Rodents (from Latin rodere, 'to gnaw') are mammals of the order Rodentia (/roʊˈdɛnʃə/), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity.
