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1.
Aspects of the physiology and feeding behaviour of the scavengingsnails, Babylonia lutosa and Nassarius festivus have been studiedand compared. N. festivus has a wider physiological tolerancethan B. lutosa; upper lethal temperatures being 31.5°C and28.5°C respectively and lower lethal salinities 15.5 and11.5. N. festivus was also more resistant to desiccation. N.festivus is adapted to an intertidal environment that is morevariable than the subtidal habitat of B. lutosa. The metabolicrate of adult N. festivus was two to three times higher thanthat of adult B. lutosa, the specific oxygen consumption rateof the former being 7.91±0.49x10–6 mol of O2.g–1wet wt.hr–1. This correlates with estimates of consumptionobtained for the two animals, B. lutosa eating, on average,6.57% of its wet tissue weight per day, N. festivus 15.33%.Standardization of the data for 2 g animals of both species,however, reveals no significant difference in terms of oxygenconsumption and thus the enhanced consumption by N. festivussimply reflects its smaller size. Both species are opportunisticfeeders and can survive long periods of starvation (>100days). The feeding strategies of the two are also different,N. festivus eating faster than B. lutosa, possibly because ofthe more ephemeral nature of carrion in the intertidal. Starvationaffected the feeding behaviour of N. festivus more than B. lutosaand N. festivus was able to perceive carrion from greater relativedistances than B. lutosa. (Received 27 February 1989; accepted 24 July 1989)  相似文献   

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The intertimdal gastropod Thais malayensis n.sp. (Neogastropoda,Muncidae) is described from Singapore and peninsular Malaysia.Although a common species, it may have been previously overlookedor mistaken for other species found in and near mangroves. Anotherpoorly known species, T javanica (Phdippi) may also have beenconfounded with the new species. New data on their soft parts,radulae, opercula, and egg capsule morphology are presentedto distinguish between these closely related species. (Received 26 February 1996; accepted 15 May 1996)  相似文献   

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Lepsiella vinosa\ (Lamarck), a common intertidal predatory gastropod,was studied in two zones on an exposed rocky shore in Victoria(Australia). Those from the Mussel Zone in the mid-shore primarilyate one species of mussel and had a faster rate of energy consumptionthan those from the Littorinid Zone in the high-shore, whichmainly ate one species of littorinid gastropod. Shell length,growth rate and size-specific body weight of L. vinosa wereall significantly greater in the Mussel Zone. Egg capsules ofL. vinosa from the Mussel Zone contained significantly moreeggs and more potential hatchlings per capsule than those fromthe Littorinid Zone although there were no significant differencesin the sizes of eggs or hatchlings between zones. These differencesbetween the two zones were correlated to the greater consumptionof energy by L. vinosa in the Mussel Zone and were discussedin relation to the absence of dispersive larvae in this species 1Present address: Department of Zoology, Monash University,Clayton, Victoria, 3168, Australia 2Present address: School of Biological Sciences, Carslaw Building,F07, University of Sydney, N.S.W., 2006, Australia. Addresseefor reprints. (Received 2 June 1987;  相似文献   

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The effects of a population of the boring gastropod Natica tectaon the bivalve Choromytilus meridionalis were investigated atBailey's Cottage, False Bay, South Africa. In July 1979 theN. tecta density on the mussel bed averaged 69 m–2 andthe population consisted mainly of reproductively mature individualsbetween 20–33 mm shell width. Laboratory experiments on N. tecta showed that prey size selectionis an increasing function of predator size. The prey size rangetaken by large N. tecta is also greater than that taken by smallindividuals. The position of the borehole on the mussel shellis a function of the way in which the shell is held by the footduring the boring process. Consumption rates measured in thelaboratory showed an increase from approximately 1 kJ per weekin 18 mm N. tecta to 4.5 kJ per week in 28 mm individuals. Populationconsumption in the field was calculated as 663 kJ m–2month–1. It was estimated that at this rate the standingcrop of mussels in the pool would be eliminated within 10 months.Field measurements showed significant depletion after 6 months. New spat settlement of mussels occur every 4–6 years.The growth curve shows that after one year the population meansize exceeds 30 mm shell length, which is beyond the prey selectionsize range of small N. tecta. It was concluded that at the timeof a new mussel settlement a niche is provided for the simultaneoussettlement and growth of juvenile N. tecta in high densities.However, within one year the increase in prey size, togetherwith depletion due to over-exploitation, limits population growthand density in N. tecta. (Received 14 March 1980;  相似文献   

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本文研究并发现了新型半天然钙调素(CaM)拮抗剂--O-4-乙氧基丁基小檗胺(O-4-ethoxy-butyl-berbamine,EBB),具有选择性抑制肺巨细胞癌(PG)的增殖和降低细胞内CaM水平的能力,对人胚肺细胞(HEL)的增殖和细胞内CaM的水平影响较小.同时观察到EBB引起肿瘤细胞内CaM水平降低的原因,是对CaM基因的转录产物(mRNA)和翻译产物(CaM)两方面作用的结果.此外,EBB还能部分降低PG细胞内原癌基因和突变的抑癌基因转录产物mRNA的水平.EBB抑制肿瘤细胞增殖的机制,除了对CaM基因的表达水平和CaM活性调控外,可能还直接或间接地影响了相关的原癌基因和突变的抑癌基因的表达.  相似文献   

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Chlorella saccharophila (Krüger) Nadson takes up mannitol and sorbitol in the light and the dark. The rate of uptake is concentration dependent. is not affected by pH in the range pH 6.0 to 8.0 and ii not stimulated by light. Uptake is inhibited by the respiration inhibitor sodium azide (10-2 M) but not by 3-(3,4-dichlorophenyl)-1,1-di-methyl urea (10-6 M), an inhibitor of photosynthesis. Sorbitol. but not mannitol, stimulates the rate of dark respiration but both support the heterotrophic growth of the alga. Both compounds permeate the cells of C. miniata. and two strains of C. pyrenoidosa but do not support the heterotrophic growth of these algae. The cells of C. vulgaris are impermeable to both compounds.  相似文献   

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On sheltered rocky beaches in Hong Kong, Linatella caudata preysupon the lower-littoral and sub-littoral fringe fauna. Ascidiantests are cut with the radula, while the proboscis is insertedbetween the parted shell valves of bivalves. The salivary glandssecrete sulphuric acid that is not used in prey penetration,as in the Cassidae, but is more likely used in digestion ordefence. In preference experiments, prey were chosen in the sequence:Barbatia virescens (Bivalvia: Arcidae) > Styela plicata (Ascidiacea)/Saccostreacucullata (Bivalvia: Ostreidae) > Lunella coronata (Gastropoda:Turbinidae) > Balanus amphitrite (Crustacea: Cirripedia).52% of all attacks were upon Barbatia Lunella and Balanus wereattacked rarely. Prey preferences by individual gastropods werealso demonstrated. Calibration plots of total weight against wet and dry tissueweight of prey (Barbatia virescens) and, finally, the predatorwere obtained and used in estimations of consumption. On average,an adult Linatella caudata (10-15g) consumed three B. virescens.week–1 The mean weight of B. virescens flesh consumed.week–1 ranged between 0. 208–0.412g dry weight prey.gdry weight predator–1, i.e., a mean of 28.2% of the predator'body weight.week–1 or 4%.day–1. Such a figure accordswell with estimates of consumption obtained for other adultpredatory gastropods from Hong Kong. (Received 4 September 1989; accepted 5 December 1989)  相似文献   

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The pistillate inflorescence of Casuarina verticillata is described as consisting of a primary axis bearing whorls of bracts with a cymule in the axil of each bract of the more central whorls. Each cymule consists of an atepallate, two-carpellate, syncarpous floret and two, lateral, once-lobed bracteoles. A “peripheral intercalary” meristem, in which divisions are primarily periclinal, forms a meshwork beneath the bracts from early development and moves the connate bracts centrifugally around the cymules and extends and binds the bracts, and to some extent the bracteoles, of the fertile part of the inflorescence together. Each bract receives a single trace; each cymule receives two traces. Each bundle extension of a cymule trace supplies: 1) a branch which joins its counterpart to become the anterior common carpellary bundle; 2) a second branch which joins its counterpart to become the posterior common carpellary bundle; and 3) a central branch which supplies a lateral bracteole. Within each floret, each common carpellary bundle provides a dorsal carpellary bundle, two ventral carpellary bundles (fertile anterior carpel) or one common ventral bundle (sterile posterior carpel). The ventral bundle-supplies join and form a single placental bundle which lies in the gynoecial septum, and which, in turn, supplies the two ovules in the anterior carpel. Whether the inflorescence is a simple racemose or a condensed cymose type cannot be determined from this species alone. The function of the sclerenchymatous, enclosing bracteoles and connate bracts is discussed.  相似文献   

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The morphology of some deep-sea Turridae lacking radulae wasstudied. The main features of their digestive system are theabsence of a radula sac, venom and salivary glands and the reductionor absence of a proboscis. A new genus Teretiopsis including3 new species and T. thaumastopsis (Dautzenberg and Fischer,1896) is described. On the basis of differences of the digestivesystem when compared with other turrids lacking radulae themonotypical subfamily Taraninae Casey, 1904 new status (typegenus Taranis Jeffreys, 1870) is considered. It is shown thatthe process of radula reduction has occurred independently indifferent phylogenetic lines of Toxoglossa—the subfamiliesDaphnellinae and Taraninae among Turridae and the family Terebridae. (Received 8 August 1988; accepted 20 December 1988)  相似文献   

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温度和盐度对缢蛏浮游幼虫发育的影响   总被引:15,自引:1,他引:14  
林笔水  吴天明 《生态学报》1984,4(4):385-392
本文叙述了在室内控制条件下,温度和盐度单因子及其结合对缢蛏浮游幼虫的影响。缢蛏浮游幼虫生长发育的适温范围为17°—32℃,其中以25°—27℃为最好。对高温和低温有较强的耐力,致死温度的上限为40℃左右,变态的下限水温为15℃左右,幼虫适盐范围是4.50—28.30‰,其中以12.40‰为最适宜,但幼虫对低盐度的耐力比对较高盐度的耐力强。 温度对缢蛏浮游幼虫期的长短、增长速度和存活率的影响,要比盐度对它的影响显著,而盐度对缢蛏幼虫变态率的影响却比温度重要些。温度与盐度对缢蛏浮游幼虫发育影响的相关性不明显。  相似文献   

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笔者在整理浙江沿海荔枝螺属Thais Roeding,1798标本时,经形态分类方法和分子生物学方法鉴定发现1新种,即大渔荔枝螺Thais(Stramonita)dayunensis sp.nov.,隶属于腹足纲、前鳃亚纲、新腹足目、骨螺科、红螺亚科、荔枝螺属、Stramonita亚属.文中对新种的形态特征和栖息环境进行了记述,并与近似种进行了比较讨论.  相似文献   

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‘小黑瓢虫Delphastus cataline(Hom)是我国1996年引进的粉虱重要捕食性天敌.引进后我们对其进行保种定殖,并研究了其对甘薯粉虱Bemisia tabaci的捕食选择性和种内干扰反应.  相似文献   

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Shell variation in two species of the tropical freshwater snailBellamya from two different habitats, was studied. The variation of the shell features studied, which includedthe shell width, spire height, aperture height and aperturewidth, were found to be related to shell height. Furthermore,significant difference in the shell shape was found not onlybetween the two species but also between males and females ofeach species. (Received 18 August 1983;  相似文献   

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蝇类在世界各地的分布极为广泛,种类繁多,每年出现季节较长,与人群接触极为频繁,因而常为传染各病的媒介,在我国已往对蝇类的分布及其与传染病的关系,所作的调查研究并不太多。姚、袁等氏(1929)在北京调查结果,发现在多数蝇类的体内含有大肠杆菌,且自肠内分离出痢疾杆菌,以及结肠内阿米巴、赤痢内阿米巴包囊,及鞭毛虫,纤  相似文献   

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