The capybara (Hydrochoerus hydrochaeris) is the largest rodent in the world, followed by the beaver, porcupine, and mara. Its closest relatives are guinea pigs and rock cavies, and it is more distantly related to the agouti, chinchillas, and the coypu. Native to South America, the capybara inhabits savannas and dense forests and lives near bodies of water. It is a highly social species and can be found in groups as large as 100 individuals, but usually lives in groups of 10–20 individuals. The capybara is not a threatened species and is hunted for its meat, hide and also for a grease from its thick fatty skin which is used in the pharmaceutical trade.
The capybara has a heavy, barrel-shaped body and short head, with reddish-brown fur on the upper part of its body that turns yellowish-brown underneath. Its sweat glands can be found in the surface of the hairy portions of its skin, an unusual trait among rodents. The animal lacks under hair, and guard hair differs little from over hair. Adult capybaras grow to 107 to 134 cm (3.51 to 4.40 ft) in length, stand 50 to 64 cm (20 to 25 in) tall at the withers, and typically weigh 35 to 66 kg (77 to 146 lb), with an average in the Venezuelan llanos of 48.9 kg (108 lb). The top recorded weights are 91 kg (201 lb) for a wild female from Brazil and 73.5 kg (162 lb) for a wild male from Uruguay. Capybaras have slightly webbed feet and vestigial tails. Their hind legs are slightly longer than their forelegs; they have three toes on their rear feet and four toes on their front feet. Their muzzles are blunt, with nostrils, and the eyes and ears are near the top of their heads. Females are slightly heavier than males.