Rodentia is an order of placental mammals. Members of this order are called rodents. The order comprises 2,360 extant species, which are grouped into 511 genera. The largest order of mammals, rodents comprise about 40% of all mammal species worldwide. They are native to all major land masses except for Antarctica, and can be found worldwide. They live in a variety of habitats, particularly forests, grasslands, and shrublands, but also savannas, wetlands, deserts, and rocky areas. Most rodents are small animals with robust bodies, short limbs, and long tails. They range in length from the African pygmy mouse, at 4 cm (2 in) plus a 2 cm (1 in) tail, to the capybara, at 134 cm (53 in) plus a 2 cm (1 in) tail.