Krill are eaten by whales, penguins, seals, squid, fish and people. Although krill are also eaten by hundreds of other animals, these are their greatest predators. Whales eat the larges amount of krill; the blue whale can eat up to four tons of krill each day. The diet of Adelie penguins mainly consists of krill, although all 17 species of penguin depend on krill to survive.