Feline Sense and Scents-ability: Part 4: Sight

SIGHT

Despite those huge, luminous eyes that sometimes seem to glow in the dark, a cat’s sense of sight is probably its least important sense next to taste! Cats can thrive with only one eye or even no eyes! Without sight, a cat relies on its sense of touch and hearing to map out the world, just like a human would.

The glow that you see in your cat’s eyes is light reflecting off a membrane lining the retina that collects and amplifies light called the tapetum lucidum. Because of this membrane, cats can see in as little as 1/6^th the light that humans need to see – but they still can’t see in complete darkness. Cats have many more rod light receptors than cone light receptors in their retina. Rod receptors are good at sensing motion and seeing in low-light conditions. Cones are the light receptors that sense color variation. What this means is that in order to see so well in so little light, cats sacrifice some clarity of vision, but they are much more skilled at sensing tiny motions, have extremely well-developed depth perception and much more acute low-light vision. They also have 200 degrees of visual field vs. human 180 degrees but their field of binocular vision is slightly narrower than ours. What a human can see clearly at 100 feet, a cat can only see clearly as far as 20 feet.

People often wonder if cats can see colors. They can, but their perception of color is much more limited than ours. They have dichromatic vision, meaning that they have two types of cone light receptors in their eyes - yellow/green and blue. Humans have trichromatic vision, meaning that in addition to the color receptors that cats have, we also have receptors that sense the color red. Cats can tell the difference between green, blue and yellow, but probably have difficulty distinguishing between red and green. Cats are able to distinguish between colors at the blue end of the spectrum (long wavelengths) better than between colors near the red end of the spectrum (short wavelengths).

Photo interpretation by Nicolay Lamm (http://www.wired.com/2013/10/cats-eye-view/)

While color and field of vision are limited, a cat seems to be exquisitely sensitive to sensing motion, or changes within the field of vision. It is thought by some that instead of seeing fluid motion, cats may see a "stop-motion" view of the world, giving their brain time to compare each "scene" to the one before and process minute differences between each image.

Cat Flip Book from matthieu scanlon on Vimeo.

A cat’s eyes can indicate a lot about its mood – the cat’s pupils dilate up to five times their normal size when it is frightened or threatened, or about to pounce. When cats are content, they squint their eyes.

This alert kitten's dilated eyes mean it is likely going to pounce

This cat's dilated eyes mean it is ready for a fight, with ears tucked back protectively

Cats have a third eyelid or nictitating membrane that closes across the eye from the inner corner. This third eyelid is whitish in color and is usually retracted when the cat is awake. When a cat is ill, the third eyelid often becomes visible as it relaxes and covers part of the eye. Sometimes, this is due to an eye infection or injury, but it can also mean that the cat doesn't feel well in other ways.

Besides eye disorders, third eyelid elevation can also commonly be caused by fever and vestibular (inner ear) problems

Because cats don’t see well close up, it seems that cat food and toys that come in fun shapes and colors are designed more for humans enjoyment than for cats – smell, sound and motion are much more fun to them.Instead of using sight for close-up encounters, cats point their whiskers forward and use the sense of touch to guide them.

So, to better understand your cat, instead of taking a “cat’s eye view” of the world, perhaps it would be better to take a sniff and a listen, instead?

Feline Sense and Scents-ability: Part 3: Touch

TOUCH

Cats have a highly developed sense of touch. Most obviously, they have 24 vibrissae, or whiskers, grouped in 4 sets on each side of the nose. The whiskers on the face are called mystacials and the top rows can move independently from the lower rows. The whiskers above the eyebrows are called superciliary whiskers. There are also whiskers on the backs of a cat’s front legs associated with the accessory carpal gland. All these thick hairs, about 2 times thicker than the rest of a cat’s fur, and rooted 3 times deeper in the skin, are surrounded at the base by bundles of nerve receptors that send messages to a special area of the brain called the barrel cortex. There, the nerve signals create a 3-D map of the spatial environment based on a cat’s touch in a way very similar to the visual cortex’s map of the visual environment.

Cats’ whiskers also help them judge distances – from planning and executing aerial acrobatics to deciding if they will fit through small openings, and they are also a measure of a cat’s mood. Whiskers that are perked forward and spread widely apart communicate that a cat is alert and interested in the environment, possibly aggressive. Whiskers that are relaxed and positioned slightly downward indicate that the cat is feeling passive. Whiskers that are plastered back against the cat’s face indicate anger.

Cats can’t see directly underneath their noses, but they can spread their whiskers forward around their nose to form a “basket” that identifies the location of objects the cat can’t see – such as that tasty treat you just offered her. Subtle changes in air movement that move the whiskers as little as 1/200^th the width of a human hair can also help alert cats to prey they can’t see.

Rexes and Sphynx breeds tend to have very short, curly whiskers

Avoid cutting your cat’s whiskers, as they are a valuable part of how a cat “sees” the world. The whiskers of most cats (Rexes and Sphynxes excluded) are as wide as their body, so any opening that they can pass their whiskers through without resistance is an opening they can fit their body through. Cats with trimmed whiskers, or cats that are overweight run the risk of getting stuck.

Interestingly, it seems that many cats prefer to eat off of a flat or very wide, shallow dish instead of a deep, high-sided bowl because the flat dish does not interfere with their whiskers. This seems to be especially true of cats that are not feeling well.

The places on your cat's body that are most touch-sensitive are the face and the front paws. These parts of the body are your cat’s most important hunting tools.

Also, cats tend to develop surface texture preferences for everything – from litter to scratching posts, to beds. Pay careful attention to what your cat tells you – if she is not using the litter box, perhaps she doesn’t like the feel of wheat litter. If she likes to scratch on your nylon duffel bag instead of her carpet-covered scratching post, perhaps a sisal-rope post that has a little rougher texture to it would be a welcome change.

In addition to the ability to sense distance, movement and texture, cats are born with a highly developed sense of temperature sense. In the first 10 to 14 days of a kitten's life, they learn to navigate by differences in temperature. Heat receptors at the tip of a kitten’s nose detects variation in temperature as small as 0.9 degrees F, which helps the sightless infant navigate towards its mother and siblings.

Feline Sense and Scents-ability: Part 1: Hearing

Cat Ear from fantasystock.deviantart.com

Feline Sense and Scents-ability

Even though cats have the same five senses humans do, their perception of the world is much different. Sometimes, trying to understand a cat’s point of view can help shed some light on problems you may be having with your cat.

HEARING

Feline hearing is functionally the same as human hearing. The pinna, or outer portion of the ear, collects sound waves and translates them down the ear canal. In humans, the ear canal is a straight shot to the ear drum, while cats have a vertical canal connected to a horizontal canal in an “L” shape from the top of the head, straight down and then turning inward. Once the sound waves have rounded the corner of the ear canal, they cause the eardrum to vibrate, stimulating the ossicles of the middle ear (tiny bones called the malleus, incus and stapes - otherwise known as the hammer, anvil and stirrup). These ossicles transmit the sound waves to the cochlea.

Cat ear anatomy

The cochlea is a fluid-filled structure in the middle ear. The sound waves are translated to fluid waves in the cochlea that are then sensed by nerves connected to fine hairs that float in the fluid and is then sent on to the brain for interpretation. This is the area that a human “cochlear implant” stimulates to help correct hearing loss. The feline cochlea has 3 complete turns while the human cochlea only has 2.75 turns. They have 10,000 more auditory nerves than humans. Near the cochlea is another fluid- and carbonate crystal-filled structure called the vestibular apparatus that is in charge of balance.

Cats are exquisitely adept at locating prey. They can distinguish between two different sound sources 8 cm apart (shorter than the length of an iPhone) at 2 yards and 40cm apart (about 1 foot, or a little longer than 3 iPhones) at 20 yards. They can hear a rustling mouse 20-30 yards away. They can hear 10 distinct octaves of notes vs. humans’ 8.5 octaves. They even hear one octave above their canine counterparts.

Chart courtesy of www.watchingtheworldwakeup.blogspot.com

There are 4 sets of muscles that control the motion of the cat’s external ear flap, or pinna, and allow it to rotate 180 degrees to catch a sound and orient on it. You can use this information to make playtime more interesting for your cat. Make “hide and seek” with toys more challenging by using quieter, less obvious “prey”. Test your cat’s auditory awareness with a tiny crinkle from a crinkle-toy. See if they notice.  

Even though you think they can’t hear you, don’t yell at your cat! He can hear you, he just isn’t listening to you.

When your cat is sleeping it is still attentively listening, scanning for audible information, which is why your “soundly sleeping cat” is standing right at your feet the second you open a can of food.