Hippos spend up to 16 hours every day submerged in water or wallowing in mud. This keeps their thick skin from drying out in the hot African sun. They have a natural sunscreen — a pink oily liquid that oozes from their skin and protects them from sunburn and keeps their skin from cracking.
At dusk, hippos come out of the water to graze on grass. A single hippo can eat up to 40 kilograms of grass in one night — about the weight of a large dog. They can walk several kilometres from the river to find enough grass, then return to the water before dawn.
Hippos are surprisingly fast on land despite their barrel-shaped bodies. They can run at around 30 kilometres per hour over a short distance — faster than most people can sprint. In the water, they do not really swim; instead they bounce along the riverbed in slow-motion leaps.
Baby hippos, called calves, are born underwater and can hold their breath from their very first moments. A mother hippo is very protective and keeps her calf close at all times. Hippos are very social animals and live in groups of ten to thirty individuals, all resting together in the same stretch of river.