Why do frogs have teeth?

"Not many people report being bitten by a frog, but many will notice the weird ooze that seeps out of a toad's skin when they're picked up. These are just two strange adaptations that have helped amphibians survive in their environment. That's also why salamanders need the ability to regrow limbs, or even part of their brain. Curious future scientists learn all about these awesome adaptations as well as other important topics such as the unique amphibian life cycle, all complemented by full-color, up-close photographs."--Publisher.