This does not present a problem, since they can either paddle to stay afloat or simply walk along the river bottom. Feeding always occurs on land. However, courtship, birth and nursing takes place underwater. Adult hippos can stay underwater for five to six minutes. However, baby hippos can only stay underwater for twenty seconds.
Few animals can open their mouths as wide as hippos can.
They use this ability to scare away other animals. Around the turn of the eighteenth century, hippo tusks were used to make artificial teeth. When hippos fight each other, they use their teeth, toss water at each other, accost each other with a variety of sounds and swing their massive heads together. Although all hippos are herbivores and would rather run away than fight, several hundred people a year do not survive a close hippo encounters. In addition, hippos are more deadly than many feared predators, including lions.