对条斑星鲽仔、稚鱼发育形态异常的观察

The observation of abnormal morphological characters of Verasper moseri larvae and juvenile

对条斑星鲽(Verasper moseri)仔、稚鱼发育过程中正常和畸形个体的形态进行了观察。结果表明,条斑星鲽仔稚鱼形态异常出现于孵化后第5天,第7天和第8天表现最为明显。仔、稚鱼可分为3种类型:异常类型A:鳃盖和下颌骨发育不良,口膜不通、口不能自由闭合,腹部膨大,胸鳍没有发育,漂浮于水面;异常类型B:鳃盖、下颌骨发育不全,口闭合不全。胸鳍发育不良,漂浮于水面,偶尔水平运动;正常类型C:鳃盖、下颌骨发育正常,口能自由闭合,胸鳍明显变大,靠尾的摆动和胸鳍的快速划动在水中水平游动。A、B类型在孵化后第15～20天大量死亡,B类型少部分个体可以少量摄食并继续发育,但是生长速度缓慢,不能完成变态,发育到第30～50d天时死亡。正常发育个体孵化后第30天d左眼开始上移,第50天大部分左眼完全移至右侧,褪色、着底。色素异常观察发现,褪色着底时,近10%个体出现白化现象,几乎没有形成成体色素。

The morphological characters of normal and abnormal individuals were observed during the development period of larva and juveniles. The abnormal morphological characters of Yerasper moseri larva and juveniles appear firstly on the 5th day after hatching and exhibit clearly on the 7th-8th day after hatching. The morphological characters have three types. Abnormal type A： Larva has not well developed operculum and mandible bone so mouth could not shut and mouth has not been transfixed, abdomens swell, pectoral fins have not developed, larvae could only float on water surface; Abnormal type B： Larva has abnormal operculum and mandible bone, so mouth could not shut fully, and pectoral fins do not develop well, so larva could only float on water surface and swim once in a while; Normal type C： Larva has normal operculum and mandible bone, so mouth could shut freely, and pectoral fins develop well, so larvae could swim horizontally by swing of caudal fins and quick rowing of pectoral fins. Most larva of abnormal type A and B die on 15th-20th day after hatching. Some larva of type B can feed a little and develop, but they grow slowly, could not accomplish metamorphosis development, and die on the 30th-50th day after hatching. For normal larva, left eyes of larva begin to move upwards on the 30th day after hatching, and move to right side completely on the 50th day. At this time, the larva depigmentizes and lands on bottom of tank. Abnormal body color： after depigmentizing, about 10 percents of larva could not form adult melanophores and show albinism.