黄鳍金枪鱼仔鱼脊柱及附肢骨骼的发育

Development of vertebral column and appendicular skeleton in larvae of Thunnus albacares

摘要:

为了探明黄鳍金枪鱼（Thunnus albacares）脊柱及附肢骨骼的发育特征,基于2022年8月15日—9月9日在菲律宾海用大型仔稚鱼网（口径1.3 m、网目0.5 mm）进行表层水平拖网所采集的黄鳍金枪鱼仔鱼样本,采用软骨-硬骨双染色透明技术,观察了黄鳍金枪鱼仔鱼（前弯曲期9尾,弯曲期12尾,后弯曲期12尾,体长3.1~8.0 mm）脊柱及附肢骨骼的早期发育。结果显示,各鳍形成顺序是胸鳍、尾鳍、第一背鳍和腹鳍、第二背鳍和臀鳍,最后为小鳍；椎体由体前部向尾部逐渐形成；髓弓由体前部向尾部和由体中部向两端生长,脉弓由体中部向两端生长；尾下骨1和2先愈合为一个整体,随后侧尾下骨和尾下骨1+2的基部软骨联合,尾下骨3和4两端愈合,尾下骨5独立；体长8.0 mm个体形成躯椎18枚,尾椎21枚,侧尾下骨1枚,尾下骨5枚,尾上骨2枚。研究表明,侧尾下骨和尾下骨愈合为黄鳍金枪鱼提供了强劲的游泳动力。本研究可作为黄鳍金枪鱼早期阶段的鉴定依据,并为其仔鱼阶段的漂流机制形成提供参考。

关键词:黄鳍金枪鱼;骨骼发育;脊柱;附肢骨骼;软骨-硬骨双染色透明技术

Abstract:

To understand its osteological development during early stage, 33 larval specimens of Thunnus albacares （9 preflexion larvae, 12 flexion larvae, 12 postflexion larvae, body length： 3.1-8.0 mm） were collected by horizontal trawling at the surface layer by a larval net （1.3 m in diameter, 0.5 mm in mesh size） in the Philippine Sea from August 15th to September 9th, 2022. The specimens were stained and cleared for both cartilage and bone to evaluate their vertebral column and appendicular skeleton development in T. albacares. The results show that the fins were developed in following sequence： pectoral fin, caudle fin, the first dorsal fin and pelvic fin, the second dorsal and anal fin, and finally, finlets. Centrum was formed in a posterior direction. Neural arches were formed in a posterior direction at anterior part of the body and in both anterior and posterior at the middle part of the body. Haemal arches proceeded both anteriorly and posteriorly. Hypural 1 and 2 were fused, and then jointed with the parhypural by cartilage. Hypural 3 and 4 were fused at both ends. Hypural 5 was dissociated. There are 18 precaudal vertebrates, 21 caudal vertebrates, 1 parhypural, 5 hypurals and 2 erpurals in 8.0 mm specimen. The fusions of parhypural and hypurals could enhance the swimming ability for T. albacares. This study can be used as a basis for the fish identification and provides an evidence for the formation of the drift mechanism of T. ablacares larvae.

Key words:Thunnus albacares;osteological development;vertebral column;appendicular skeleton;staining and clearing technique of cartilage and bone