这两个纲的许多种类都有水母型和水螅型的世代交替。

The two key link in many types of jellyfish are generational-type and Hydra type.

youdao

其实珊瑚一词所指的动物甚多，包括大多数属珊瑚虫纲及数动属水螅虫纲的刺胞动物。

Actually, the term coral is much broader and refers to most of the animals in the class Hydrozoa of the Phylum Cnidaria.

youdao

其实珊瑚一词所指的动物甚多，包括大多数属珊瑚虫纲及数动属水螅虫纲的刺胞动物。

Actually, the term coral is much broader and refers to most of the animals in the class Hydrozoa of the Phylum Cnidaria.

youdao