Picture by Bert Glibbery.
A group of hippos, usually up to 40, is called a pod, herd, dale, or bloat. The word hippopotamus originated from the Greek and could be translated “river horse.” A hippo can run faster than a human and they have been clocked at 30 miles per hour for short distances. Hippos average 11 feet long!
Some pluralize hippopotamus as "hippopotamuses" and others as "hippopotami." No wonder many of us just use "hippos."