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Rodents

Rodentia

Rodents are mammals in the order Rodentia, the largest order of mammals by number of species. Estimates vary by source, but there are over 2,000 living species, making rodents roughly ~40% of living mammal species. All rodents share a distinctive dental trait: one pair of upper incisors and one pair of lower incisors that are rootless and grow continuously, separated from the cheek teeth by a gap called a diastema (and rodents lack canine teeth). The incisors have hard enamel on the front and softer dentine behind, so gnawing creates a self‑sharpening, chisel-like edge. Rodents are found nearly worldwide—indigenous to almost every land area except Antarctica, New Zealand, and some oceanic islands, though humans have introduced certain species to new places. Their sizes range from tiny species weighing just a few grams to the capybara, the largest rodent, which can exceed 70 kg.

Rodents are mammals in the order Rodentia, the largest order of mammals by number of species. Estimates vary by source, but there are over 2,000 living species, making rodents roughly ~40% of living mammal species. All rodents share a distinctive dental trait: one pair of upper incisors and one pair of lower incisors that are rootless and grow continuously, separated from the cheek teeth by a gap called a diastema (and rodents lack canine teeth). The incisors have hard enamel on the front and softer dentine behind, so gnawing creates a self‑sharpening, chisel-like edge. Rodents are found nearly worldwide—indigenous to almost every land area except Antarctica, New Zealand, and some oceanic islands, though humans have introduced certain species to new places. Their sizes range from tiny species weighing just a few grams to the capybara, the largest rodent, which can exceed 70 kg.