圆斑星鲽胚胎及仔鱼发育的观察

Embryonic and larval development in Verasper variegatus

对圆斑星鲽(VeraspervariegatusTemmincketSchlegel)胚胎及胚后发育进行观察,描述了各发育时期的形态特征和发育速度。在水温为(11±0.5)℃时,受精卵历时153h脱膜孵出,孵化后仔鱼在水温为(15±0.5)℃时经过6d开口摄食,50d完成变态而成幼鱼。圆斑星鲽的卵子为半浮性卵,其卵黄量很多。卵裂后期,卵裂球的大小和卵裂速度均出现差异。眼泡在体节形成之前出现。刚孵化仔鱼消化道细而直,孵化5d肛门打通,6d开口。随着卵黄囊的消失,消化道开始弯曲。色素细胞首先出现在86h的胚体中,至140h在卵黄囊上零星分布,且随着胚体发育,色素细胞增多,至变态完成后全身密布黑色色斑。胚体色素细胞的形状由孵化前的雪花状逐渐变为圆形,但卵黄囊上的色素细胞始终为雪花状。

The fertilized eggs of Verasper variegatuse were obtained by artificial conduction and the incubation conditions were: water temperature(11±0.5)℃, salinity 29-30, pH 8.2, and flowing water with continuously aerating. The larvae hatched out at about 153 h after fertilization and the larval mouths opened at 6th day and metamorphosis completed at about 50th day after the hatching. The laid eggs are halffloated with a large number of yolk. The blastomere size and the cleavage speed became different distinctly at the late cleavage. The formation of optic vesicle is earlier than somite. The guts are thin, short and straight in the newly hatched larvae, and then become longer and flexible during the larval development. The melanophores occurred in the embryo 86 h after fertilization in dispersal, and on the surface of yolk sac 140 h after fertilization, and distributed in all of the body after metamorphosis.The shape of melanophore existed on the body changes gradually from snowflakelike (before hatching) to spot shape (10 d after hatching), whereas those on yolk sac are snowflake shape all the time.