Rodent teeth are the most distinctive feature. The incisors, which have two upper and two lower teeth, are present in all rodents. These incisors never stop growing and lack roots, unlike human teeth. Rodents grind their teeth together to prevent them from growing into their brains.
Rodents make up around 40% of all mammal species. Except for New Zealand, Antarctica, and a few oceanic islands, they are native to all significant land masses; however, human activity has since introduced them to the majority of these land masses.
The majority of rodents are tiny, muscular creatures with short limbs and lengthy tails. Their razor-sharp incisors are used for biting food, digging burrows, and self-defense. Though some have more diversified diets, the majority consume seeds or other plant material. They are sociable creatures by nature, and many of them have sophisticated social structures and communication channels. Rodent mating may be monogamous, polygamous, or promiscuous. While some have litters of altricial, undeveloped young, others are precocial from birth.
Most rodents weigh less than 3.5 oz, while the biggest species, the capybara, may weigh as much as 146 lb. Although they may have a broad variety of morphologies, rodents usually have short limbs and squat bodies.
