Hippos spend up to 16 hours a day in the water during daylight hours. They are not actually swimming most of the time — they are standing or sitting on the riverbed, rising to the surface to breathe every few minutes, even in their sleep! A hippo can hold its breath for about five minutes.
At night, hippos come out of the water to graze on grass. They can travel several kilometres in one night, following the same paths to their favourite feeding spots. A hippo can eat about 40 kilograms of grass in a single night — roughly the weight of a large dog!
Hippos make a wonderful range of sounds — grunts, rumbles, honks and wheezes that echo across the water. These noises help hippos communicate with each other. When a big group (called a 'bloat') is together in the water, the noise can be surprisingly loud and rather funny to listen to.
Hippos have an unusual trick: they produce a reddish, oily liquid from their skin that acts as a natural sunscreen and even helps fight bacteria. Scientists call it 'blood sweat', though it is neither blood nor sweat. It turns the hippo's skin a pinkish colour in the sun.