摘要:

In the newt,Triturus cristatus carnifex(Laurenti), the spleen normally contains a reserve of erythrocytes which varies according to the respiratory condition of the animal. In chlorobutanolanaesthetized specimens, histological analyses andin vivoobservations following the injection into the bloodstream of fluorescent microspheres 10 μm in diameter (FluoresbriteTMYG, Polysciences Inc., USA) show that, in steady conditions, the stored red blood cells are not segregated in the spleen but pass through the organ with a very slow flow; their time of transit in a spleen maintained in a state of maximum congestion is 41.5 ± 14.2 minutes (mean ± standard deviati

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05385.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The energetics of lactation in grey seal females and their pups was investigated using labelled water methods. Average total energy output (maternal maintenance energy expenditure plus milk energy output), from the estimated change in total body gross energy, of 15 females was 99.8 MJ/d (S.E. 2.5), which was nearly 30% lower than previously published estimates. In seven females, energy output was partitioned into milk energy output plus maternal maintenance energy expenditure. Average investment in milk was 69.7MJ/d (S.E. 5‐0), and lactation costs accounted for 70% of total maternal energy output. Average daily maternal maintenance energy expenditure (heat output) of the same seven females was 30.0MJ/d (S.E. 5.0), which was equivalent to 2.3 times the basal metabolic rate predicted from Kleiber's (1975) allometric equation. In seven pups, milk consumption rates were measured isotopically and these averaged 3.0kg/d (S.E. 0.2). In four pups energy expenditure, measured using doubly‐labelled water, averaged 13.5MJ/d (S.E. 1.2), equivalent to 3.7 times the basal metabolic rate predicted from Kleiber's (1975) equation. All females were in negative water balance during lactation which was associated with loss of tissue during fasting. Mean water efflux was 3966ml/d (S.E. 286) and mean water influx was 2677ml/d (S.E. 245), but there was no evidence that females are dehydrated during lactat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05386.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The accuracy of five different methods used in spraint analysis for extimating prey proportions is tested through a feeding experiment with three otters in captivity. Estimated prey proportions are copared to the actual diet of the otters. The results of analysing 362 spraints and the time budget indicated a score‐bulk estimate to be the most appropriate method of estimating prey diet and it is concluded that dietary studies using different methods can be compared in broad outlines. The relatins between the methods are confirmed in the analysis of 978 spriaints, collected in the fiel

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05387.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Carcinus manenas, Liocarcinus puberandCancer pagursare thought to be three likely crab predators of the gastropodCalliostoma Zizyphinum.In order to compare the strenghts of predators and their prey, the whole shell and aperture lip strengh of white and pinkCalliostomamorphotypes and the maximum forces exerted by the chelipeds of three crab species were measured. Although white shells were thicker than pink shells,Calliostomacolour morphotyes did not differ significantly in either the force required to break the shell lip or the whole shell. BothLiocarcinus puberandCarcinus maenashave dimorphic chelipeds and their “crusher” chelipeds deliver almost double the forces generated by the‘cutter’chelipeds. In constrast,Cancer pagurushas monomorphic chelipeds both delivering similar forces.When compared withCalliostomashell strenght, the forces generated by the‘crusher’chelipeds of mostL. pubertested were, in general, sufficient to break the shell lip ofCalliostomashells, whereas forces generated by the‘cutter’chelipeds of only the larger individuals were sufficient to break the shell lip. InC. manenas, forces generated by both the‘cutter’and‘crusher’chelipeds often exceeded the minimum recorded force required to break the shell lip and the‘crusher’cheliped reached the minimum force required to break wholeCalliostomashells. Both chelipeds of allC. pagurustested generated forces in excess of the minimum required to break the shell lip, and the proportion of individuals capable of generating the minimum force required to break the whole shell increased with the size of the size of the crab.Carcinus maenasandCancer paguruswere capable of breaking both the shell lips and the whole shells of a wider range

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05388.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY