Platyelminthes

例句：

1. 1. The platyelminths are a group of flatworms that live in the ocean.
   扁形动物是一类生活在海洋中的扁平动物。
2. 2. Platyelminths are found in many different environments, including freshwater and marine habitats.
   扁形动物存在于多种环境中，包括淡水和海洋栖息地。
3. 3. In recent years, scientists have discovered new species of platyelminths in the Arctic region.
   近年来，科学家在北极地区发现了新的扁形动物物种。