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

It’s more advantageous in terms of thermodynamics, i.e. energy expenditure vs energy gain, to eat the stuff that there’s more of, that’s easier to find, that’s lower on the food chain.

Now you might reasonably ask, why not go even lower on the food chain and eat, say, plants? Answer is, plenty of animals do that. When there’s competition for a food source, you have one fewer ecological niche to fill so as to avoid this costly competition, ergo, eating animals. And in addition digesting plant matter is a massive energy expenditure.