Every rodent has two incisors in its upper jaw and two its lower jaw. Rodents must continuously gnaw at things to keep their teeth from growing too large.
There are over 2000 species of rodent. There are more rodent species than species of any other type of mammal. Rodents make up 40% of all mammal species.
Rodents can be found on every continent except Antarctica.
While many rodents are small, the capybara, the largest living rodent on Earth, can weigh more than 100 pounds.
The African pygmy mouse and the pygmy jerboa, two of the world's smallest rodents, weigh less than half an ounce.
You can find out more about different kinds of rodents by clicking on the links below.