Rodents are believed to have been on earth for more than 50 million years. They live on all continents except Antarctica and are distinguished by their incisor teeth, which continue to grow throughout their lifetime.
Rodents range in size from a few inches to many feet and from one ounce to 150 pounds, depending on species. Their unifying feature is their teeth: sharp, curved incisors that are optimized for gnawing and chewing. These incisors never stop growing, so rodents must continuously find ways to wear them down. Rats and mice are capable of six bites each second, and they can gnaw through concrete and metal. In general, rodents have highly-developed senses of vision, smell, and hearing. Some also have whiskers that are used to enhance their ability to feel their surroundings.
Common rodents like rats and mice have a maximum lifespan of 5 years, while marmots, chinchillas, and chipmunks may live 10-15 years. A single mouse can produce more than 50 offspring annually and is capable of becoming pregnant again just 24 hours after giving birth.