Rodents are mammals with four distinctive incisors: two in the middle of the upper row of teeth and two below. These incisors keep growing back, up to five millimeters a week. The incisors wear out constantly because the rodents use them to crack nuts, fell trees, or dig holes in the ground, depending on the species of rodent.
The rodents’ skulls are built in such a way that they have a lot of power for gnawing. This also includes very strong chewing muscles. The whole skeleton is similar to that of other mammals.
Rodents can be found almost everywhere in the world except on a few remote islands and in Antarctica. All rodents have fur. The smallest and lightest rodent is a harvest mouse, reaching a maximum of five grams. The largest rodent is a capybara native to South America. It is over a meter long from head to bottom. It can weigh up to 60 kilograms.
Most rodents eat plants. Most of them can even digest wood. Few rodents also eat meat. Most rodents live on land. Some, like the beaver, have adapted well to life in the water. Still others, like porcupines, have evolved quills to protect themselves against their enemies.
Rodents, like other mammals, mate so that young animals grow in the abdomen of the female. Some species of rodents hibernate, such as the dormouse and marmots.
Rodents include squirrels, marmots, beavers, mice, rats, rabbits, hamsters, guinea pigs, chinchillas, porcupines, and many similar animals. The rodents form their own order within the class of mammals.