Recent scientific research has revealed how animals see the world around them and many possess dramatically different “sights” than humans. For instance, the brain of the dragonfly processes the images it sees so fast, it appears to be in slow motion and pigeons are capable of detecting more subtle color gradations than the most complex computer software. Below is a collection of comparisons between human and animal vision.
Amazingly, with their heads down while grazing, cows can almost see 360 degrees and can distinguish most colors except for blues. They are more adept with long wavelength colors such as red, orange, and yellow and much less adept with purples and grays. This gives their overall vision a reddish hue. In addition, cows have weak eye muscles and cannot focus quickly.
Horses see quite well except of course, for things that lie directly in front of them. Their eye placement however, lets them see near 350 degrees around them. They have dichromatic vision (two colors) and do perceive colors differently than humans though. For instance, red colors will appear more green to a horse.
Monkeys see much as humans do but with a variety of color-blindness variations. Many tend to have difficulty seeing reds and greens.
Cats and dogs
Cats and dogs rely more on smell and sound and hence, are mostly color blind (dogs can detect a bit of yellow and blue and cats can tell the difference between red, blue and yellow). With a reflective layer behind the retina, they do however, have excellent night vision and much better depth perception than humans.
Snakes have two sets of eyes – one that sees color like humans do and another set that detects heat. That means yes, they can even see through walls. Most snakes focus by moving the lens back and forth in relation to the retina, but some focus by stretching the lens. Combine this with an excellent sense of smells and the ability to detect minute ground vibrations and you have an excellent ability to hunt prey.
Sharks are mostly color blind but do pick up light better than humans making their vision more sensitive, but less acute than humans.
Many marine animals, such as Sea Turtles, have photoreceptors that contain tiny red oil droplets which obstruct shorter light wavelengths. As such, they can easily see red, orange, and yellow but cannot see longer wavelength colors such as green, blue, or violet.