As they wallow in the waters of a muddy river, hippos look like the layabouts of the African savannah. Yet this suggestion of lethargy disguises their potential for terrifying ferocity. Hippos are territorial animals in water and not afraid to intimidate rivals and predators invading their space. They are also known to attack humans that get too close. A hippo’s ivory tusks – actually extended canine teeth – make for formidable weapons. Together with a wide gape and powerful jaw muscles, they give the hippopotamus a killer bite. Swimming hippos are particularly dangerous because their buoyancy allows them to move their bulk with surprising speed. An adult could easily capsize a canoe.