Hippos
Hippopotamuses, once known as river horses by the Greeks, love spending their days in the water. They can spend up to 16 hours cooling off in the lakes and rivers of Africa. They also have the ability to breathe underwater for up to five minutes. While they look too plump and cuddly to be the least bit dangerous, they are surprisingly fast runners with the ability to move at up to 19 miles per hour. Hippopotamuses are mainly herbivores, but they do tend to get territorial and aggressive toward possible threats.