Considered to be one of the most dangerous animals in the world, they have very big teeth (almost 16cm in length) and a powerful bite, deadly enough to chomp a 3 metre-long crocodile in half. As they are aquatic, they feel very frightened when they are not in the water and will attack on the ground. They spend most of the day in the water and can stay submerged for up to six minutes, their extended bladder enabling them to take in more oxygen. As grazers, they will walk about at night in search of food.
Many of the most important aspects of their lives occur in water: they mate, deliver their calves and suckle their young in water. Hippos have 8cm of fat under their skin, but they have a thin layer of skin which is why they prefer to stay in water as long periods in the sun will burn them. Centuries ago English and Dutch settlers hunted down hippo in order to use their fat.
Lions, leopards and young crocodiles are some of their natural enemies; but fully-grown hippos are extremely difficult to take down. At two and a half to three tons this is perfectly understandable and despite their size, they are surprisingly fast, capable of running up to 36km/h.