南极海域富含磷虾，它们是鲸鱼的主要食物。

The Antarctic waters are rich in ___krill, which are the primary food for whales.

鲸鱼以大量的磷虾为食，这些磷虾群是海洋生态系统的重要组成部分。

Whales feed on massive swarms of ___krill, which are vital to the ocean ecosystem.