The capybara (Hydrochoerus hydrochaeris) is definitively the largest rodent in the world, holding the title as the largest living species within the entire order Rodentia. This mammal is a native of South America, inhabiting the dense forests and savannas across nearly every country on the continent except Chile. Its semi-aquatic nature means it is always found near bodies of water, such as rivers, lakes, and marshes.
Measuring the Capybara’s Size
These animals possess a heavy, barrel-shaped body that can reach a length between 106 and 134 centimeters, or approximately 3.5 to 4.4 feet. At the shoulder, they stand approximately 50 to 62 centimeters (20 to 24 inches) tall.
The average adult weight for a capybara typically ranges from 35 to 66 kilograms (77 to 146 pounds). Females are often observed to be slightly heavier than males. Some exceptional individuals have been recorded at even greater sizes, with one wild female from Brazil reaching a confirmed weight of 91 kilograms (201 pounds).
These robust dimensions are supported by a coarse, reddish-brown coat and short limbs, which contribute to their distinctive appearance. Their size allows them to move comfortably on land, but their slightly webbed feet also make them powerful swimmers, a necessary adaptation for their water-based lifestyle.
The Defining Traits of Rodents
The classification of the capybara as a rodent is based on a specific set of biological characteristics shared by the entire Order Rodentia. This order is the largest group of mammals, accounting for over 40% of all mammal species found globally.
The defining characteristic for all rodents is their unique dentition. They possess a single pair of continuously growing, rootless incisor teeth in both the upper and lower jaws. These incisors are specialized for gnawing, featuring a hard enamel layer on the front surface and softer dentine behind.
As the softer dentine wears away more quickly during use, the enamel edge remains perpetually sharp, functioning like a self-sharpening chisel. Rodents also lack canine teeth, which creates a noticeable gap, known as a diastema, between their incisors and their cheek teeth.
Comparative Size of Other Large Rodents
The North American Beaver (Castor canadensis) is often cited as the second-largest rodent. An adult beaver typically weighs between 11 and 32 kilograms (24 to 71 pounds), with the heaviest individuals rarely exceeding 50 kilograms (110 pounds).
The Nutria (Myocastor coypus), another semi-aquatic species, usually averages a weight of 4 to 9 kilograms (9 to 20 pounds), with maximum weights reaching up to 17 kilograms (37 pounds). The Patagonian Mara (Dolichotis patagonum), a long-legged rodent native to Argentina, is also among the largest, but it reaches a maximum weight of only about 16 kilograms (35 pounds).
The capybara’s average weight of around 48 kilograms is roughly three to four times greater than the maximum size of the Patagonian Mara or Nutria. Even the beaver, a large and robust animal, is generally half the weight of a capybara.