A funny video has recently been making the rounds online, showing seven capybaras (Hydrochoeris hydrochaeris) living at a zoo in Saitama, Japan, happily soaking in a jacuzzi filled with warm water. But who exactly is the capybara? It is the world's largest rodent, and yet (a reassurance aimed exclusively at those with an irrational fear of mice), its funny, endearing snout can hardly inspire revulsion. This peaceful mammal lives in small groups in the wetlands of South America. Here are a few characteristics you may not know about.

Who capybaras are

Capybaras can exceed one and a half metres in length, 65 kilograms in weight and 60 centimetres in height at the withers. Despite their large size, which makes them the biggest representatives of the rodent family, their closest relatives are guinea pigs (Cavia porcellus) and rock cavies (Kerodon rupestris). More distant relatives include agoutis (Dasyproctidae Bonaparte) and chinchillas (Chinchilla).

They are animals that live in lakes, ponds and rivers

Lakes, ponds, rivers and marshes are the capybara's preferred habitats. These animals spend most of their time in water, relaxing or nibbling on grass and aquatic plants — they can eat up to eight kilograms of vegetation per day. Thanks to their webbed feet they are excellent swimmers, and their eyes, ears and nostrils are located at the top of their heads, allowing them to keep almost their entire body submerged below the waterline, much like hippopotamuses. Capybaras can hold their breath for up to five minutes, enabling them to hide from predators such as jaguars, pumas and ocelots.

Capybaras have teeth that keep growing to compensate for wear

Like other rodents, they have two long, sturdy incisors used to gnaw on aquatic plants, bark, tubers and sugarcane. A capybara's teeth can exceed eight centimetres in length and grow continuously to compensate for the wear caused by constant use.

Capybaras are wild animals, yet owing to their gentle temperament they are often captured to be kept as pets. Fortunately, this is no longer possible in Italy — since 1996 it has been prohibited by law for private individuals to keep capybaras. It appears that many species regard them as the armchairs of the animal kingdom. Various species of birds, monkeys, rabbits and even other capybaras have been photographed perched, seated and sprawled across the broad backs or heads of these large rodents.