Tylenchida

例句：

1. 1. Tylenchida are fascinating creatures that live in water.
   水螅是一种令人着迷的生物，它们生活在水里。
2. 2. The Tylenchida were once common in the oceans, but now they are endangered.
   水螅曾经是海洋中的常见生物，但现在它们濒临灭绝。
3. 3. Scientists have been studying Tylenchida for decades to understand their behavior and evolution.
   科学家已经研究了几十年来了解水螅的行为和进化。