aquatic mammal

例句：

1. 1. Many species of marine mammals are found in the oceans.
   许多海洋哺乳动物在海洋中被发现。
2. 2. The whale is an aquatic mammal that feeds on fish and squid.
   鲸鱼是一种水生哺乳动物，以鱼类和鱿鱼为食。
3. 3. Aquatic mammals play an important role in maintaining the balance of ecosystems.
   水生哺乳动物在维持生态系统平衡方面起着重要作用。