Capybara(Hydrochoerus hydrochaeris)

The capybara is the largest living rodent on Earth: an adult can weigh as much as 66 kilograms. In the past, however, much larger rodents lived in South America. One was Josephoartigasia monesi, whose remains were found in what is now Uruguay. It lived several million years ago. Researchers have arrived at different estimates of its weight based on the fossils, but agree that it was many times heavier than today’s capybara.

The capybara has a sturdy body covered in short, reddish-brown fur. It lives near rivers, lakes and marshes and is well adapted to life in the water. It has four toes on its front feet and three on its hind feet, with partial webbing between them. It is an excellent swimmer. Its eyes, ears and nostrils sit high on its head, allowing it to watch its surroundings and breathe while barely emerging from the water. When threatened, it may seek refuge there.

Capybaras are social animals, often living in groups of 15–20 led by a dominant male. They communicate through sounds and scent marks; a short alarm call can warn the others of danger. They can breed throughout the year, although mating is more common at the start of the rainy season. The well-developed young can follow their mother soon after birth, and other females in the group may help care for them. In the wild, capybaras are hunted by jaguars, caimans and anacondas, among other predators.