[MUSIC PLAYING]
ALEXIS NOEL: 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 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.
[MUSIC PLAYING]
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 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.
The small spines are called papilla.
They are composed primarily of keratin, just
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 3D 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, it's 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 the 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 papilla 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 hypothesized that it is linked to the fur density
and fur length.
So when you have fur that's very fluffy
and you try and compress it as much as possible,
you're going to 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 papilla
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 hair balls,
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 hair brushes, 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
papilla and seeing how it can be used
for human purposes or pet grooming purposes.
No other animal has developed a tongue to grooming like cats.
And by no means am I saying that the papilla on the cat's tongue
are used only for grooming.
It's really a multi-functional 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 hands 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 touching my cat
and petting my cat.
It actually makes me appreciate my cat just a little bit more.
I mean, I think there's still things about cats
that we haven't even discovered yet.
I think they're a really interesting animal to study.
LUKE GROSKIN: Hey, there, this is Luke Groskin, video producer
for Science Friday.
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