Page "Hippopotamus" Paragraph 44

Mating occurs in the water with the female submerged for most of the encounter, her head emerging periodically to draw breath.

Baby hippos are born underwater at a weight between 25 and 45 kg ( 60 – 110 lb ) and an average length of around 127 cm ( 50 in ) and must swim to the surface to take their first breath.

A mother typically gives birth to only one hippo, although twins also occur.

The young often rest on their mothers ' backs when in water that is too deep for them, and they swim underwater to suckle.

They also will suckle on land when the mother leaves the water.

Weaning starts between six and eight months after birth and most calves are fully weaned after a year.

Like many other large mammals, hippos are described as K-strategists, in this case typically producing just one large, well-developed infant every couple of years ( rather than large numbers of small, poorly developed young several times per year as is common among small mammals such as rodents ).