在实验室条件下孵化脉红螺的卵囊,观察其胚胎和浮游幼体发育过程,及脉红螺早期发育过程的形态学变化。卵囊在25 ℃时孵化时间为16 d,经过卵裂期、囊胚 期、原肠胚期、膜内担轮幼虫期,最后发育为膜内面盘幼虫,破膜而出开始浮游幼体发育阶段。脉红螺浮游幼体期按螺层、面盘形态、幼体壳型和器官可分为5个 时期,分别为1螺层期;2螺层期(初期、中期、后期);3螺层期初期;3螺层中后期;4螺层期(初期、中期、后期)。其中在2螺层后期幼体的生长速度最快,壳高平均 每天增加44.45 μm,3螺层初期幼体的生长速度最慢,壳高平均每天增加19.51 μm。脉红螺附着变态的时期是4螺层中期和后期,壳高1 250～1 500 μm,附着变 态的标志是浮游幼体壳口边缘明显加厚并向壳口外侧翻转,壳口中央突起部消失,面盘退化,足部发达并能自由伸缩。

Embryos and larvae of the prosobranch gastropod mollusk Rapana venosa were artificially incubated and hatched from egg masses under laboratory conditions,and morphological changes during the early development were observed.Fertilized eggs developed into veligers in about 16 days at temperature 25 ℃.Embryonic development included six stages:cleavage,blastula,gastrulae,trochophore in egg membrane,intra-membrane veliger,and veliger.The planktonic larval development was divided into five stages,including one-spiral whorl stage,two-spiral whorls stage(early,mid and late),early three-spiral whorls stage,mid and late three-spiral whorls stage,four-spiral whorls stage(early,mid and late).The highest growth rate of larvae was observed during the late two-spiral whorls stage with an increase of 44.45 μm in shell height per day,while the lowest was in early three-spiral whorls stage with an increase of 19.51 μm in shell height per day.The settlement and metamorphosis of veligers occurred in the mid-to-late four-spiral whorls stage with the shell height of 1 250-1 500 μm.Morphological changes during the settlement and metamorphosis of veligers could be summed up as:incrassation of edge of shell aperture,exstrophy of shell aperture,disappearance in the middle edge of shell aperture,degeneration of velum of veligers,and the broadened feet which could flex freely.

国家“十二五”科技支撑计划课题(2011BAD13B01,2011BAD45B01);国家自然科学基金项目(31200280)