Different animals can see different kinds of colour from a broad range of spectrums. Some see very little colour, while creatures such as bees and butterflies see more than us as humans.
Cats and dogs are colour blind
To see in full colour as we know it, humans use three cones – red, blue and green. However cats and dogs only have blue and green cones. This means they have a much more muted perception of colour, which is akin to colour blindness in humans.
Cats' two color-detecting cones let them see blue-violet and yellow-green wavelengths of light, but not red-orange. So, similar to dogs, cats mainly see things in shades of yellow, gray, and blue tinges, but some researchers think that cats may also notice some shades of green.
Dogs' eyes only have 2 types of cones (just 20 percent of the cones in human eyes). Because of this, a dog's color spectrum is limited to shades of gray, brown, yellow and blue. This is called dichromatic vision, which is similar to humans who experience red-green color blindness.
Birds have exceptionally keen vision. In fact, their ability to see color is far superior to humans' color vision in several ways. While humans have three color-detecting cones in their eyes — to see red, green and blue shades — birds have a fourth cone that enables them to see ultraviolet (UV) light.
Eagles – Best Eyes in the Animal Kingdom
To put that into perspective, an eagle has the visual acuity of 20/5 – meaning that it can see at 20 feet what a human with 20/20 vision would need to be 5 feet away from to see. By this standard, an eagle's visual acuity is 4 times stronger than ours.
Horses can see only two of the visible wavelengths in the light spectrum because they have only blue-sensitive cone cells and yellow-sensitive cone cells. Thus, they see blue, green, and variations of the two colors, but do not see red or shades of red.
In order to design an environment that is comfortable for animals, choose light color schemes that are centered on the blue, green, or violet end of the spectrum, or a scheme that is inspired by nature.
Cat behavior researcher John Bradshaw of the University of Bristol says that cats probably see us as especially clumsy — which most of us are, by cat standards. However, despite legions of Internet memes, they do not see us as foolish inferiors.
Cats are a bit better at near vision. But both dogs and cats rely more on motion rather than focus, and are rather farsighted, an evolutionary side effect of scanning the distance for prey. A dog can detect strong hand signals from as far away as a mile.
Cats have good night-vision
However, they do have better vision than we do in low light conditions, such as on a moonlit night. This is because they have more receptors in their eyes called rods, which are sensitive to light, helping them to see six to eight times better than we can in the dark.
According to the book "Improving Animal Welfare" by Temple Grandin, cattle lack the red retina receptor and can only see yellow, green, blue, and violet colors. Color vision in mammals is accomplished by a collection of cone cells on the back of the eye (the retina).
Prey animals identify predators by smell and sight—including their view of eye position. One look at a human face, and the evolutionary equine brain knows we are predators. Because horses see us as natural predators, human eye contact has a warning effect.
Usually, horses trying to rub their face on a person are itchy or the seeking connection of mutual grooming. Good grooming can help meet both needs.
When a horse looks away, either with his eyes or whole head and neck, it is a calming cue. He uses a signal like this when he feels pressured and wants the rider to know he senses the person's agitation or aggression, but that person can calm down because he is no threat to the human.
Leech: Leech is an annelid. Leech's external and internal segmentation do not correspond to each other. If the internal body is examined, it can be seen that the body is divided into 32 parts or segments which have their own corresponding brain.
If you encounter an aggressive lion, stare him down. But not a leopard; avoid his gaze at all costs. In both cases, back away slowly; don't run.
What ethnicity has the best vision? As a group, the Aborigines have significantly better visual acuity than the Europeans. This was true for both monocular and binocular vision. Some Aborigines have acuities below the previous postulated threshold levels.
We see our world in a huge variety of colour. However, there are other “colours” that our eyes can't see, beyond red and violet, they are: infrared and ultraviolet. Comparing these pictures, taken in these three “types of light”, the rainbow appears to extend far beyond the visible light.
We have three different kinds of cones in our eyes, called red, green and blue that make human color vision possible. The goldfish has four kinds of cones: red, green, blue and ultraviolet. Other fish have different numbers and kinds of cones meaning that they have the capability of seeing in color.
For those who might be worried, Magpies have very good eyesight and are more intelligent than many a motorist. The spikes are easily seen by magpies and consequently they abort strikes and stand-off by 2 or more metres.