Alcyonacea

例句：

1. 1.The Alcyonacea is a group of marine animals that are known for their unique venomous tentacles.
   水母亚纲是一种以它们独特的毒刺而闻名的海洋动物群。
2. 2.In the Alcyonacea, there are many species that can change color to blend in with their environment.
   在水母亚纲中，有许多物种能够改变颜色以适应其环境。
3. 3. The Alcyonacea plays an important role in the ecosystem by filtering and removing pollutants from the water.
   水母亚纲在生态系统中起着重要的作用，通过过滤和去除水中的污染物。