What was that funny, cute and awwwww-inspiring video of a cat that you last saw on the internet? Was it on one of the thousand Facebook pages, a WhatsApp forward, Instagram or on YouTube? Was it a cute kitty amazed by a laser beam on a wall; one trying to catch a fish floating on the screen of a smartphone or was it that beauty basking luxuriously in the sun, licking its fur to spotless brilliance?
Whatever you were watching, or even if you aren’t a ‘cat person’, you surely must have observed that cats spend much of their time (actually nearly 25 per cent of their waking hours) licking themselves. It is estimated that on an average, a cat spends nearly 2.5 hours licking its fur every day.
Ever wondered why would an animal spend nearly one-fourth of its waking time on an activity such as this? And what on earth has the grooming and cleaning industry got to do with this?
Cats like to remain clean, that’s true. But there is more to their infatuation for licking. Researchers say this also helps them remove excess heat and regulate body temperature. And now, armed with studies on cats (actually their multifarious tongues and the dynamics of their licks), bio-engineers are planning to devise devices that may make grooming a hell lot easier for humans and animals alike.
So, how does this happen? How are cats able to keep their fur spotless clean but dogs can’t? What can we learn from their tongues?
To answer this, Alexis C Noel and David L Hu, bio-engineers at the Georgia Institute of Technology, Atlanta (US), conducted a study and analysed tongue pattern of six different cat species – domestic cat, bobcat, cougar, snow leopard, tiger and lion (see photo below).
The study was published in the Proceedings of the National Academy of Sciences, one of US’s most reputed science journals, on December 4, 2018.
The team found that cats have thousands of hollow rigid spine-like structures on their tongue which help them wick saliva (moisture) deep into the fur and clean it. These spines are called filiform papillae (see photo below). Besides helping the tongue deliver saliva into the fur, papillae also act as a brush that helps in untangling and removing broken hairs from the skin.
Researchers say findings of the study will help the grooming and cleaning industry come up with more efficient products that rely upon the natural cleansing ability of a cat’s tongue. A direct use can be in the development of better-quality brushes.
What did the scientists do
To study the cleansing ability of a cat’s tongue and the role of papillae, the team collected post-mortem tongues of six cat species – domestic cat, bobcat, cougar, snow leopard, tiger and lion.
It then created 3D images of each tongue and observed the structure of papillae in them. Surprisingly, the size and structure of papillae in all six tongues was more or less the same (despite the size variation between a domestic cat, a tiger and a lion).
To study the dynamics of cat grooming, the team used sophisticated cameras capable of high-speed videography and recorded the tongue movement of a domestic cat when it was licking her fur. When the footage was played in slow-motion, the team saw the papillae in action.
It was observed that there are four phases in which a cat grooms itself — extension of the tongue, lateral expansion and stiffening of the tongue tissue, a sweep of the tongue through the fur, and finally retraction of the tongue in a U-shaped curl (see photo below).
“During expansion, the papillae rotate until they are perpendicular to the tongue. This allows the papillae to stand erect to increase their contact area with fur,” Dr Alexis Noel writes about her study.
Explaining it further, she says the 3D printed images (see below) show that a cat’s tongue has two regions of papillae. In the first region (from the tip to the middle part) the papillae are long. In the second half of the tongue (from middle to the throat) the papillae are shorter, softer but denser. “From the high-speed videos, we find that only the front half of the tongue is used during grooming,” she writes.