Hippopotamus

The river horse with pink sweat

A hippo lies in the water by day and comes out to eat grass at night. It can't swim — it walks along the river bottom! A hippo's skin makes 'pink sweat' — a natural sunscreen. A hippo looks gentle, but it's one of Africa's most dangerous animals — it fiercely defends its territory.

The hippopotamus (Hippopotamus amphibius) is Africa's third-largest land animal (up to 1.5 tonnes). Its name is Greek for 'river horse', but its closest relatives are whales and dolphins. Its skin secretes a red-pink fluid — an antiseptic and UV filter. It holds its breath for 5 minutes and even surfaces to breathe automatically while asleep. Its mouth opens 150°, its bite force is 8,100 newtons and its tusks are 50 cm. Each night it walks 5 km and eats 40 kg of grass. About 500 people a year are killed by hippos in Africa. It is hunted for meat and tusks (an ivory substitute); around 130,000 remain.

Fun facts

• A hippo's closest relative is the whale!
• A hippo makes 'pink sweat' — it's sunscreen.
• A hippo can't swim: it walks on the river bottom and surfaces to breathe even while asleep.