What happens to unusable energy in a food web?

that animals with start getting extinct

bacteria feeds on the unusable energy in a food web which creates a productive ecosystem

Explanation:

for example when a whale dies it falls to the ocean flour than other animals feed on it that when the bacteria feeds on the carces it resycles the unusable energy

option c is the correct answer.

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.