Hippopotamus also called hippo or water horse, amphibious African ungulate mammal. Hippopotamuses love water, which is why the Greeks named them the river horse. Hippos spend up to 16 hours a day submerged in rivers and lakes to keep their massive bodies cool under the hot African sun. Hippos are very loud animals. Their snorts, grumbles and wheezes have been measured at 115 decibels about the same volume as you'd get when 15 feetfrom the speakers at a rock concert. These booming creatures also