Why Do Beavers Have Bright Orange Teeth?

Beavers usually shy away from humans, but if you ever get a chance to look at one up close, pay particular attention to those wood-gnawing front teeth: They're orange or reddish-brown in color. No, it's not because they're rotting from chomping through all those logs; in fact, just the opposite is true. A beaver's tooth enamel contains iron, which works even better than fluoride in preventing tooth decay. It also makes their incisors very strong, so they can get those dams built in no time. What's more, a beaver's teeth have hard enamel in front but softer dentin in back, meaning that when they gnaw, they are actually sharpening their teeth -- which is important, since their front teeth never stop growing. Inspired by the beaver's unique dentition, researchers are investigating whether there is a less-colorful way to incorporate iron into human teeth.

Bite into some beaver facts:

• Beavers are the largest rodents in North America and Asia, and are second in size only to South America's capybara.
• Beavers really are "busy" creatures, often working through the night to build dams and lodges.
• During the Pleistocene epoch, the now-extinct giant beaver grew to 8 feet (2.4 m) in length and 200 pounds (90.7 kg) in weight.