With over 2,000 living species placed in about 30 families, rodents are by far the largest order of mammals. Well over 40% of mammalian species belong to the order Rodentia.

Fear of mice and rats is one of the most common specific phobias. It is sometimes referred to as musophobia (from the Greek word for "mouse") or murophobia (for the family Muridae that encompasses mice and rats).

Hamsters will cannibalize their young if they're stressed out. It's a defense mechanism; if a hamster feels unsafe in their environment, they'll know their babies are in danger as well. The hamster response to this is to eat them instead of having them suffer. Things that can stress a mother hamster out include lack of food, a noisy environment, or too many babies to care for.

It could hardly be more apt, but a congregation of these spiky creatures is called a prickle.

This misconception started with a National Geographic article on lemmings in 1954. Lemmings do migrate, and sometimes in vast numbers. The Norway lemming (Lemmus lemmus) migrates in huge hordes when the population becomes too large, with some of their number drowning when they are pushed into the sea by the pressing momentum of the masses behind them. But the notion of a deliberate death march into the sea is false.

According to Guinness World Records, the oldest hamster ever was 4.5 years old, and was owned by Karen Smeaton of Tyne & Wear, United Kingdom.

The largest prairie dog colony on record was discovered by Vernon Bailey, an explorer and naturalist working for the United States Biological Survey in Texas around the turn of the 20th century. It covered some 25,000 square miles and contained an estimated 400 million prairie dogs.

Muskrats spend most of their time in the water and are well suited for their semiaquatic life. They can swim under water for 12 to 17 minutes. Their bodies, like those of seals and whales, are less sensitive to the buildup of carbon dioxide than those of most other mammals. And they can close off their ears to keep water out.

They grow up to sixty hairs from one follicle, whereas humans only grow one hair per follicle. As a result, chinchillas have about 20,000 hairs on each square inch of their bodies.

Often referred to as "nature's ottoman", these friendly critters don't ever seem to reject a ride-sharing request from another animal. A whole host of bird species, monkeys, rabbits, and even other rodents can be found seated, perched or laying on the back of a much-obliging capybara.