Capybara

A 65-kilogram rodent

Capybaras are the world’s largest rodents — adults can weigh up to 65 kg, roughly the same as a large adult human. They’re close relatives of guinea pigs (Cavia porcellus) and share the characteristic rodent skull and ever-growing front incisors, just at a dramatically larger scale.

Their bodies are barrel-shaped, nearly hairless on the belly, with a coarse, sparse coat of reddish-brown or grayish hair. They have no tail.

A life in water

Capybaras are highly adapted for a semi-aquatic existence:

• Webbed feet — between each toe, partial webbing aids swimming
• Eyes, ears, and nostrils positioned high on the head — can be almost fully submerged with senses still functioning
• Excellent swimmers — can stay underwater for up to 5 minutes when evading predators (jaguars, anacondas, caimans)
• Spend midday in water — to escape heat in the open tropical environment

The internet’s favorite animal

In the 2020s, capybaras became a phenomenon on social media largely because of genuine footage of them coexisting peacefully with every other species — ducks resting on their backs, monkeys sitting on their heads, birds perching on them without reaction. The capybara’s extreme calm around other animals appears to be a genuine behavioral trait, not staged. In captivity, capybaras have been documented befriending dogs, cats, birds, ducks, and even crocodilians.

Ecological role

Capybaras are major grazers on South American river plains, consuming 3–4 kg of grass daily. They’re a keystone prey species for all major South American predators — jaguars, pumas, caimans, anacondas, and ocelots. Their dung supports aquatic plant growth and provides habitat for river insects.