扁平圆扁螺(Hippeutis complanatus)早期发育的形态观察

Morphological Observation of the Early Developmental Stages of Hippeutis complanatus

在水温18℃左右条件下培养扁平圆扁螺(Hippeutis complanatus),使其产卵,在光镜下观察其早期发育过程,详细描述各发育阶段的形态特征.扁平圆扁螺胚胎发育属典型的包囊幼虫发育类型,其过程共分为6个时期,即卵裂期、囊胚期、原肠期、担轮幼虫期、面盘幼虫期和仔螺形成期.胚胎于面盘幼虫晚期孵化,在水中完成仔螺形成过程,腹足从三角变为长楔形,幼虫肾退化,螺壳平伏形成仔螺.

Hippeutis complanatus was cultured in the laboratory at 18 ℃ until spawning. Early development of H. complanatus was studied by using light microscope. Morphological characteristics of each developmen- tal stage were described in detail. Early development of H. complanatus was a typical type of cyst larvae and could be divided into six stages： cleavage, blastula, gastrulae, trochophora, veliger, and formation of young snail. H. complanatus hatched at late veliger stage, and finished the process of formation of young snail in the water. During the process, gastropod of the young snail changed from triangular shape into long-wedge shape, larvae renal of the young snail died away and shell of the young snail became flat.