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Temporal range: 56–0 Ma
Late PaleoceneHolocene
Rodent collage.jpg
Clockwise from top left: capybara, springhare, golden-mantled ground squirrel, house mouse and beaver representing the suborders Hystricomorpha, Anomaluromorpha, Sciuromorpha, Myomorpha, and Castorimorpha, respectively.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
(unranked): Glires
Order: Rodentia
Bowdich, 1821

Hystricomorpha (inc. Caviomorpha)

Rodent range.png
Combined range of all rodent species (not including introduced populations)

Hystricomorpha (inc. Caviomorpha)

Rodents (from Latin rodere, "to gnaw") are mammals of the order Rodentia, 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 found in vast numbers on all continents except Antarctica. They are the most diversified mammalian order and live in a variety of terrestrial habitats, including human-made environments.

Species can be arboreal, fossorial (burrowing), or semiaquatic. Well-known rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, hamsters, and capybaras. Other animals such as rabbits, hares, and pikas were once included with them, but are now considered to be in a separate order, the Lagomorpha.

Most rodents are small animals with robust bodies, short limbs, and long tails. They use their sharp incisors to gnaw food, excavate burrows, and defend themselves. Most eat seeds or other plant material, but some have more varied diets. They tend to be social animals and many species live in societies with complex ways of communicating with each other. Mating among rodents can vary from monogamy, to polygyny, to promiscuity. Many have litters of underdeveloped, altricial young, while others have precocial (relatively well developed) at birth.

Species Maximum longevity

years († in captivity)

Adult weight





per year

Litter size

average (range)

House mouse (Mus musculus) 4.0 20 19 5.4 5.5 (3 to 12)
Naked mole rat (Heterocephalus glaber) 31.0 35 70 3.5 11.3
Black rat (Rattus rattus) 4.0 200 21 4.3 7.3 (6 to 12)
Brown rat (Rattus norvegicus) 3.8 300 21 3.7 9.9 (2 to 14)
Eurasian red squirrel (Sciurus vulgaris) 14.8 600 38 2.0 5.0 (1 to 10)
Long-tailed chinchilla (Chinchilla lanigera) 17.2 642 111 2.0 2.0 (1 to 6)
Guinea pig (Cavia porcellus) 12.0 728 68 5.0 3.8 (1 to 8)
Coypu (Myocastor coypus) 8.5 7,850 131 2.4 5.8 (3 to 12)
Capybara (Hydrochoerus hydrochaeris) 15.1 55,000 150 1.3 4.0 (2 to 8)
Species Lower limit (Hz) Higher limit (Hz) Specific calls
Human 20 23,000
Rat 200 76,000 High frequency ultrasonic "pleasure" call emitted at 50 kHz
Mouse 1,000 91,000 Distress call of young emitted at 40 kHz
Gerbil 100 60,000
Guinea pig 54 50,000
Chinchilla 90 22,800

Zoology, osteology, comparative anatomy
  • The Bruce effect: Pheromones from strange adult males cause females to terminate their pregnancies
  • The Whitten effect: Pheromones from familiar males cause synchronous estrus in a female population
  • The Vandenbergh effect: Pheromones from mature male house mice cause an early induction of the first estrous cycle in prepubertal female mice
  • The Lee–Boot effect: Pheromones from mature females cause the suppression or prolongation of oestrous cycles of other female house mice (and other rodents) when they are housed in groups and isolated from males
  • Pheromones from males or from pregnant or lactating females can speed up or retard sexual maturation in juvenile females
  • Before birth: In utero, fetal rats detect odor-bearing particles that come from their mother's diet and cross the placental barrier. Shortly after birth, newborn rats respond positively to these foods.
  • During nursing: Nursing rats receive information about their mother's diet through her milk. They prefer the foods she ate during lactation.
  • Weaning: When young rats are weaning and eating solid foods for the first time, they use adult rats as guides. They forage where the adults are foraging or where adults have previously scent-marked.
  • Adolescence and adulthood: When rats forage on their own, their food choices are influenced by social interactions that may take place far away from foraging sites. They smell foods on the fur, whiskers and especially the breath of other rats and strongly prefer the foods those rats had previously eaten. This inclines them not to eat poisons avoided by older rats.
  • McKenna, Malcolm C.; Bell, Susan K. (1997). Classification of Mammals Above the Species Level. Columbia University Press. ISBN . 
  • Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World: A Taxonomic and Geographic Reference. Johns Hopkins University Press. ISBN . 
    • Carleton, M. D.; Musser, G. G. "Order Rodentia", pages 745–752 in Wilson & Reeder (2005).
  • Carleton, M. D.; Musser, G. G. "Order Rodentia", pages 745–752 in Wilson & Reeder (2005).


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