曼氏无针乌贼胚胎发育的初步观察

Preliminary observation on embryonic development of Sepiella maindroni

将曼氏无针乌贼受精卵卵膜剥离,在显微镜或解剖镜下观察胚胎发育的全过程,结合室内人工育苗的孵化技术进行探讨。曼氏无针乌贼卵为粘性卵,呈黑色,类型属端黄卵,卵膜属三级卵膜,卵裂类型为不全卵裂,囊胚呈盘状,发生类型为直接发生型。在水温为23.8～26.2℃、盐度29.3时,最快14d孵出幼体,最慢23天孵出幼体,孵出幼体高峰期为18～21d,高峰期的孵出量占总孵出量的79.4%,孵化率为83.1%。胚胎发育速度与温度高低(20～30℃)成正比,盐度低于22对孵化率有严重影响。

Combined with artificial breeding techniques of Sepiella maindroni, embryonic development of Sepiella maindroni was observed under microscope or anatomical lens by peeling off egg membrane of fertilized eggs. Egg of S. maindroni was anisolecithal and adhesive, and black in color. Its egg membrane was tertiary egg membrane; it showed meroblastic cleavage, and was discoblastula and directive occurrence type. The incubation period was from 14 d to 23 d at temperatures of 23.8-26.2℃, salinity 29.3, and the peak hatching time was 18-21 d. The hatching rate was 83.1%, accounting for 79.4 % of the whole amount of hatched larvae. The speed of embryonic development was positively connected with water temperature （20--30℃）, and the hatching rate greatly decreased when salinity was lower than 22.