红眼寄居蟹在实验室和野外条件下对贝壳的利用

占据适宜的贝壳对于寄居蟹的发育、繁殖和存活至关重要。尽管很多研究探讨了蟹类对贝壳的选择,但寄居蟹选择多大的贝壳仍不清楚。在实验条件下,本文作者用巴西Anchieta岛上野生红眼寄居蟹( Pagurusbrevidactylus)最常利用的黑衣蟹守螺( Cerithium atratum)和节桑椹螺( Morula nodulosa)进行了贝壳选择实验,通过回归分析确定目标贝类及其大小。观察到寄居蟹对一种独特贝类的选择具有性别意义,从而验证了野外观察结果。雄性明显地倾向选择黑衣蟹守螺的贝壳,而产卵和非产卵的雌性个体对腹足类贝壳的选择差异不显著。尽管两性之间对适宜贝壳的选择存在差异,贝壳适宜度指数(SAI)表明,种群占据那些足够大的贝壳(SAI =1·20±0·23)。红眼寄居蟹对贝壳利用的这种模式可能是为了避免与体型相似同域物种的竞争,从而在后来的生长中减少频繁地更换贝壳。根据目前的数据可以得到以下结论:红眼寄居蟹对贝壳的选择不仅取决于贝壳的参数,而且还与寄居蟹的个体和性选择有关动物学报51 (5) : 813 -820 , 2005]。

Shell use by the Pagurus brevidactylus(Anomura,Paguridae):a comparison between laboratory and field conditions

The occupancy of suitable shells is essential to the development,reproduction and survivor of the hermit crabs.Although many studies have explored shell selection worldwide,the parameters by which a particular shell is chosen by a hermit crab are not completely known.Experiments of shell selection were conducted under laboratory conditions,utilizing the two most occupied shell species,dark cerith Cerithium atratum and blackberry drupe Morula nodulosa,at natural habitat by Pagurus brevidactylus from Anchieta Island,Brazil.The preferred shell species and size were determined by regression analysis.A distinct shell species preference was observed as a function of hermit crab sex,corroborating field observations.Males preferred significantly Cerithium atratum shells,while ovigerous and non-ovigerous females showed no significant choice among the gastropod shells tested.Despite such difference both sexes selected suitable shells.The shell adequacy index(SAI)showed that the population was occupying shells larger than the adequate size(SAI=1.20±0.23).This pattern of shell utilization by P.brevidactylus may be to avoid competition with sympatric species with similar body sizes and to allow future growth without the need of changing shells very often.The present data lead us to conclude that shell selection by P.brevidactylus depends not only on parameters of the shell but also on crab individual and sexual preferences