Journal of Zoology

Ma, H. H. T.; Dudgeon, D.; Lam, P. K. S.

doi: 10.1111/j.1469-7998.1991.tb06030.xpmid: N/A

Data on the population dynamics of tropical isopods in general, and those inhabiting forests in particular, are scarce. Consequently, the population dynamics of three sympatric isopods, Burmoniscus ocellatus (Philosciidae), Formosillo raffaelei and Orodillo maculatus (Armadillidae), were studied at two neighbouring sites in a mixed forest in Hong Kong between March 1985 and December 1986. Isopod population densities varied with the species, site and season, with mean densities ranging from 100–150 m‐2. Burmoniscus ocellatus and F. raffaelei had a single recruitment peak per year, while O. maculatus had two. Results of the present study revealed that air temperature was the main factor explaining seasonal variations in population density, while rainfall exerted its effect with a two‐ to three‐week time‐lag, depending on the species studied. Approximately 20% of Formosillo raffaelei and O. maculatus sampled were found infected by Rickettsiella bacteria. The possible influence of pathogens, and other biotic factors, on the dynamics of the Hong Kong isopod populations was discussed

Brown, W. A. B.; Chapman, Norma G.

doi: 10.1111/j.1469-7998.1991.tb06031.xpmid: N/A

The stages of permanent tooth development observed in radiographs of the mandible were described for known‐aged fallow deer Dama dama. Ten stages were defined and, by allocating scores for these stages, the scores that may be expected for a particular age have been identified. Lastly, the predicted age was given for total molariform scores. These were obtained, with 95% prediction intervals, from a regression of age on total molariform scores. An age assessment from tooth development stages can be made up to three years, after which, no further development takes place.

SNAZELL, R.

doi: 10.1111/j.1469-7998.1991.tb06032.xpmid: N/A

In the summer of 1987 a project was initiated to study certain aspects of the environmental impact of tunnelling for the Channel Tunnel. The study areas were situated in East Kent between Dover and Folkestone. At one of the chosen study sites, a male and female of the linyphiid spider Minicia marginella (Wider), hitherto unknown from Britain, were taken in pitfall traps. Both sexes of the species are described and illustrated from the British material.

Abbas, A.

doi: 10.1111/j.1469-7998.1991.tb06033.xpmid: N/A

The diet of coypu (Myocastor coypus) on two sites in a managed marsh was investigated by field observations and microscopic analysis of faeces. The habitat is mainly grazing pasture and over 51% of the plant fragments recovered from faeces were leaves of Graminaceae. Other food included hydrophytes, Cyperaceae, dicotyledons, flowers and seeds of Graminaceae and various roots. The mean annual diet of coypu was similar at both sites and showed moderate interannual variations. Relative proportions of different foods varied with season and availability. Hydrophytes, mostly Lemnaceae, were preferentially selected in late summer and autumn. Coypu fed on roots during winter, particularly in periods of exceptional food shortage due to flooding and severe frost. Even when crops were available, coypu utilized a wide range of food. The study shows the importance of feeding strategy in the ability of coypu to colonize new habitats, particularly those which are man‐made.

Beal, A. M.

doi: 10.1111/j.1469-7998.1991.tb06034.xpmid: N/A

Saliva was collected from the parotid glands of anaesthetized common wombats (Vombatus ursinus) to ascertain the maximal flow rates, salivary composition and possible adaptations to the diet. After temporary catheterization of the parotid duct through the oral opening, salivary secretion was evoked by ipsilateral intracarotid infusion of acetylcholine at varying rates to produce salivary flow rates ranging from 0.017±0.0012 ml.min‐1 (0.62±0.037 μmin‐1.kg‐1 body weight) to 2.00±0.148 ml.min‐1 (70.5±3.21 μl.min‐1kg‐1 body weight). The concentrations of Na (22.2±5.50 to 107.0±5.2 mmol.1‐1) and H+ (12.5±1.73 to 17.4±1.40 nmol‐1‐1) were positively correlated with salivary flow rate. The concentrations of K (99.3 ± 6.51 to 13.7±0.62 mmol.1‐1), Ca (1.36±0.229 to 0.74±0.021 mmol.1‐1), Mg (1.14±0.092 to 0.03±0.002 mmol.1‐1), HCO3 (65.3±2.43 to 55.7±1.70 mmol.1‐1), PO4 (3.30±0.334 to 0.51±0.038 mmol‐1‐1), protein (2.08±0.284 to 0.49±0.084 g.1‐), amylase activity (6.75±1.515 to 1.97±0.538 mkat.1‐1) and urea (10.9±0.89 to 3.88±0.28 mmol‐1‐1) were negatively correlated with flow rate. The relationships between salivary flow and C1 concentration or osmolality were diphasic: negative at low flows and positive at high flow rates. The patterns of excretion of the major anions in the saliva differed substantially from those reported for parotid glands of other marsupials. The saliva had levels of amylase activity which were far higher than those of other marsupials and which may be an adaptation to a diet rich in carbohydrate. Salivary Na/K ratios were not decreased by high‐rate intracarotid infusion of aldosterone (80–100 μg.h‐1 for 4 h) which indicated that the wombat gland, like the parotid glands of macropods, requires chronic exposoure to high levels of mineralocorticoides to sensitize the gland.

Cancicatti, C.; Quaglia, A.

doi: 10.1111/j.1469-7998.1991.tb06035.xpmid: N/A

The coelomic cavity of freshly collected Holothuria polii specimens contains a variable number of brown pigmented and unpigmented encapsulating structures. They are composed of nodules with entrapped parasites and an internodular mass which comprises a number of nodules. Both brown and unpigmented bodies occur in different size classes depending upon the number of nodules accumulated in a complete body. The unpigmented bodies probably represent an early unmelanized stage of the brown ones.

Roeleveld, Martina A. Compagnro; Lipinski, M. R.

doi: 10.1111/j.1469-7998.1991.tb06036.xpmid: N/A

Three specimens of the rare giant squid (genus Architeuthis, 18 nominal species) are described from the waters around southern Africa. Consideration of their internal and external morphology, including beaks, radula, statocyst and statolith give no reason to suppose that the three specimens do not pertain to the same species. A standardized data collection form and a summary of existing morphometric data are presented for the first time and the morphology and systematics of the genus are discussed. The value of various systematic characters is examined and certain guidelines are proposed, with an appeal for a more scientific approach to Architeuthis studies.

Whitear, M.; Zaccone, G.; Ricca, M. B.; Cascio, P. Lo

doi: 10.1111/j.1469-7998.1991.tb06037.xpmid: N/A

The venom glands of Heteropneustes lie deep in the epidermis at the sides of the pectoral fin spines, and consist of large cells that react positively to histochemical tests for proteins, histidine and tyrosine, negatively to periodic acid‐Schiff and for serotonin and bombesin. The venom cells are of two types, appearing to have dense or lucent cytoplasm when seen by electron microscopy. The dense type has the better developed Golgi systems, the lucent type has more ribosomes. Both appear to differentiate from the basal layer of the epidermis. The epidermis over the glands has a zone with relatively few desmosomes and enlarged intercellular spaces. Both staining reactions and fine structure differentiate the venom gland cells from the club cells of the epidermis, to such an extent that they must be considered distinct secretory elements.

Lefcort, H.; Blaustein, A. R.

doi: 10.1111/j.1469-7998.1991.tb06038.xpmid: N/A

Hamilton & Zuk (1982) hypothesized a positive correlation between a species' sexual showiness and its level of parasitic infection. We tested the hypothesis in 26 species of lizards, members of a class of vertebrates never before used to test the model. The prevalence of parasites was determined using published lists of parasites found in wild lizard populations. An index of showiness (brightness) was derived by scoring photographs of lizards in natural settings. Contrary to expectations of Hamilton & Zuk (1982), we found an inverse correlation between a lizard species' brightness and parasite prevalence. No correlation was found between a species' brightness and the number of parasite genera, species, or percentage of individual infecting parasite taxa. These results are discussed in relation to other interspecific tests of the hypothesis.

Hislop, J. R. G.; Harris, M. P.; Smith, J. G. M.

doi: 10.1111/j.1469-7998.1991.tb06039.xpmid: N/A

Wet and dry calorific values (energy densities) and total energy content of lesser sandeel Ammodytes marinus, sprat Sprattus sprattus, Atlantic herring Clupea harengus, whiting Merlangius merlangus, saithe Pollachius virens and cod Gadus morhua, were measured. Calorific values varied both within and between species. Larger fish tended to have higher calorific values than small ones, particularly when considered in terms of wet weight, but there was considerable temporal variation. The calorific values and body weights of sandeels larger than 10 cm showed marked seasonal trends and in consequence the total energy content of a sandeel of given length in summer is approximately double the spring value. The calorific values of herring and sprat also varied from month to month but seasonal cycles were less obvious. Whiting varied least. Both calorific values and total energy content of individual sprat were very variable in summer (the spawning season of this species). Because there is so much intraspecific variation, care must be taken when assessing the relative merits (in terms of energy) of different species as prey. The practical difficulties of obtaining reliable data on wet calorific values are discussed and the use of dry calorific values and dry weight/length relationships is recommended.