“Rodents are the largest order of mammals, with more than 2,000 species. They fall into a few major groups: squirrel-like rodents, beaver-like rodents, mouse-like rodents (the biggest group), and cavy-like rodents such as guinea pigs, chinchillas, porcupines, and capybaras.”
Roughly two out of every five mammal species on Earth is a rodent. They live on every continent except Antarctica, from Arctic tundra to tropical rainforest to desert dunes. What unites them is a pair of ever-growing, chisel-like front teeth in each jaw. What separates them is almost everything else: size, diet, lifestyle, and social life. This guide is your map to the rodent family tree, with examples you’ll recognize and links to our deeper guides.
What Makes an Animal a Rodent?
All rodents share a few key traits:
- Two upper and two lower incisors that grow continuously throughout life
- Enamel mainly on the front of those incisors, which keeps them self-sharpening
- No canine teeth, leaving a gap called the diastema between incisors and cheek teeth
- Powerful jaw muscles built for gnawing
Rabbits and hares look similar but belong to a different order, the lagomorphs, because they have a second, smaller pair of upper incisors. Curious whether capybaras really count? See are capybaras rodents. For a closer look at teeth, jaws, and digestion, read our rodent anatomy guide.
The Major Groups of Rodents
Scientists usually divide rodents into five suborders. Classification is still debated, but the groups below capture the big picture.
| Group | Nickname | Examples |
|---|---|---|
| Sciuromorpha | Squirrel-like | Squirrels, chipmunks, marmots, prairie dogs, dormice, mountain beaver |
| Castorimorpha | Beaver-like | Beavers, pocket gophers, kangaroo rats, pocket mice |
| Myomorpha | Mouse-like | Mice, rats, hamsters, gerbils, voles, lemmings, jerboas |
| Anomaluromorpha | Scaly-tailed | Springhares, scaly-tailed squirrels |
| Hystricomorpha | Porcupine- and cavy-like | Capybaras, guinea pigs, chinchillas, degus, porcupines, naked mole-rats |
1. Squirrel-Like Rodents
This group includes the squirrel family, one of the most familiar rodent families in the world. It covers tree squirrels, ground squirrels, flying squirrels, chipmunks, marmots, and prairie dogs. Dormice are also placed in this broad group.
- Tree squirrels: gray, fox, and red squirrels. See types of squirrels and red vs gray vs fox squirrels.
- Burrowers: groundhogs, marmots, and prairie dogs. See groundhog facts and prairie dog facts.
- Gliders: flying squirrels glide on flaps of skin between their legs.
- Sleepers: dormice are champion hibernators.
2. Beaver-Like Rodents
This smaller group includes beavers, the second-largest rodents on Earth, along with pocket gophers and the kangaroo rats and pocket mice of North American deserts. Kangaroo rats can survive without drinking water, getting moisture from the seeds they eat. Learn more in our beaver facts guide.
3. Mouse-Like Rodents
This is the biggest group by far, containing more than a thousand species. It includes the two largest rodent families, which hold the true mice and rats and the hamsters, voles, and lemmings. Most popular pet rodents come from here.
- Mice and rats: house mice, fancy rats, spiny mice. See our pet rat care guide and pet mouse care guide.
- Hamsters: Syrian and dwarf hamsters. See the hamster care guide.
- Gerbils: desert-adapted diggers. See the gerbil care guide.
- Voles, lemmings, and muskrats: see voles and lemmings and muskrat facts.
- Jerboas: hopping desert rodents, some weighing just a few grams.
4. Scaly-Tailed Rodents
This small African group includes springhares, which hop like tiny kangaroos, and scaly-tailed squirrels, which have rough scales under the tail that help them grip tree trunks. Many scaly-tailed squirrels can glide, even though they’re not closely related to true flying squirrels.
5. Cavy-Like and Porcupine-Like Rodents
This group has a fascinating history. Its members are found mainly in South America and Africa, and scientists believe their ancestors reached South America from Africa tens of millions of years ago, likely by rafting across a narrower Atlantic Ocean. Today the group includes some of the most distinctive rodents alive:
- Capybaras: the largest living rodents. Start with our capybara facts.
- Guinea pigs: see the guinea pig care guide.
- Chinchillas and degus: see our chinchilla and degu care guides.
- Porcupines: see porcupine facts.
- Nutria: see nutria facts.
- Naked mole-rats: nearly hairless, live in colonies with a single breeding queen, and are known for unusually long lives for their size.
Rodents by Size
Rodents range from a few grams to well over 100 pounds. Our rodent size comparison chart lines up 20 species from smallest to largest.
Rodents by Lifestyle
- Tree dwellers: squirrels, some dormice
- Burrowers: gophers, prairie dogs, mole-rats, groundhogs
- Semi-aquatic: capybaras, beavers, muskrats, nutria
- Desert specialists: gerbils, jerboas, kangaroo rats
- Gliders: flying squirrels, scaly-tailed squirrels
Social life varies just as much. Some rodents, like capybaras and prairie dogs, live in large groups, while Syrian hamsters live alone. See social vs solitary rodents.
How Rodents Evolved
The earliest rodents appeared more than 50 million years ago, and their gnawing teeth and fast reproduction helped them spread into nearly every habitat. Our rodent evolution guide traces the family tree, and our rodents by continent guide shows where each group lives today.
Need a Word Explained?
Terms like “hystricomorph” and “diastema” can be confusing. Keep our rodent glossary handy as you explore.
The Biggest Rodent Families
Within these suborders are dozens of families. A few of the most important:
- Muridae: Old World mice and rats, plus gerbils. One of the largest mammal families on Earth.
- Cricetidae: hamsters, voles, lemmings, muskrats, and New World mice and rats.
- Sciuridae: squirrels, chipmunks, marmots, and prairie dogs.
- Caviidae: guinea pigs, maras, and capybaras.
- Castoridae: beavers.
- Erethizontidae and Hystricidae: New World and Old World porcupines.
- Chinchillidae: chinchillas and viscachas.
Rodents as Pets
Only a handful of rodent species are commonly kept as pets, mostly from the mouse-like and cavy-like groups. If you’re considering one, start with our best pet rodents for beginners ranking or take our which rodent is right for me quiz. Wild species such as squirrels, beavers, and prairie dogs are best appreciated outdoors.
Frequently Asked Questions
How many types of rodents are there?
There are more than 2,000 rodent species, usually grouped into five suborders and around 30 or more families.
What is the most common type of rodent?
Mouse-like rodents are the most diverse group, and the house mouse and brown rat are among the most widespread mammals on Earth.
Are rabbits rodents?
No. Rabbits are lagomorphs, a separate order with an extra pair of small upper incisors.
What is the largest type of rodent?
The capybara is the largest living rodent.