Our eyes are some of the most complex structures in all of nature. The human eye can take in a million simultaneous impressions and can tell the difference between eight million different colours. On a clear, moonless night it can also detect a match being struck 50 miles away. As amazing as this is, there are other animals that have even better eyesight.
Cat Vision Vs. Human Vision
The biggest difference between human vision and cat vision is the retina. Cats have a high concentration of rod receptors and a low concentration of cone receptors. Humans have the opposite, which is why we can’t see as well at night but can detect colours better.
Cats can’t see fine detail or rich colour, but have a superior ability to see in the dark because of the high number of rods in their retina that are sensitive to dim light. As a result, cats can see using roughly one-sixth the amount light that people need.
It’s a common misconception that cats can’t see any colours, only shades of grey. Humans are known as trichromats, meaning they have three kinds of cones that allow them to see red, green, and blue. Cats are also thought to be trichromats, but not in the same way that humans are. A cat’s vision is similar to a human who is colour blind. They can see shades of blue and green, but reds and pinks can be confusing. These may appear more green, while purple can look like another shade of blue.
Human view vs. cat view
Dog Vision Vs. Human Vision
Dogs, contrary to popular belief, do not see the world in black-and-white. Their vision is actually most similar to cats in that they are basically red-green colour blind. Unlike cats, however, dogs have only two different cone types on their retina, providing them with what scientists call dichromatic vision. But there are other ways humans differ from dogs as well, including less sensitivity to both brightness and variations in shades of grey.
Dogs are also very nearsighted compared to humans. A special test, custom-made for dogs, puts them at around 20/75 vision, according to Psychology Today. This that what means a human could barely see at 75 feet is what a dog can just about make out at 20 feet. In fact, guide dogs have such poor vision that were they human, they would need guide dogs!
Horse Vision Vs. Human Vision
Horses, like dogs, cannot perceive the difference between red and green. They also have a similar rate of vision to a dog, at 20/60. Horses, like most flight animals, boast an impressive 350 degrees of monocular vision. This is due to the position of their eyes on the side of their head and allow them to see almost all the way behind themselves.
Horses have more rods than humans, a high proportion of rods to cones (about 20:1), as well as a tapetum lucidum, giving them superior night vision.
Eagle Vision Vs. Human Vision
Eagles and other birds of prey are the kings of the animal kingdom when it comes to visual acuity. Their retinas are not only packed with light-detecting cone cells, but they also have a much deeper fovea—a cone-rich structure in the back of the eye—which acts like a telephoto lens on a camera. Not only do they have a lens that changes shape—just like us.
Their cornea—the clear, outer portion of the eye—also has the ability to change shape to better focus on near and far objects. These characteristics are believed to give eagles visual acuity of 20/5, or 20/4.Thanks to this amazing vision, a buzzard can spot a rabbit flicking its ears from two miles away.
It seems to us that humans live in a bright, colourful world. But if we saw colours the same way an eagle sees them then we would see the world with even more brilliance; with bright colours rendered in an unbelievable array of shades.
Eagles can see colours more vividly than we do, they can even see ultraviolet light. Being able to see UV light gives them an ability to spot traces of urine left by prey.
Shark Vision Vs. Human Vision
Shark eyes come in all shapes and sizes, yet despite this, sharks and humans share many qualities when it comes to the eyes. Their structure is remarkably similar to ours. So much so, that their corneas are sometimes used in cornea replacement surgery in humans. You can in fact have shark vision!
Sharks do have some differences though. For instance, sharks can detect electric vibrations through their eyes. They also have a clear eyelid, which helps them see while simultaneously protecting their eyes. To see better in dark water, sharks have a layer of mirrored crystals behind their retina. These crystals give light another chance to be caught by the retina. These light-recycling crystals offer sharks 10 times the vision of humans in clear water.
Bug Vision Vs. Human Vision
Insects have more eyes than humans. Butterflies have four eyes, though most insects have five. Most spiders have eight eyes. Caterpillars have 12 eyes while houseflies have 4,000 lenses in each eye. A dragonfly’s eye contains about 30,000 lenses. With all these eyes, you’d think they were much better at seeing things than humans. Or are they just overcompensating?
The insect compound eye is like having lots of little eyes looking in different directions, but each little eye doesn’t see very well. The human eye can swivel, but it only looks in one direction at any given moment. The quality of its vision is much higher than that of a compound eye. SO if we are able to see the same thing as an insect, our eyes would see more details because the acuity of a human eye is about 100 times better than that of the best compound eye.
While an insect compound eye has the capability to see colour if it contains corresponding sensor cells, most insects can only see light and dark. A few, like bees, see more colours than humans, but they don’t have the additional qualities of vividness and shading.
Which animal has the best eyes?
So, many eyes don’t always mean better vision. In the animal kingdom, vision is dependent on environment and evolution. We’ve seen that some animals’ vision is highly tuned to their environments of the air or sea, while others supplement their poor vision with their better senses. Which is why your guide dog doesn’t have a guide dog of his own!