Hippopotamus is third largest earth mammal. They weight in 1.5 to 2 tons. Hippopotamus are known for their big barrel shaped torso, short legs, hair less skin, big mouth and big teeth. Even thou Hippos are so big they could out run a human. There was a recording when Hippo was times for 30 mile range. Guess what?! Hippopotamus ran at a speed of 48 kilometers/hour. Imagine that! That's true that Hippopotamus have very short legs, but they run so fast. No wonder that hippos are called most vicious animals. They are also very territorial, but only in the water. May be because hippos are giving the birth under the water, may be this is the reason. And Hippopotamus have a gang of 5 to 30 members around. It's their little packs. they usually stay in the rivers or in the swamps. No wonder they look like pig, by the look of the body shape ;)I have read that Hippopotamus in Greek means horse river. Hippo means horse and potamos means river.