How do crocodiles breathe underwater?
They don’t breathe if they are completely underwater. Their nostrils are on top of their snout and act as a snorkel when they are floating at or just below the surface, but underwater they hold their breath. Because they are reptiles and cold blooded, they have much slower metabolisms and they do not create excess energy. Basically, if there’s nothing to do, they do nothing. Because they are so sedentary, they use less oxygen, so they are able to hold their breath longer. Stationary muscles require less oxygen than moving muscles. That’s why you breathe harder after a run.
