The Remarkable Physiology Of The Domestic Cat.
Cats are amazing creatures with athletic abilities far beyond anything a human could manage, as anyone who’s ever tried to catch a mouse can appreciate. Cats can jump and climb and squeeze through tiny spaces, and generally navigate their way around a three-dimensional world with much greater ease and dexterity than humans and many other mammals. In order to do this, they have some very special physical features which make them supremely well-adapted to early morning escapades and late evening prowling.
The eyes of a cat are relatively large compared to those of other mammals. With their dilating irises, which appear to wax and wane like the moon, and their reflective ‘glow in the dark’ properties, they have a magical aspect which has fascinated humans for centuries. Even when we’re armed with the science explaining exactly how the feline eye operates, it is difficult to imagine quite how cats experience their visual world because it differs in some crucial way tour own.
Cats have a wide field of vision than humans – call it widescreen effect – which gives them more peripheral vision than us, so they can get a proper look at something that we might just glimpse out of the corner of our eye, if we’re lucky. The cat’s eye also makes the most out of every scrap of light, so their night vision is much better than ours. But there is a trade-off. Cats are not as good as us at focusing on close object – so if it’s right under their nose, it’s just a blur.
Nor do cats have much time for color. They don’t actually see in black and white, but they only have two types of cones (cells in the retina which are sensitive to color), one green-sensitive and one blue-sensitive. Humans have three types of cones, so we can distinguish a greater range of colors. In any case, cats are not wired to give much importance to color, so everything else about an object – its size, shape, movement and the amount of light it gives off – gets much more attention from the feline brain.
One feature the cat has that we manage without is something called the nictitating membrane, which is a kind of third, semi-transparent eyelid. Common in birds and reptiles, this extra feature gives the cat added protection and keeps the eye moist, so they don’t need to blink as much as we do.
Kept In The Dark.
Contrary to popular belief, cats can’t actually see in the dark. That’s to say, if it’s absolutely pitch black, a cat is just as likely to stumble over a discarded cat toy as we are. But their vision in dim light is many times better than ours – ideal for a spot of hunting at dusk. Their large, elliptical pupils can open very wide to allow in as much light as possible. Cats also have a reflective layer of cells behind the retina, called the tapetum lucidum, which acts as a mirror and reflects light onto the retina, boosting night vision and creating a glow-in-the-dark look in dim light (and making cats frustrating subjects of flash photography).
Felines share this characteristic with other crepuscular animals (those that are active primarily at dawn and dusk), but it was a cat that inspired a road safety innovation that has saved many lives. In 1933, Percy Shaw, from West Yorkshire in Britain, was driving along a dark stretch of road when he saw a pair of green lights. It turned out to be a cat’s eyes reflecting in his headlights. Struck by inspiration, Shaw went home and developed a reflective rod stud, which he called the Catseye.
Why Cats Don’t Need Sunglasses.
People wear shades to shield their eyes from the glare of the sun, but cats have a superior design feature in their eyes which makes these accessories unnecessary: pupils which contract to a vertical slit. In the wild, cat survival depends on the ability to see as much as possible in dim light. But cats’ eyes are also extremely well-adapted to controlling how much light hits the eye in bright sunlight. The vertical slit of the pupil combined with the horizontal line of the eyelids gives the cat maximum control over the light entering the eye.
Five Remarkable Facts Relating To Cats.
Are your cat’s eyes “hard”, round and focused or “soft”, almond-shaped and relaxed? Are they making eye contact (confident and challenging) or averting their gaze (avoiding confrontation)?
- Fearful cats may look more to the left and relaxed cats more to the right
- Adrenaline dilates the pupils and increases blink rate
- The pupils constrict when a cat is relaxed (or in bright light)
- Slow blinking shows contentment
- Fully closed eyes suggest they are asleep, but may also be a response to sensory hyper stimulation, anxiety or pain.