If you've been groomed by a cat then you know their tongue is rough and scratchy - like sandpaper! It's not wet like a dog's tongue (that's why cats are not sloppy smoochers). And if you examine it closely you'll recognize that it's weird! You'll see that it's full of tiny barbs that face backward. Those are called papillae and they do a lot for a feline's daily life.
Let's take a closer, more scientific look, at the papillae on your kitty's tongue. Each barb is about 2 mm long and under magnification, they have a U-shaped cavity on the tip. Scientists have discovered that the hardness of each barb is similar to that of human fingernails! Every house cat has about 300 papillae on their tongue.
What does all this "hardware" do for your cat? They actually have a number of very important applications. First, for cats of all sizes, these barbs help them hold prey and scrape meat off the bone. So, they are important to the survival of cats all over the world.
Secondly, they aid in grooming in a number of ways. The barbs act as a sort of hairbrush to remove tangles, parasites, dirt, and debris. Furthermore, the U-shaped cavity on the barbs has an important function. The U fills with saliva while they groom which is distributed not in the fur but down to the skin to clean it. Also, in hot weather that little bit of saliva helps regulate their body temperature.
Lastly, our cat's tongue helps them to drink water. Cats have a very wide mouth so they can't drink or hold water like a dog does. A dog makes a little "cup" with their tongue, however, a cat can't do that. Your kitty uses the tip of their tongue to flick a column of water into the air which they quickly catch in their mouth. Your cat does this 4 times a second! Once they get enough water, about every 4th or 5th tongue-full, they swallow. Now that's amazing!
You may be wondering if there are there any downsides to your cat's barbed tongue? Well... the barbs make it nearly impossible for your cat to "spit" out certain things, like the fur they groom up (hence hairballs!) and it's why most vets recommend that cat's don't play with yarn, as it can stick to the barbs on their tongue and they may swallow it.
All in all your cat's tongue is an engineering marvel! So next time your cat is grooming you - enjoy the scraping! And remember cats only groom others that they trust and love!