What if cats had no whiskers?

Look at a cat's face. Can you see the long whiskers?

Whiskers help a cat feel things. What if a cat had no whiskers at all?

Cats have long, stiff whiskers on their faces, and some shorter ones in other places too. They look a bit like hairs, and they are hairs, but very special ones.

What if a cat had no whiskers? Would it notice? In this thought experiment, you can explore three of a whisker's jobs: squeezing through gaps, feeling the air, and moving in the dark. Then decide what a cat without whiskers might find hard.

Whiskers, or vibrissae, are specialized tactile hairs. Britannica describes them as touch receptors that are vital to a cat's hunting, and the University of Michigan's Animal Diversity Web says they help house cats get around obstacles in low light by sensing changes in airflow.

A thought experiment can isolate their role: remove the whiskers and ask which everyday tasks would get harder. The answers are ideas built on what whiskers are known to sense, not results from an experiment on cats.

A cat has whiskers on its nose, over its eyes and under its chin.

It even has some on its front legs! They all help it feel.

Whiskers grow on a cat's muzzle, above its eyes and under its chin. Cats also have some on the underside of their lower front legs. They are thicker and stiffer than normal hairs and taper to a point at the tip.

Cats can move their whiskers. They can spread them out to the sides, pull them back against the face, or push them forward to feel things close to the mouth.

Veterinarian Marty Becker describes whiskers as specialized tactile hairs, also called sinus hairs or vibrissae, found on the muzzle, above the eyes and beneath the chin, and in cats also on the underside of the lower foreleg (carpal hairs). They are thicker than ordinary hairs and tapered.

Whiskers are mobile: cats extend them sideways, pull them back against the face, or point them forward to find and pick up things with the mouth. Britannica adds that the hairs of the eyebrows, cheeks, chin, legs and ears are extremely sensitive to vibration.

Without whiskers, a cat might bump into things in the dark.

It might not know if it fits through a gap. It would have to go slowly and carefully.

Whiskers tell a cat about things it can't easily see. Without them, a cat might find a dark room harder to cross. It might need to rely more on its eyes, ears and nose, and on its legs bumping into things.

A cat might also find gaps trickier. One veterinarian writes that if a cat's whiskers fit through an opening, the rest of the cat will probably fit too. Without whiskers, it might have to poke its head in and find out the hard way.

If whiskers were removed, a cat would lose one source of touch information about nearby objects, air movement and surface texture. It might move more cautiously in dim light, misjudge narrow gaps more often, and find it harder to locate things right in front of its mouth.

It would still have other senses: Britannica notes cats' acute hearing and a sense of smell with about 200 million odor sensors. How well a cat could compensate is an open question; these consequences are ideas based on what whiskers are known to do.

A whisker is like a long feeler. When it bends, the cat feels it.

The feeling part is deep in the skin, at the bottom of the whisker.

A whisker has no feeling along its length. All of its sensors are at the base, deep inside a pocket in the skin called a follicle. Whisker follicles go about three times deeper than the follicles of normal hairs, and bundles of nerves wait at the bottom.

When something bends a whisker, even a puff of air, the bend travels down to the base and presses on the sensor cells. They send a message to the brain: something is there!

Northwestern University researchers note that whiskers, like human hairs, have no sensors along their length; all the sensors sit in the follicle. In a 2021 study in PLoS Computational Biology, Mitra Hartmann's team built the first mechanical simulation of a whisker inside its follicle and found that contact makes the whisker form an S-shaped bend there, pushing or pulling on sensor cells.

Their model is based on data from rats, though Hartmann expects the findings to apply to mammals generally. Veterinarian Marty Becker notes that whisker follicles extend about three times deeper than ordinary hair follicles, with bundles of nerves at the base.

Never cut a cat's whiskers. The roots are very tender.

Many animals have whiskers, not just cats!

Real cats need their whiskers. Veterinarians say never to trim or pull them out, because the nerves at their roots are very sensitive and trimming can make a cat uncomfortable.

Cats are not the only animals with whiskers. Northwestern University scientists say most mammals use whiskers to explore the world by touch. Studying them may even help us understand how our own sense of touch works.

Veterinarian Marty Becker advises never trimming or pulling out a pet's whiskers, because the nerves at their roots are highly sensitive. Cats are crepuscular, most active at dawn and dusk, and Britannica calls their sensitive whiskers and hairs a “radar” vital for moving and hunting in low light.

Whisker research reaches beyond cats: most mammals use whiskers for touch, and the Northwestern team suggests that understanding how whiskers trigger sensor cells could offer insight into human touch.