Let's play a guessing game.  Try to guess which animal is related to the hippopotamus.  Hippos are those big animals that have gray skin, small round ears, big jaws, round bellies, and live in Africa.  Hippos can weigh over 7,000 pounds, and they kill over 300 people every year.  (That is not a hint.)  Animals have changed over the thousands and thousands of years on Earth.  What animal family do you think hippopotamuses came from?  For each animal you guess, I will tell you some cool things that connect the hippo to that animal.  We are going to try and guess from way over here in America.  

Start guessing!

Is it a pig?

No, the hippo is not related to the pig.  That is a great guess, though.  They do have those big nostrils and they do roll in mud.  However, hippos have an even better way to cool off.  Sunscreen is anything that keeps your skin from being burned by types of sunlight.  Hippos make their own!  It's red as blood and drips down their sides when it's hot outside.  Keep guessing.  I will tell you that the answer is bigger than a pig.

Nope, not a pig. Try again.


Is it a horse?

No, the hippo is not related to the horse, but they do have one thing that is kind of like a horse's.  They have a webbed hoof.  A webbed hoof is like the webbed foot of a frog mixed together with a hoof like a horse.  Hippos are the only animals on Earth who have them.  This lets them to run up to thirty miles an hour on land and swim faster than most animals.  Need another hint?  Look at the color of its skin.

Not a horse either. Try again.


Is it an elephant?

It is not an elephant, but hippos have skin that is very much like an elephant's.  A pachyderm is any animal with very thick skin.  This makes it hard to stop them from running you over.

A elephant may be big too, but keep trying.


Is it a rhinoceros?

It is not a rhinoceros either, but hippos can rush at people to scare them away, like rhinoceroses.  To be territorial means to fight for the place where you live when other things try to come into your home.  They come at you at thirty miles an hour with jaws that can cut a boat in half.  Now I will give you a big hint.  The hippos swim around in water . . .

Not a rhinoceros either, try again.


Not sure?  Then I will tell you how we figured out the hippo's closest relative.  They went under the water, where hippos can spend over six minutes without coming up for a breath, and they heard the hippos talk with each other.  Sonar is a way of telling where things are by sending waves through the water and listening to them bounce back.  Does that help?  No, it's not a bat . . .

Give up?  The hippo's closest relative is . . .  the dolphin!  They share a common ancestor, but hippos have changed a lot over a long time. They have grown thick skin, webbed hooves, have become very territorial, and make their own sunscreen.  Despite all these changes, they can still speak with sonar under the water, like dolphins.  This helps us find out where they came from and learn more about how they act.  There are a lot more things to learn about these animals!  I think you should read about it instead of trying to watch them in the wild, though.  Remember, they do not want you around, and they can bite a boat in half!

References:

National Geographic.  "Hippopotamuses"  Nat Geo, 2012.  <http://animals.nationalgeographic.com/animals/mammals/hippopotamus/>

Out of Africa.  "Hippo Fact File"  Out of Africa, 2010.  <http://www.outtoafrica.nl/animals/enghippo.html>