Anatomists say that if they had only known of the hippopotamus from fossils, they never would have guessed that it spent so much of its life in the water.  Indeed, its nickname is river horse.  The eyes, nostrils and ears are high on the head to facilitate this semi-aquatic lifestyle.  The hippo's thick skin, ironically, is very susceptible to sunburn.  What do they eat?  They're vegetarians.  They come out of the river and onto the plains at night to graze.   While staying at the Mara River Camp we were warned to look around before stepping out of our tents, and to stay inside if we had a hippo in the front yard.  One night I woke up to a chomp, chomp, chomp and there was a mama hippo with a tiny baby only 30 feet from my door.  I assumed she was staying close to the river so that her calf would be reasonably safe from lions and hyenas.  I didn't challenge her right to be there!