首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
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   

2.
3.
4.
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, Australia2Present 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   

5.
6.
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   

7.
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   

8.
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   

9.
10.
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   

11.
12.
13.
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   

14.
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   

15.
Several aspects of the natural history of the sympatric busyconinewhelks Busycon contrarium and Busycotypus spiratum were examinedalong the northwest Gulf coast of Florida. Field and laboratoryobservations were made on feeding rate, crawling speed, sizedistributions, growth rate and reproduction. The two specieswere similar in several respects. Both were slow-growing withgrowth occurring only above 20°C. Modal sizes for both specieshave markedly declined over the past two decades. Feeding ratesand crawling speeds were affected by seasonal temperature changes,being highest at intermediate temperatures. Both species copulatein late autumn to early winter, lay egg capsules in early spring,with hatching beginning in May. One major interspecific difference was observed; the crawlingspeed of B. spiratum was twice that of B. contrarium. This differencewas correlated with the larger foot of B. spiratum. (Received 20 January 1982;  相似文献   

16.
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   

17.
18.
讨论了S.A.Rohwer记述的中国台湾叶蜂种类分类地位变化以及相关种类的异名关系.本文修订了3种,建立1个新异名和1个新组合,恢复1个有效种,并建立一个相关的新异名:Athlophorus melanocoxa Rohwer,1916,syn.nov.,被降为黑唇平背叶蜂Allantus luctifer(Smith,1874)的次异名;Athlophorus terminatus Rohwer,1916被移到前室叶蜂属Asiemphytus Takeuchi内,构成新组合:Asiemphytus terminatus (Rohwer,1911),comb.nov..白唇侧齿叶蜂Neostromboceros leucopoda Rohwer,1916从Pseudostromboceros atratus(Enslin,1911)的异名中移出,恢复为有效种,同时将Neostromboceros tonkinensis Forsius,1931,syn.nov.,降为Neostromboceros leucopoda Rohwer的次异名.  相似文献   

19.
Three new species of Anadyomene are described. Anadyomene lacerata has pinnately branched veins and a unique lacerated margin formed by elongated vein cells. Anadyomene linkiana consists of a perforate blade arising by polychotomous branching from a distinct stripe, and A. howei has an eperforate, delicate blade of polychotomously branched cells and a smooth margin of elongated vein cells. Distinguishing features of the five previously described species are clarified, and all eight taxa are illustrated. Observations in the field and from more than 400 herbarium specimens form the basis for a discussion of Indo-Pacific affinities, ecological adaptations, cell division, reproduction, and ordinal status. A phylogenetic analysis based on 17 equally weighted characters produced a cladistic gradation, indicating that Anadyomene is a monophyletic genus. The most basal species (A. saldanhae, A. linkiana, A. howei, A. menziesii) show only polychotomous branching. In contrast, the distal group (A. pavonina, A. stellata, A. rhizoidifera, A. lacerata) have pinnate interstitial cells along the veins in addition to polychotomous branching at the vein apices.  相似文献   

20.
The esterase system has been studied using isoelectric focusingin two closely related rough periwinkles, Littorina saxatilisand L. arcana, in an investigation of possible differences betweenthe two species at this level of discrimination. Collectionsof both species were obtained from Yorkshire, north Cornwalland south Devon; L. saxatilis was also obtained from sites insouth Cornwall (in and near the estuary of the Tamar), Dorsetand Scotland, where L. arcana was not present. There is considerablevariation both within and between sites which tends to maskany overall differences between the two species. However, ingeneral there is a much greater degree of heterogeneity withinsamples of L. saxatilis than within samples of L: arcana whenboth species are found together; this is reflected in the ShannonWiener diversity index for bands. Also the number of esterasebands is greater for L. saxatilis than for L. arcana at eachof the five sites where both occurred. A dendrogram derivedfrom the percentage occurrence of each band present in eachsample produced a reasonable degree of separation of the twospecies (Received 8 January 1988; accepted 24 February 1988)  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号