Cats Eyes
What colour are cat's eyes when they glow in the dark? The common response would be green. The classic 'red-eyes' when humans are photographed by flash are well known, so can species be identified in the dark by their eye colour?
We received one report which stated:
We were driving up the hill toward Dechmont with my friend driving and me in the passenger seat with the Lamp. I had the window of the car down and was pointing the beam out toward a small wood to the right of the car. There were a number of 'contacts' where the light shines off eyes of livestock and other reflective surfaces, however, at one point the reflection of a pair of eyes showed green. This is the signature of a cat. (dogs and foxes are blue, sheep orange, rabbits red, horses white etc.).
Therefore I was surprised to receive sightings which stated "The eyes were orange like those on your index page." Was the cats eye animation misleading and should it be removed?
I happened to be re-reading The Beast of Exmoor Fact or Legend? by Trevor Beer and was very interested by the following passage on page 13
The only sightings I was prepared to discount absolutely were several stating 'Large, glowing green eyes seen at night'...
There is no way that glowing green eyes must refer to only cats. Dogs also show glowing green eyes at night, my own dog looking quite eerie as he walks up the garden path with just the eyes showing in this way
Thus it was probable that such sightings at or near sheep kills could have been the eyes of dogs.
The following photo, taken by Ben Willis, clearly shows that eyes colour dependes on how light is reflected. The cat's left eye (on the right of the picture) appears yellow-orange while its right eye appears blue.
After seeing the portion of the web-site regarding the identication
of various glowing eyes, I ran across this picture of our bobcat
and Prairie Dog together.
This provides a good example of how the glow will vary with certain
animals even at the same angle and distance.
Here, the color of the Prairie Dog is a distinct orange, while the
cat is green. Rodents, such as rabbits and rats will usually display
a color which varies form orange to red.
Whenever the two colors are seen together at night, there is a very good
chance
you are seeing both predator and prey. Fortunately these two formed
a truce several years ago.
Regards,
Ben Willis
George Markie also found the following article at http://www.vetinfo.com/.
Why do cats eyes glow in the dark?
Question: Can you tell me why cat's eyes glow in the dark.
Thank you for your help.
Stephanie
Answer: Stephanie-
Cat eyes don't actually glow in the dark. They do appear to be bright
green, most of the time, when they reflect light from another source. A way
of thinking about this is to imagine a mirror. It doesn't glow in the dark,
either -- but if you shine a light on it, the light is reflected back to
you and you see it as a light coming from the mirror. Reflectors like you
see at the end of driveways or on bicycles are another example of something
that doesn't actually glow in the dark but that shines brightly when it
reflects light.
If you go into a dark room without a light and look for your cat, you can't
find it by looking for its eyes. This proves that they don't have glow all
their own. It is pretty easy to find a cat in a dark room with a
flashlight, though. Even if you can't see the cat very well, you can see
the reflection from its eyes.
The portion of the cat's eyes that reflects light is the retina, or more
specifically, the tapetum of the retina. Most cats have green tapetal
reflections because they have colored retinas. Many Siamese cats do not
have pigmented (colored) retinas. When light shines in their eyes, the
reflection is red, because you see the blood vessels in the retina instead
of the green color that hides the blood vessels in other cats.
The advantage of having reflective retinas is that light that hits the
retina passes through the rods and cones (the part of the eye that allow
vision to occur) first. Some of it is absorbed and processed so that the
cat can see. The rest passes into the cells behind the eye. The reflective
layer in a cats eye reflects the light that would have been lost in this
manner back through the rods and cones, giving the cat a second opportunity
to use the light to see. This helps cats to see better in the dark than
animals that don't have a reflective tapetum.
I don't know for sure, but I think that people must not have much color in their retinas, which is probably what produces the "red eye" in photographs.
Some dogs have blue tapetums and so their eyes appear to have a blue
reflection when light shines on them.
I am not sure what the function of the different colors in the retina
really is. I will try to see if I can find some information on this for you.
I don't have any photographs that show the green reflection except in
textbooks.
I hope this helps you a little.
Mike Richards, DVM
2/10/2000
Scientists look at world through eyes of a cat
From the Press & Journal 13 th October 1999
Researchers have looked at the world through the eyes of a cat after wiring the animal's brain to a computer. The Californian scientists are the first humans ever to look through another creature's eyes, which they achieved by attaching electrodes into the part of the brain that processes vision. The other end of the wire was plugged into a computer, which transformed the impulses into images. The team from the University of California in Berkeley watched in amazement as blurred pictures began to appear, The Daily Telegraph reported. Scientists looked at a man's face and a woodland scene, but believe they were not seeing exactly as a cat would because they only took responses from 177 cells.
They think the animal's vision is actually more sharply focused than the experiment showed. The project, documented in the Journal of Neuroscience, was designed to help scientists understand how the senses send information to the brain. Molecular biologists Professor Garrett Stanley, Professor Yang Dang and Fei Li say their work could prove vital in future medical breakthroughs. They believe future teams will be able to fit replacement arms and legs - controlled directly by the brain - to people who lose their limbs in accidents.
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