桡足类大颚齿缘与摄食机制关系的研究

STUDY ON THE RELATIONSHIP BETWEEN MANDIBULAR EDGE AND FEEDING MECHANISM OF COPEPODA

扫描电镜(SEM)观察结果揭示了13种常见桡足类大颚齿缘的形态特征,表明食性不同的种类在齿式、齿数及齿形等方面有明显差异,并发现同一食性的种类具有两种不同的颚齿构造,因而推测它们有着不同的咀嚼机制。SEM图片还揭示了一些在光镜下无法看到的细微结构,如小孔及刺毛等。这些细微结构的发现有助于当前关于桡足类摄食机制的讨论。此外,计算结果证实了肉食性种类的齿缘指数(EI)远大于草食性桡足类;但介于二者之间的杂食性类群,其EI值变动幅度大于Itoh指定的范围。

The photographs obtained by SEM show the complex three-dimensional structure of man-dibular edge of thirteen common copepods occurring in Jiulong River Estuary and its vicinity. The present investigation reveals the difference among the separate feeding patterns in edge model, number and shape of teeth, and shows that there are two kinds of edge shape in the-same feeding patterns. The photos also show structural details which cannot be observed under the optical microscope. The results reveal that most of species have microsetae at the basal-part of teeth. In addition, a kind of small pore is found on the edge of some species. All these microstructure may be related to the receptors of mandibles. The calculation of 'edge index', (EI) from the SEM photos shows that in these copepods, EI values conficm to a tendency of increasing with predacity. But the El value of omniverous copepods tends to have more variable range than that stated by Itoh.