How can frogs stay under water so long?

   When a frog is sitting on the bank of a stream, he breathes through his nostrils as you do. Air goes into his lungs, which are somewhat like your lungs. Then he dives under water, and he doesn't come to the surface as quickly as you have to when you dive. Why not? There is always some air mixed with water in a stream or pond, and a frog can take a little of it into his body through his skin.