Got Your Cat Tongue?

Ph.D. student Alexis Noel studies feline tongues, and has discovered interesting qualities.

TRANSCRIPT

Ever wonder how cats manage to grab their food and water?

If you take a close look at a cat tongue, you'll see small spines that resemble hooks called papillae.

Alexis Noel, PhD student of mechanical engineering, studies feline tongues and has discovered some interesting qualities.

Our partner, Science Friday, has the story.

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I have a cat at home named Murphy... and he thought that the blanket that he was on smelled really tasty, and he ended up getting his tongue stuck in the blanket.

And so I went to help detangle him, and, you know, the scientist in me was like, 'What just happened?'

Well, everybody keeps saying cat tongues are like sandpaper, right?

But how does sandpaper catch on a blanket?

So I took that question with me back to the lab and looked a little closer at cat tongues, and thus started the cat-tongue study.

♪♪ My name is Alexis Noel.

I'm a PhD student in mechanical engineering, and I study tongues.

You know, when you think about biomechanics and you're wanting to replicate the animal world to help some sort of technology for humans, you think of things like hands or you think of things like walking, and the tongue seemed to be a very interesting topic that no one had bothered to look at.

So my collection of tongues -- I think it's up to 23 now.

When I dig through that freezer, it's always an adventure.

I got tongues from a local taxidermist.

I got some from Zoo Atlanta and University of Tennessee Veterinary School.

I have cat tongues ranging from domestic cat to mountain lion, other animal tongues, like pig tongues.

I even have a monkey tongue.

There's all sorts of different tongues out there.

There's tongues with spikes on them, like penguins.

There's tongues that have a very sticky fluid on them, to help catch insects, typically.

Tongues have evolved for specific functions.

So let's think about cats.

When you look at the surface of the cat tongue, you'll see all sorts of different spines on the surface.

These small spines are called 'papillae.'

They are composed primarily of keratin, such as like our fingernails.

When I started this study, my first thought was that these cat spines are used to rasp meat off bones, because that was the general consensus.

So I actually took a dissected cat tongue and I took a piece of pork, and I basically grated the pork with this cat tongue to see what would happen.

And, lo and behold, the cat tongue was able to rip that meat off of that pork slab very, very easily.

And I stuck it under the sink to wash it, and the cat tongue was dyed red, and I thought that was very strange.

It should be able to wash off easily, and I could not get that color out of these spines.

And so I pulled one of the spines out from the cat tongue and stuck it in a CT scanner to get a beautiful 3-D image, and when that image came out of the CT scanner, it was fascinating.

We saw this tiny little scoop, this little U-shaped -- I call it an ice-cream scoop.

My mind was blown.

That was totally contradictory to all of the previous literature.

So, the purpose of the tiny little scoop in these cat spines in the mouth is quite interesting.

These little scoops hold saliva, very similar to how a drinking straw kind of pulls up water when it's in your cup.

These little spines will pull in water and store water in the spines.

So when a cat goes to groom and it lodges these spines deep into the fur, it's able to distribute that saliva deep within its fur, all the way down to its skin, which better helps it clean its fur.

And it's used beyond just grooming.

We've shown that the fluid-dispensing properties of these papillae can help with control of body temperature in cats, so being able to distribute saliva deep within their fur can help with that cooling.

And we found that this scoop shape was not just in a domestic-cat tongue.

In fact, these scoop shapes were found from house cats all the way up to tigers, and what's cool is that these little spines are the exact same size from house cat to tiger, which is very strange in the animal world.

Generally, you have things that scale, but these little tongue spines do not.

Why don't these spines get bigger as the cat gets bigger?

We hypothesize that it is linked to the fur density and the fur length.

So when you have fur that's very fluffy and you try and compress it as much as possible, you're gonna compress down to a certain height.

What we found is that that height, from tigers to snow leopards to house cats, is always going to be less than the length of the papillae in the cat tongue.

Another unique feature of the cat tongue is that the spines all point towards the back of the throat.

So, if you've ever wondered why cats have hairballs, it's because the fur that they collect with their tongue can only go one direction -- down the throat.

But if you think about it in terms of application, like human hairbrushes, taking hair out of a hairbrush is a huge hassle.

It's really, really annoying.

So if you could have a hairbrush that, with one swipe of your hand, removes all of the hair, I think that's a pretty big advancement.

So, we are currently developing a cat-tongue-inspired brush, and we're taking all of these unique functions of the cat papillae and seeing how it can be used for human purposes or pet-grooming purposes.

No other animal has developed a tongue to grooming like a cat's, and by no means am I saying that the papillae on the cat tongue are used only for grooming.

It's really a multifunctional tool.

But when you pet your cat, you are rubbing your hand over its saliva-coated fur.

You're getting all sorts of different oils and different enzymes and saliva all over your hand.

So, is rubbing your hand on cat fur that's been coated in saliva just as gross as a dog licking your face?

I would say no.

I am still not grossed out by catching my cat and petting my cat.

It actually makes me appreciate my cat just a little bit more.

I mean, I think there are still things about cats that we haven't even discovered yet.

I think they're a really interesting animal to study.