Question

Why can whales not breathe underwater?

Answer 1

Whales cannot breathe underwater because they lack gills. They use their blowholes, which needs to be above the surface of the water to draw in air.

Answer 2

Whales and dolphins are mammals and breathe air into their lungs, just like we do. They cannot breathe underwater like fish can as they do not have gills. ... After each breath, the blowhole is sealed tightly by strong muscles that surround it, so that water cannot get into the whale or dolphin's lungs.