Besides pouncing, purring, and pestering their owners for treats, cats spend much of their waking time licking themselves. Now, scientists have shed light on how sharp, tiny cones on cats’ tongues give their coats and skin a deep clean, instead of merely spreading their spit around.
Researchers created 3D scans of tongues collected postmortem from a domestic cat, a bobcat, a cougar, a snow leopard, a tiger, and a lion. The cones—or papillae—of all species sported hollow, half pipe–shaped cavities on their tips. By exploiting a property in water known as surface tension, wherein cohesive forces between water molecules keep them stuck together in a droplet and adhesive forces help the droplet stick to the papillae, these U-shaped cavities help cats move droplets of saliva through their upper layers of fur into deeper layers and onto the skin.
Slow-motion footage of several housecats grooming revealed the felines flared their tongues outward as if taking a big lick of an ice cream cone so the papillae stood perpendicular as they move through the fur. This motion helps maximize how much fur each papilla can reach, the team reports today in the Proceedings of the National Academy of Sciences.
But cats don’t just lick themselves to stay clean. Saliva helps them cool off, according to thermal imaging—an important tool, as cats only have sweat glands on the leather of their paws.
The scientists have used the findings to create a “tongue-inspired grooming [TIGR] brush” that mimics a cat’s tongue with 3D-printed papillae embedded in a flexible silicone pad. Compared with a regular, stiff-bristled hairbrush, the researchers say the TIGR brush tugged less as it passed through human hair, and was easier to clean. The brush could even help deliver medications directly to cats’ skin, the team says. And for those of us who love our pets but not their shedding, the cat comb provides an easy way to get fur off the couch.