Animals don’t usually have bad eyesight in the same way that humans do. While there are rare cases of animals with poorer eyesight than other members of their species, usually when animals have poor vision, it happens pretty consistently across their entire species.
It might come as a surprise to some that there are actually a number of animals with bad eyesight and all of them found a way to adapt in some other way for survival.
For example, its hypothesized that nocturnal animals like the armadillo and deep sea fish have bad eyesight during daylight hours because their eyes are better suited for nighttime vision, while animals like domesticated cattle and rhinoceros have eyes on either side of their head that gives them blind spots in their vision.
Below, we’ll take a closer look at different animals with bad eyesight, including the reason that their vision is so bad and the evolutionary traits they’ve adapted to help their species survive instead.
We’ve all heard the common phrase, “blind as a bat”. When it comes down to it though, bats aren’t completely blind. Instead, their eyesight is better adapted to flying around caves at night.
During the daytime, the bright lights are overwhelming to a bat’s sensitive eyes. This renders them essentially blind in bright lights.
Additionally, while their eyes work somewhat in caves, they still don’t have eyesight good enough to spot insects from across a cave. Instead, they rely on echolocation to hunt. Basically, they send out sound waves and when these waves bounce back, they’re able to locate their food.
A rhinoceros is one of those animals you don’t want to come face-to-face with in the wild, especially if it sees you as a threat. Rhinos have large horns and are known to charge at high speeds. Pair this with their impressive size and it’s really not something you want charging toward you.
According to the World Wildlife Fund, rhinos can only see about 100 feet away. At this distance, the mighty rhinoceros can’t distinguish between a human and a tree. This may be one of the reasons they are so quick to charge at humans- we smell foreign to them and they cannot tell if we’re dangerous.
Rhinoceros have poor vision because of the anatomy of their eyes. They’re located on opposite sides of the rhino’s head, so they can’t see well in front of them. They also don’t have binocular vision like humans do, so their fields of vision don’t overlap and they do not have good depth perception.
While a rhinoceros might not have the best vision, they do have great hearing and a fantastic sense of smell. Rhinos can smell humans from as far as 2,600 feet.
Moles are well-known for their unattractive appearance and it’s not uncommon for people to think they are blind, too. However, moles are one of those animals with poor vision– not one of those animals that don’t see at all.
Scientists believe moles are both nearsighted and colorblind. That being said, their eyes do respond quickly to light changes that happen in their habitat.
In fact, mole eyes are incredibly sensitive and pick up light changes without them opening their eyes at all. This is important for sensing the season changes and keeping circadian rhythms. Season changes are important because moles only mate in the springtime.
As a result, moles rely on their strong sense of smell to find insects and food. Some species have even had flaps grow over their eyes and it hasn’t affected their ability to sense light or find food.
Domesticated cattle are actually associated with having good vision and being fairly intelligent. Their eyes are positioned pretty far up on their head, which lets them see over grass and shrubs and keep their eye out for threats while they are grazing.
When it comes down to it, however, male cattle have trouble seeing because their eyes generally stay focused on the ground. They have great eyesight, but because they focus on the ground right in front of them, bulls tend to have limited visibility when it comes to the big picture.
A bull’s tendency to look at the ground is one of the reasons matadors shake capes to get the bull’s attention. According to an episode of Mythbusters, however, bulls don’t actually charge toward the color red. They charge toward whatever flag is moving the most, regardless of color.
Deep Sea Fish
There is a lot that we still don’t know about ocean animals and all their unique features, especially when you consider that so much of the world is covered in water and so little of it has been explored.
One of the things that has been learned so far, however, is that animals that dwell toward the darker parts of the ocean floor usually have eyesight that lets them see in darker conditions.
This means that if these animals were to travel upwards, their sensitivity to light is likely to make seeing more difficult. Deep sea fish are different from sea animals that dwell closer to the surface because animals that live closer to the surface have eyes that are adapted to their environment in other ways.
In addition to being better suited for darker conditions, researchers published a study from Lund University in 2004 that identified different parts of the fish eye and how it affects their vision. Something notable about deep sea fish is that their eyes are typically larger to notice the differences in shadows and lights at this depth.
Additionally, deep sea fish have retinas that focus horizontally. This lets them take in the sea floor all around them, rather than focusing on what is above or below.
You would think that an animal that has eyes as large as a horse would have excellent vision. And, while horses do have excellent vision when it comes to scoping out what is going on around them and looking for predators on the horizon, horses actually struggle when it comes to seeing close up.
If you’ve ever spent time around horses, you might notice that they are perceptive of their environment. When they are spooked or sense something on the horizon, their nostrils flare, their ears perk up, and their eyes get wide.
The reason for these changes is that a horse actually has a hard time focusing on details in their vision. They open their eyes to try and focus and they open up their ears and nose to use their other senses to give them clues about what is going on.
Additionally, horses are one of those few animals that have different acuity, or strengths and weaknesses in their vision. It’s believed that about 23% of horses are nearsighted and about 43% are farsighted. Additionally, the average horse needs to be about 50% closer to an object to see details than a human does.
Snakes are traditionally burrowing creatures, so with the exception of the few species that have adapted to daytime hunting, they generally have poor daytime vision. This allows them to see outlines and movement, but they struggle to see details.
Their inability to focus and see details is one of the reasons that snakes like pit vipers and a few others rely on their ability to sense heat to find prey. These snakes won’t eat dead mice or rodents for this reason.
One of the reasons for a snake’s poor vision is that they have a scale that grows over its eyes. This scale does serve a purpose, as it keeps dirt and debris out when they burrow.
Snakes are one of the few animals that can see with their eyes closed because of this scale, too. This essentially works as a type of eyelid that the snake sheds as it grows. Right before a shed is when a snake’s vision is worst- fluid builds up behind the scale over its eye that the snake struggles to see through. This is one of the reasons they are less likely to eat right before a shed.
Mexican Tetra Fish
Tetra fish are a popular pet store choice. They are known for their bright colors and are found in different tropical areas all over the world.
Interestingly, researchers learned in the early 1900s of the poor vision of the Mexican tetra fish. There is a genetic mutation in the species caused by the gene rhodopsin.
Rhodopsin is responsible for helping the retina detect light using rod cells in the eye. This specific mutation has made the rod cells in the eye dysfunctional, so the fish cannot distinguish between light and dark.
As animals adapt over time as a result of climate change and other factors, species like the Mexican tetra fish may mutate.
One such species is the Mexican cavefish, which possesses the same gene and is actually blind. These fish are born blind because their body actually stops blood flow to the eyes during embryonic development.
Armadillos are a pretty impressive creature. They can smell insects that are burrowed into the ground and they even jump when startled- as high as 1 meter into the air. Where the armadillo falls short, however, is its vision.
Armadillos no longer have cones in their eyes that detect colors. This means that the picture they get of the world around them is often fuzzy and colorless. Fortunately, their strong sense of smell gives them an evolutionary edge.
Additionally, armadillos lack key muscles in their eyes that allow them to focus on something. Animals like sloths and anteaters also lack this muscle, so it’s believed that they have poor vision for this reason as well.
Interestingly, understanding how an armadillo’s eyes work could bring scientists closer to understanding colorblindness and other vision problems in humans.
Armadillos possess several cones in their eyes similar to the cones found in other mammals. However, armadillos have poor eyesight because these cones became nonfunctional at some point in the armadillo’s evolution.
Mice, Rats, and Other Nocturnal Animals
Researchers also believe that mice and rats tend to have poor vision in daytime settings, which might explain why they are so likely to burrow and come out to look for food at night.
While rodents do possess the rods and cones in their eye to detect light, they are better suited to low-light conditions so they can see shifting shadows and movement at night.
You’ll find this is true of a lot of nocturnal animals. When animal eyes are adapted in a way that lets them see in the dark, their eyes are often too sensitive for them to adjust to daytime lighting. Many of them are almost blind (if not completely) during the daytime as a result.
Do Animals Have Poor Vision Like Humans?
Humans have eyesight all over the spectrum. Unlike animals, however, humans have options like glasses, contacts, or corrective eye surgery as an option to improve vision and make it possible to do the things they need to do on a daily basis.
Some animals (like the ones mentioned on this list) naturally have bad vision. However, they often have some other evolutionary trait or heightened sense that lets them survive. The various animals across their species also have the same challenges.
Incidences of animals that have poorer vision than other members of their species are rare. When it does happen, these animals have a harder time finding food and hiding from predators. This means they are less likely to reproduce and less likely to pass down bad vision genes, so poor vision dies out with time.
The exception to this are animals that are more domesticated, like dogs. Dogs rely on their humans for survival, so there isn’t that same competition that exists in the wild. They are also more likely to be bred based on factors like how cute people find them, rather than their hunting abilities or eyesight.
However, even in the human world, researchers don’t really believe that poor vision is something that existed in ancient times. This study talks about how the environment has impacted human vision over time.
How Do Scientists Test Animals With Bad Eyesight?
When ophthalmologists test a person’s eyesight, they do things like have them read a chart with letters of different sizes and tell them when they see a dot flashing in their field of vision. Animals, however, do not have the same verbal abilities that would let them communicate their ability to see something (or not see something) from far away.
There are a lot of different ways that scientists can test animal vision. With animals that can be trained, it’s not uncommon for researchers to train them to react to a visual cue, like a ball. Then, they test their ability to see that visual cue from different distances.
For other animals, scientists might shine a light in their eye to see how fast it reacts. They might also study the cones of light in an animal’s eye. These cones pick up certain colors, so this helps them know which animals can see color.
So, what animals have bad eyesight? Some animals like horses have poor vision close up but not far away, while animals like bulls have great vision but struggle to see because they focus on the ground in front of them instead of looking at the horizon.
With animals like bats and deep sea fish, the difficulty of seeing during the day is likely from the way their eyes have adapted to see in dark areas like caves or the bottom of the ocean. Often, animals that don’t have great vision make up for it in other ways- like the way a rhino has a great sense of smell and bats use echolocation for hunting.
While researchers have to use unique tests to figure out what animals can and cannot see, including how well they can see and the color, understanding animal eyesight has also brought us closer to treating things like colorblindness in humans.