| Rodentia - gophers, mice, rats, squirrels, porcupines, beavers, chipmunks  This is the largest order of mammals. There are over 1,500 species of rodents. Rodents are found all over the world, except for in Antarctica, New Zealand and some ocean islands. They are found in a variety of habitats including rainforests, deserts, swamps,  tundra, coniferous and deciduous forests, and grasslands. They range in size from the smallest of mice to the pig-sized 
 capybara. Most species are omnivores, but some species are herbivores.  Some species, like chipmunks and hamsters, have pouches on the sides of their mouths for storing food. Some species, like squirrels, spend most of their time in trees, other species, like beavers, spend a lot of time in the water. All rodents have one thing in common, they have specialized teeth for gnawing. They have a pair of sharp, chisel-like upper and lower 
 
 incisors that are continuously growing! The front of the 
 
 incisors is covered with  thick protective layers of 
 enamel. The back side of the incisors has no enamel. As rodents gnaw their food, the back side of their incisors wears away, this keeps the edges of their incisors nice and sharp! They don't have canine teeth, so their is a gap between their incisors and their molars. This gap makes it easier for them gnaw with their their incisors! 
 
                  
                    | Families |  
                    |   Abrocomidae (chinchilla rats) 
  Anomaluridae (scaly-tailed squirrels) 
  Aplodontidae (mountain beaver) 
  Bathyergidae (mole rats) 
  Calomyscidae (mouse-like hamsters) 
  Capromyidae (West Indian hutias) 
  Castoridae (beavers) 
  Caviidae (cavies, guinea pigs, maras, capybaras) 
  Chinchillidae (chinchillas, viscachas) 
  Cricetidae (New World rats, mice, voles) 
  Ctenodactylidae (gundis) 
  Ctenomyidae (tuco-tucos) 
  Cuniculidae (pacas) 
  Dasyproctidae (acuchis, agoutis) 
  Dinomyidae (pacaranas) 
  Dipodidae (birch mice, jerboas, jumping mice) 
  Echimyidae (spiny rats) 
 
  Cuniculidae (pacas) |  Erethizontidae (New World porcupines) 
  Geomyidae (pocket gophers) 
  Gliridae (dormice, hazel mice) 
  Heteromyidae (kangaroo rats, pocket mice) 
  Hystricidae (Old World porcupines) 
  Muridae (Old World mice and rats, gerbils) 
  Myocastoridae (nutrias) 
  Nesomyidae (African/Malagasy endemic rats) 
  Octodontidae (degus, rock rats, viscacha rats) 
  Pedetidae (springhare) 
  Petromuridae (dassie rat) 
  Platacanthomyidae (Malabar spiny dormouse) 
  Sciuridae (squirrels, chipmunks,  prairie dogs ) 
  Spalacidae (blind mole rats, African mole rats) 
  Thryonomyidae (cane rats) |  |