourteen new host records were found forE. bothniensis. A total of 1576 acanthocephalan infections was found; in most cases these were single species infections, but in 108 cases infections of two, and in two cases of three species were observed.The most prominent host‐parasite relationship involvedE. salmonisandCoregonus widegreni, where the total of 11 505 worms taken from 1164 fish was roughly ten times the number of any of the other acanthocephalan parasites taken from all its hosts.Echinorhynchus gadiwas encountered only inGadus morhua. The fish of the Bothnian Bay were not considered to offer an important environment forE. gadi, E. borealis or A. lucii. Acanthocephalus anguillaewas common only inLeuciscus iduswhile the range of hosts forN. rutiliwas found to be broad with 15 of 18 infected fish species being genuine definitive hosts.Larger host fish tended to be more frequently and heavily infected than smaller ones with all acanthocephalan species except forN. rutili. Female fish were usually more heavily infected than males and the frequency distributions of numbers of acanthocephalans per fish were often observed to be overdispersed. The occurrence of non‐acanthocephalan species of helminth in the alimentary tracts of 23 species of fish was recorded during the survey. On the basis of estimates of Berger‐Parker indices, acanthocephalans were considered to be dominant in seven species of fish, cestodes in 12, digeneans in three and nematodes in one host species. Observations were also made on acanthocephalans in lampreys. The relevance of some of the findings for acanthocephalan transmission and adaptation to new environments is discusse

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04739.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The dietary importance of amphibians to otters was studied in north‐east Scotland in 1987. The proportion of amphibians identified in otter droppings varies seasonally and according to the habitat. The consumption of amphibians increases in late winter and spring while they are either hibernating or spawning. Estimations of amphibian population density at spawning sites have been carried out. There is a significant correlation between the availability of amphibians and their consumption by otters. The main amphibian species involved in the diet is the common frog,Rana temporaria(60.8%), while the common toad,Bufo bufo, represents only 1.7% of the amphibian pre

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1990.tb04740.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY