Question

read the second part of the passage about blue whales.
blue whales are big, but they eat tiny sea animals. the sea animals they eat are called krill.
blue whales open their mouths when they swim. that way, they can get a lot of krill at once.
complete the sentence.
blue whales eat __________.
sea birds small sea animals other whales

Explanation:

The passage clearly states "Blue whales are big, but they eat tiny sea animals. The sea animals they eat are called krill." Krill are small sea animals.

Answer:

small sea animals