The birds and the bees

So I was watching the Little Mermaid "trilogy" with my four year old Diva. And I got to thinking... So Ariel was a mermaid until she was the tender age of 16. Then she got married and had a baby. My problem with this is, if she was a fish for 16 years, she's never had a vagina before right? So she's never had her period. So   I would assume that she had it once she became a person... right? What was that like? Did Prince Eric try to explain tampons to her through the bathroom door?

Just some wholesome food for thought...