Why do whales eat a huge amount of small fishes instead of a few large ones?

Question

I remember watching a documentary once and learned that whales need to eat tonnes (literally) of krill per day to survive. I don’t understand why this is better than eating small amounts of large fishes instead.

In: 298

Answer 1

Same reason your car doesn’t run on rocket fuel.

I think you’re trying to imply that because something sounds easier, evolutionarily it should be chosen? Or why God created whales that way? Either way, it’s leading the question and borderline against ELI5 rules.

They eat small fish because that’s what their body can do. Why doesn’t a lion just bite into a tree? Less energy chasing it!