There's A Real Sonic The Hedgehog Gene (That Gives Cats Two Faces)
A little while ago, we were telling you about the Sonic hedgehog gene. That's a very real gene named after the video game character, and it's in many types of animals, including humans. It controls the development of organs, particularly in fetuses, and that means the Sonic hedgehog gene can do a lot of very strange stuff.
Take the case of Bettie Bee the kitten. Bettie Bee was born with two faces. Not two heads. One head with two faces. We've all heard of conjoined twins, which are two people that partly share a body, but Bettie Bee was just one kitten, as far as we could tell. We asked her if there were two souls constantly at war in there, but all she ever replied was "mew."
The photo of her above looks unreal, like we inexpertly messed with a single photo of a kitten in Photoshop, but Bettie Bee really did exist (though not for very long, as she was too good for this world). Cats like her are known as Janus cats. They form from a single fertilized egg, and the Sonic hedgehog gene works overtime and makes them doubly adorably, usually fatally so.
Extra eyes and mouths cause extra trouble. The body has other organs, though, which perhaps could work better the more you have. You've all heard the expression "as happy as a dog with two dicks," right? No? Well, we have, and while we don't have any stories today about two-penis dogs, we do know a bit about two-penis sharks.
Technically the organ in question isn't a penises (a fish doesn't have even one penis, let alone two). It's called a clasper. But a clasper is an external member that enters the female to deliver semen, and that makes it pretty penisy in our book. Male sharks have two claspers, even though only one plays any part in sex. Scientists were stumped for a while about why the second clasper existed—"one for show, and one for blow" was a theory that earned little praise from the scientific community.
It turns out the double claspers are due to that Sonic hedgehog gene. You can even give extra Sonic hedgehog protein to female shark fetuses, and they too will grow double shark penises, leading to utter chaos.
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Top image: Bettie Bee/Facebook