opisthonephros

例句：

1. 1.The opisthonephros is a rare and endangered species.
   无鳍鱼是一种罕见的濒危物种。
2. 2. The opisthonephros plays an important role in the ecosystem.
   无鳍鱼在生态系统中扮演着重要的角色。
3. 3. The discovery of the opisthonephros has sparked a new interest in marine biology.
   发现无鳍鱼引起了对海洋生物学的新兴趣。