Hippopotamus: The semi-aquatic giant with eyes on top of its head

The hippopotamus is the "big one" of Africa's rivers and lakes: round-bodied with thick skin, it looks placid but is enormously strong. It is the third-largest land animal, weighing 1.5 to 3 tonnes. Let's meet it.

Its body

The hippo's cleverest design is that its eyes, ears and nostrils all sit on top of its head. So when it sinks its body underwater, only those three need to show — letting it soak, watch its surroundings and breathe at the same time. Its skin is thick, protecting it from sunburn, and it secretes a pinkish "sweat" — in fact a natural sunscreen and antibacterial — that looks like a coat of pink sun cream.

Where it lives and what it eats

The hippo is a plant-eater. By day, herds soak in rivers and lakes to keep cool and avoid the sun; at dusk, hippos come ashore to graze, walking several kilometres and eating about 40 kilograms of grass a night. Slow as it looks, a hippo can sprint very fast over short distances.

Why it is dangerous

The hippo is one of Africa's most dangerous animals. It is highly territorial, and especially when with a calf it will not hesitate to drive off anything that comes close. So even watching from a distance, in a zoo or the wild, strict safety rules must be followed.

A note for grown-ups

You could look at a photo of a soaking hippo with a child and find its eyes, ears and nostrils. Let them discover that they are all on top — so it can breathe and watch even with its body underwater. Use that observation to think about how structure adapts to habitat.