The capybara (Hydrochoerus hydrochaeris) holds the title of the world’s largest living rodent. Its broad, barrel-shaped body and distinctive semi-aquatic lifestyle set it apart from its smaller relatives. Native to South America, this herbivore thrives near bodies of water and belongs to a diverse group of rodents called Caviomorpha. To understand what animals are similar to a capybara, one must examine both its closest genetic kin and other large South American rodents that share a similar appearance or ecological niche.
The Capybara’s Immediate Family
The capybara’s most direct relatives are found within the family Caviidae, a group that includes guinea pigs and the less common maras. Molecular studies have placed the capybara, along with the rock cavies (Kerodon), into the subfamily Hydrochoerinae, confirming their shared lineage. This classification means the capybara is a giant version of the guinea pig.
The Caviidae family is divided into three main subfamilies: Caviinae (guinea pigs and true cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras and rock cavies). Although the capybara belongs to the genus Hydrochoerus, it shares many fundamental anatomical features with the smaller species in the Caviinae subfamily. They are all herbivores with blunt snouts, large heads, and virtually no tail. The capybara’s size, weighing up to 174 pounds, is a striking example of gigantism relative to its family members.
Distinctive Features of the Capybara’s Relatives
Despite being close genetic relatives, the capybara, the mara, and the guinea pig have evolved different adaptations in size, habitat, and social structure. The guinea pig (Cavia) is a small, terrestrial rodent typically weighing less than three pounds, with a compact body designed for life in scrub grasslands and savannas. It lacks the webbed feet and high-set eyes and nostrils that mark the capybara as a species uniquely adapted to water.
The Patagonian mara (Dolichotis patagonum), also a member of Caviidae, presents a distinct form, resembling a rabbit or a small deer with its long, powerful legs. Maras are cursorial animals, meaning they are built for running across the arid, open grasslands and scrublands of Argentina, a dry habitat compared to the capybara’s wetlands. Socially, maras are monogamous and live in small family groups, which contrasts sharply with the capybara’s highly social herds of ten to twenty individuals.
Other Large South American Rodents
Beyond its immediate family, other large rodents from South America share a resemblance to the capybara due to convergent evolution. The nutria, or coypu (Myocastor coypus), is often confused with the capybara because it is also a large, semi-aquatic herbivore with a geographic overlap in its native range. The nutria belongs to a different family, Myocastoridae, and is recognizable by its round tail and large, bright orange incisor teeth.
Another example is the paca (Cuniculus paca), a stocky rodent that lives near water sources in tropical forests. While it shares the capybara’s robust build and affinity for water, the paca is easily distinguished by its dark brown coat marked with rows of white spots and its nocturnal, solitary lifestyle. These animals are members of the Caviomorpha infraorder, demonstrating how different evolutionary paths can still produce large, ground-dwelling forms in the South American ecosystem.