2018-05-23 / Columnists

Pets, Pets, Pets

Last week a group of Nassau Community College students brought donations to Last Hope, and then took a private tour. When kittens licked them, they were surprised their tiny tongues felt like sandpaper. Why would that be? Perhaps the following poem gives the reason:

Cat Kisses
Sandpaper kisses
on a cheek or chin
that is the way
for a day to begin.
Sandpaper kisses
a cuddle and a purr-
I have an alarm clock
that’s covered with fur.
–Author Unknown

The imagery is lovely but a furry alarm clock is not the biological basis for a cat’s rough tongue. Actually it feels that way because little hooked papillae (barb-like hairs) facing toward the back of the mouth, cover the top surface of a cat’s tongue. These stiff projections act like the bristles of a brush (or the teeth of a comb) so cats can groom efficiently. The spines are made of keratin like our fingernails, and each spine is shaped like a miniature cat claw.

Close-up of the backwards barbs on a cat's tongue Close-up of the backwards barbs on a cat's tongue The downside to the backward-facing barbs is anything the cat collects on her tongue will usually end up getting swallowed, and may end up as hairballs. The barbs on the tongue also make it dangerous if a cat gets some yarn, string or tinsel in his mouth because he won’t be able to spit it out.

Grooming is more than feline beautification. It’s a survival skill which evolved in the wild. After a cat has eaten his prey he will groom to remove all traces. This is an important strategy because he doesn’t want to alert other prey in the area to his presence by smell. Additionally, a cat is small enough to be predator or potential prey. Removing traces of a fresh kill would be important to his own safety as well.

Cats groom themselves for other reasons. In addition to detangling their fur, grooming removes parasites and their eggs. It also redistributes oils produced by the cat’s skin that provide the fur with some waterproofing. Some vets advise not to bathe your cat because you are removing these protective oils.

Grooming is a feline social skill. It’s a way to show trust between cats. Friendly cats tend to groom each other. Kittens start grooming one another by the time they’re five weeks old. Sometimes this behavior continues into adulthood, with bonded cats spending time grooming mutual places hard to reach. If a cat trusts you, it will groom its human.

Grooming helps cats keep cool. Although they have some sweat glands in their paws, cats don’t sweat like we do when it gets too hot. By dampening their fur with saliva, cats help themselves to cool down when the weather is extra warm.

Speaking of keeping cool, grooming serves as a distraction whenever a cat has an embarrassing moment. You’ve seen a cat fall off a counter and immediately start to groom herself, as if saying: “That brief lack of poise and coordination didn’t happen to me. You must be mistaken.”

It’s also thought the tongue barbs help do the delicate work of separating flesh from bone when a cat eats his prey. This adaptation is particularly important to the big cats like lions and tigers.

Scientists are now viewing adaptations like the spines on a cat’s tongue from a mechanical engineering perspective. According to an 11/21/16 article in Science Daily (quoted here), Alex Noel, a doctoral candidate in mechanical engineering, working at Georgia Tech, began exploring the odd “spines” on her own cat’s tongue, when she was helping to disentangle her cat after she licked a microfiber blanket and got her tongue stuck to it. Noel saw the Velcro-like hooks which glide over the fur until the hook catches a tangle or a snag.

“When the cat’s tongue hits a snag, it pulls on the hooks, which rotate to penetrate the snag even further. Like a heat-seeking missile for snags, the hook’s mobility allows the cat to better tease tangles apart,” said Noel.

Noel described this concept, which she compares to using stiff versus soft hairbrushes, and what it might enable as a practical application for people.

“Most hairbrushes have spines that stick straight out. When hair collects on the brush it forms a thick mat that must be removed by hand,” Noel explained. “The cat’s flexible spines make it easier to clean. When not in use, the spines on a cat tongue lie nearly flat against its surface, like overlapping shingles. This configuration provides openings in a single direction, enabling the mat of hair around the bristles to be removed with a single finger swipe. These openings face the cat’s throat and are also why cats swallow their hair and end up with hairballs.”

Taking the concept to the lab and using macro- and high-speed video equipment, Noel and colleagues were able to zoom in and observe the unique shape and flexibility of the tongue spines during grooming. “In terms of shape and sharpness, it reminds me of cat claws. And this opens yet another question of why all claws are shaped so similarly,” Noel said.

To help explore their theories, the researchers became the first group to 3-D print a cat tongue model at 400% scale. They learned both the cat tongue and model are very good at cleaning and removing tangles in fur samples. They also discovered the cat tongue is self-cleaning since it’s easy to remove hair beneath the spines by simply brushing the tongue from tip to end.

Findings may have important implications in soft robotics, where researchers are still struggling to find ways for soft materials to grip surfaces. “The cat tongue is flexible, but it can pull apart tangles in fur,” Noel said. “So we’re trying to develop a cat tongue-inspired surface based on our 3D-printed mimic. The flexibility of cats’ tongue spines may have broad-reaching applications from an easy-to-clean hairbrush to wound cleaning within the medical field, and might even be used to create soft robots that can more gently interact with humans.”

For Adoption at Babylon Town Shelter (631-643- 9270) Lamar St. W. Babylon: “Hercules” 8-15 did well at his first off-site adoption event. He’s a handsome Lab/Husky who loves to play ball. “Gracie” 8-167- is a dilute calico, six years old. She lived with adults and kids, and kneads like a kitten.

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