婆罗囊螺早期发育的初步研究

Preliminary Study on the Early Development of Retusa borneensis

描述了婆罗囊螺 (Retusaborneensis)从受精卵到幼虫孵化后的发育过程 ,婆罗囊螺为雌雄同体的一年生贝类 ,在浙江沿海繁殖期是 6～ 9月 ,盛期在 7～ 8月。婆罗囊螺为体内受精种类 ,胚胎发育过程为变态发育 ,可以分为卵裂、囊胚、原肠胚、担轮幼虫和面盘幼虫等几个阶段。个体发育从受精卵的卵裂开始 ,卵裂为螺旋形的全裂。卵裂不断进行 ,囊胚形成 ,后以外包和内陷方式共同形成了原肠胚。婆罗囊螺的面盘幼虫在膜内就已经形成 ,并且具备运动能力 ,但是其面盘和纤毛远没有膜外面盘幼虫发达。幼虫浮游一段时间后 ,就营匍匐生活 ,然后变态发育为稚贝。本文还就婆罗囊螺的繁殖期、繁殖力、交配产卵和繁殖特性等做了进一步的讨论。

The development of Retusa borneensis, from fertilized egg to juvenile is described. Retusa borneensis is monoecism and annotinous. Its spawning period in the Zhejiang coast eastern China Sea is from June to September, and the its peak reproductive period is from July to August. The R. borneensis performs internal fertilization. Metamorphosis is necessary during the development courses, which can be divided artificially into cleavage, blastula, gastrula, trochophora, creeping larva veliger and juvenile stages. Cleavage is spiral and holoblastic, and results in the formation of blastula. Gastrulation occurs partly by epiboly and partly by invagination. The veliger form is assumed within the egg membrane,which can move automatically .The velar and cilia are comparatively less well developed than that of planktonic veligers. Planktonic veligers creep for several days, and then become the juvenile R. borneensis after the metamorphosis period. Besides, the reproductive period, the mating and spawning, the features of reproduction were discussed in this article.