There are two types of hippo: the Common Hippo and the lesser known Pygmy hippo. Common hippos reside in large groups consisting of one male and many females. Pygmy hippos prefer to live alone. Hippos are endangered species as poachers top prizes are a pair of hippo tusks.
Male common hippos mark their territory by spinning their tail like a fan and flicking poo everywhere. Also, male hippos mark their water territory by omitting dung into their lake.
Hippos yawn at rivals. No, not because they're tired. Because they like to show off their huge tusks. Male hippos get into gigantic fights over territory, baring their teeth, opening their mouths and trying to bite the other one to death, or at least seriously injure them.