[Intro]
 
It doesn’t matter who you are! 
 
Whether you’re a girl or a boy, young or old ---
 
--- no matter what part of the world you call home, every single person on Earth has one.
 
A belly button!
 
But have you ever wondered why we have belly buttons?
 
Every living thing that grows inside of a mother has a belly button. So it’s not just us humans that have them. Lots of other animals have belly buttons too --
 
-- but … not robots. 
 
Belly buttons—which doctors call navels—are basically scars that we’re born with.
 
So how do we all get these little round buttons on our bellies?
 
Well, as a baby grows inside of its mother, it floats around in fluid inside the mother's belly. 
 
But the baby can't breathe air or eat food on its own before it’s born. So it needs something called an umbilical cord. 
 
The umbilical cord is a flexible tube that carries oxygen and nutrients from the mother to the baby. 
 
So, everything that the mother eats, drinks, and breathes, she shares with her baby through that cord!
 
And your belly button marks the spot where your umbilical cord was once attached to you when you lived in your mother’s belly.
 
Now, when a baby is born, they can breathe and eat on their own. Even though the newborn still needs help from mom and dad, they don't need an umbilical cord anymore. 
 
So when human babies are born, the person delivering the baby just cuts the cord.
 
After a few weeks, the last bit of the cord that’s left on the baby’s belly falls off -- kinda like an old scab -- and the baby is left with--yup!--its very own belly button.
 
Now, the same thing happens for many other mammals that grow inside their mothers -- including dogs, cats, chimps, and gorillas. 
 
It’s hard to find the navels on really furry animals, like your pet dog, but they’re there, underneath all that fur. 
 
Most animals’ belly buttons are small and hard to spot, but chimpanzees and gorillas have belly buttons that actually look a lot like ours.
 
And in the case of animals, the mom just cuts the cord by biting it off!
 
Now, Squeaks, don’t feel too left out -- because not all animals have belly buttons. 
 
Animals that lay eggs, like most birds and reptiles, don’t have belly buttons like we do! That’s because they’re hatched from eggs, so they’re not connected to their mothers by a cord. 
 
But for those of us who do have them, now we know where belly buttons come from! 
 
It may not be super-useful for you anymore--but it was extremely important to you before you were born!
 
So thanks, belly buttons!
 
If you’d like to find out more information about other parts of the human body, or anything else, just let us know! Have your parents help you leave a comment or send us an email at kids@thescishow.com.
 
Thanks for joining us for SciShow Kids, and we’ll see you next time, here at the fort!