Only elephants and some white rhinos are larger. At birth a hippopotamus weighs 30 - 60 kg, and it takes 4 to 5 years to reach maturity and a weight of 3600 kg. Hippo lips are about 2 feet wide.
Hippos can turn each ear in a different direction at the same time.
A bull hippos' bellow has been measured at 115 decibels. Hippos cannot float because their heavy muscles weigh them down and cause them to sink. 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.