These creepy flying mammals are among the most valuable creatures.

A savage little beast eats constantly to support its high metabolism.

This is a world-class beauty, which will bravely battle a Rattlesnake.

Invertebrates are among the most varied, and oldest, living organisms.

Frogs are certainly the reigning royalty in their wet kingdom.

Until 65 million years ago, giant Reptiles ruled the Earth. Dinosaurs have disappeared, but their multitude of descendants thrive in practically every kind of habitat North America offers.