The order Rodentia encompasses an immense diversity of mammals, from tiny pygmy mice to species of a much more substantial size. This group is defined by a single pair of continuously growing incisors in both the upper and lower jaws. That distinction belongs to a semi-aquatic herbivore native to South America.
The Capybara
The world’s largest living rodent is the capybara (Hydrochoerus hydrochaeris). It weighs between 35 and 66 kilograms (77 to 146 pounds), with some individuals reaching up to 79 kg (174 pounds). Standing about 0.6 meters (2 feet) tall at the shoulder, they measure up to 1.3 meters (4.3 feet) in length, and females are often slightly larger than males.
The capybara has a heavy, barrel-shaped body, a large snout, and coarse, reddish-brown fur. For its semi-aquatic life, its eyes, ears, and nostrils are located high on its head, and its feet are partially webbed, making it an excellent swimmer.
Habitat and Behavior
Capybaras are native to South America, inhabiting a range of environments from Panama to Argentina. They are always found near bodies of water, such as lakes, rivers, swamps, and marshes. These animals prefer dense forests and flooded grasslands that provide both good grazing opportunities and the water they rely on for refuge from predators like jaguars and anacondas.
As herbivores, their diet consists mainly of grasses and aquatic plants. They are selective grazers, often choosing plants with high protein content. A notable behavior is coprophagy, where they ingest their own fecal matter to extract maximum nutrients from the tough cellulose in their food, a process that aids digestion.
Capybaras are highly social animals, typically living in groups of 10 to 20 individuals, though much larger temporary groups can form during the dry season around remaining water sources. These groups are complex, often consisting of a dominant male, females, and their offspring. They are known for their calm and gregarious nature, often observed resting peacefully alongside other animal species.
Other Giant Rodents
While the capybara holds the title of the largest rodent, other species are also notable for their size. The North American beaver (Castor canadensis) is the largest rodent in North America, typically weighing between 11 and 32 kg (24 to 71 lbs), although some can weigh more. At up to 4 feet long including their tail, they are formidable in size but do not reach the weight of an average capybara.
Another large rodent is the Patagonian mara (Dolichotis patagonum), found in the open plains of Argentina. Resembling a long-legged rabbit, the mara weighs between 8 and 16 kg (18 to 35 lbs). While impressive, its size is significantly less than that of the capybara.