Five senses of the cat

A small and highly specialised predator, the cat has very fine organs of sense. Her sight is six times sharper than a person’s, and she tells shades of colour apart perfectly well.

For her chief “profession” — hunting in half-light, at dusk — the cat is exceptionally well equipped. She can catch the faintest gleam of light. A cat’s eye is built on the principle of the aperture in a camera: the pupils send only as much light to the retina as is needed to “light the picture”. In weak light a cat’s pupils are large and round; in bright sunshine they narrow to thin slits.

A cat’s eye has a third eyelid, set in the inner corner. For an owner an enlarged third eyelid is a warning sign, since it can be a consequence of illness — severe emaciation, for instance.

To find her way about on her nocturnal outings the cat uses touch and a fine ear. Cats take in sound frequencies in the range from 50 to 60 kHz. A dog responds to sound at about 40 kHz; a person can catch sound at 20 kHz.

A cat’s sensitivity to loudness is three times greater than ours! (If we are listening to loud music, or the television is blaring in the room, the cat should be given the chance to go into another room.)

The cat’s sense of smell, though considerably finer than ours, is a lesser thing than the dog’s: the dog is the greater specialist here, hunting as it does chiefly by nose. For a cat, smell matters in another field — contact and the exchange of information with others. What people do with words and gestures, cats do by leaving marks and keeping watch on the smell of them. Toms carry on this particular exchange of courtesies in a very characteristic way. They leave a scented spray of urine and squirt the places that smell of their rivals and of the toms living on the same ground, setting about it with enviable steadiness and persistence.

Cats leave far less pungent smells with the scent glands in the pads of their paws. What thrills a tom like Chanel No 5 is something we cannot smell at all. A tom rubs his neck and cheeks, with an air of complete rapture, over the place where the object of his affections has walked, and so shows his hidden sexual or belligerent mood. These movements are not the same as the way cats rub a cheek against a person: when a cat is dealing with a human being, rubbing is how she shows her liking.

The smell of certain plants — mint and thyme, for instance — has a powerfully intoxicating effect on cats. Elder intoxicates them too.

A cat’s tactile hairs are like sensitive aerials. By means of them she registers the information she receives and sends it to her brain: a natural feline oscillograph at work. In this way a cat surveys her hunting ground with unerring reliability.

Watch a cat and you will see how thoroughly she sniffs at and examines everything, her prey above all, with her vibrissae — her whiskers. That is how she gets the information she needs.

A cat’s long, splendid vibrissae catch the eye. Touch is also served by the fine, delicate tufts of hair above the eyes, on the cheeks, on the chin and near the pads of the front paws. Vibrissae and tactile hairs do not come out with the coat during the hormonally driven moults; they are lost singly and are constantly replaced. On no account may vibrissae be trimmed!

Mother cats sometimes tire of their kittens’ vibrissae and bite the little whiskers off. Whether this has any other sense to it is not reliably known. Perhaps the cat means to keep some over-inquisitive kitten from leaving the “nest” too early. Five or six months pass before the kitten grows a proper whisker again.

On the cat’s sense of taste, scientific articles usually have just the one classic statement: “a cat can distinguish sweet, bitter and salt”.

A cat’s tongue, like ours, is covered with taste papillae, and she is exceptionally particular about the taste and the texture of the food she is offered. She is the most pedantic customer the pet food industry has. A cat is usually offered ten lines of flavour, of which, having tried them, she will accept — if she accepts any — two or three.

On the upper surface of the tongue are small horny hooks, which human skin feels as rough emery paper. A few touches of that rasp of a tongue are enough to redden our skin. The horny hooks clean and smooth the cat’s coat, and help her deal with a large piece of meat by scraping the fibres off it.

A cat does not lap water with a flat tongue: she shapes it into a little channel and, with quick movements, catches the liquid up and sends it into her mouth.

Eyesight

A cat’s sight is six times sharper than a person’s. In bright sunshine the pupils narrow to thin chinks; in weak light or in darkness they are large and round. A cat makes use of the faintest glimmer of light, and her twilight vision is very keen. For a long time it was held that cats see everything in grey. Over the last decade, after a great many experiments, scientists have concluded that a cat distinguishes six basic colours and twenty-five shades of grey — and that the favourite colour of most of them is red.

Acoustic stimuli are taken in not only by the ears but through the nerve cells of the eyes, which can hear (!) and pass the signals to the brain.

Here is a tiny ant, crawling along six metres away. A human eye cannot make it out. But nothing escapes a cat roaming about the garden. Her sight is developed fantastically well. A single glance and she has “taken in” everything that moves. She sees at one and the same time the bird hopping among the branches of a bush on the right and the bumblebee settling on a flower on the left, and that same ant a few metres off as well. It has been tested: if her mistress walks past a hundred metres away, the cat will know her by her outline alone. A cat’s eyes, unfathomable and mysterious, are simply a marvel. They shine in the dark because the small nerve endings, the rods in the retina, respond particularly to a small flux of light and so “clear up” the image. At dusk a cat sees six times better than a person. The pupil, changing its size, regulates the light coming in. It is like a “slit shutter”, which in bright sunshine draws together into a narrow vertical chink.

The cat is the owner of enormous eyes. Of all domestic animals the cat has the largest eyes in proportion to the size of her own body; and if the size of the eye in relation to the body were the same in a human being as it is in a cat, the human eye would be twenty centimetres across!

The sense of smell

A cat cannot exist without the world of smells. Deprived of sight and hearing she will manage to adapt to life; deprived of scent, never — she is doomed.

Besides the nose, a cat has an additional organ of smell, Jacobson’s organ: two narrow canals that begin immediately behind the upper incisors and continue in the palate as the canals of Stensen. To use it the animal raises its upper lip and opens its mouth a little, drawing air in through the mouth to the nose, as though tasting the air. The functions of Jacobson’s organ have still not been studied, and there are several versions of what it is for.

First, it is thought that the organ is adapted to taking in the smell of food and adds to the information the organ of smell has already supplied — that is, a cat has a mouth sense of smell as well as a nasal one.

By another version it serves to take in sexual pheromones, and so is used in finding a mate.

Supporters of a third version hold that this organ has the power to register the slightest changes in the chemical make-up of the air, and set it down to the “sixth sense” that lets a cat feel such natural upheavals as an earthquake or a volcanic eruption coming.

The sense of touch

Even in complete darkness and silence, when a cat cannot find her way by eye and ear, she is not helpless: she has tactile hairs, the vibrissae. They act as highly sensitive aerials and are of inestimable help to a cat in finding her way about at close quarters. They are set above the eyes, on the upper lip, on the cheeks, on the chin and on the underside of the front paws. These hairs are very stiff and thick, their roots lie in the skin far deeper than those of the other hairs, and they are richly innervated — that is, an enormous number of nerve endings runs into the root of the hair. Vibrissae do not come out during the moult.

The vibrissae of the face are the most developed of all, and are usually called the whiskers. They are set above the upper lip in four horizontal rows, and the most powerful and longest of them are in the second and third rows.

A cat’s whiskers are not an ornament: they do work that is vital to her. Through them the animal gets information of every kind. Whiskers answer with incredible delicacy to the slightest stimulus and catch movements of the air; they need not even touch an object, it being enough to pick up the currents of air that arise as the cat comes near an obstacle. The least movement of the tip of the hair passes to the root, where sensitive nerve endings take it up and inform the brain at once.

Those magnificent whiskers play no small part in the expression of the face. A cat can push them forward in pleasant expectation of a caress, or flatten them against her muzzle in an angry snarl.

Hearing

Besides having far finer hearing than we do, a cat also reads “mouse language” admirably. Mice communicate by sound signals in the region of 40 kHz. Cats pick up these “mouse conversations” without difficulty and always have precise information about when a mouse means to leave its hole. The figures given are these: the lower limit of the range of hearing is 30 Hz and the upper 60-65 kHz, and in ten-day-old kittens the upper boundary is higher still — 100 kHz.

Cats have magnificent hearing. Nature has given their ears remarkable powers: out of all the everyday noises they can filter the ones the cat herself counts as important — the sound of her owner’s step, for instance. And in their eyes, as has already been said, there are nerve cells that pass noises we cannot hear to the brain. What is to us the “silence of nature” is to a cat a whole concert of rustles, whispers, hummings and cracklings; twenty-seven muscles tune the two ears to any direction, independently of one another. On the edge of the ear there is a small fold of skin, and it is supposed that this is nothing other than a resonator.

A cat’s hearing, fine as it is, is selective: her ears respond only to sounds that hold some interest for her. If a sound is loud but familiar, she will not so much as wake; but if it is unfamiliar, however quiet, she will be on the alert at once, listening.

Taste

The organs of taste distinguish sour, salt, sweet and bitter substances. Cats make out bitter and salt substances well, and sweet ones less well. This is in all probability because the live prey of the wild ancestors of the domestic cat had the slightly bitter, slightly salt taste of blood and meat.

Organs of sense and Cat’s abilities

The ability to find her way home. A cat’s eye takes in not only optical stimuli over a wide range but responds to acoustic signals as well. Cats take in a precise picture in sound of their surroundings. They “register” various noises — the sound of a bell, factory hooters, the voices of animals, the noise of work in a farmyard and so on — and judge their distance, their loudness and the angle the sound comes from, taking in this optical and acoustic picture as their home surroundings. A cat lost in the countryside will try to catch the noises that stand out most, the rustlings of her home that she knows well.