Some scientists think dolphins originally were on land millions of years ago. When they moved into the water, it was hard to catch fish. The nose was like ours. It was right on the front of their head. When there is a fish near them, and the dolphin has to breathe, it has to lift it's head up. In doing so, it can't keep its eye on the fish, and the fish swims away. Over time, the blowhole moved to the top of its head. Now, when it has to breathe, it just lifts its head a little up, and its eye is still on the fish!