I think hippos are an interesting animal. 

 They are actually one of the most dangerous animals in the world so definitely worth knowing about.  What you have to watch out for is getting between them and water as when they are startled they run back to water and might trample you on the way.  They are quite grumpy too so if you poke them with a paddle them may chomp you.  They won’t eat you though as they are vegetarians.

They share a major weapon with lions: lions and hippos have very bad breath so if they want to stun you they breathe on you and then you are easier to defeat.