As the leaves change to glorious gold and copper hues in autumn, it’s a visual feast for human eyes. But what do our pets see?
Posted: 04 September 2019
What would it be like to see the world through our pets’ eyes? Do they see the colours in a similar way to how we do? Would we understand them better if we could see what they see?
In fact, different animals see different kinds of hues – some see very little colour, while some, such as bees and butterflies, see more than we can. This makes perfect sense as these little creatures spend their time flitting from flower to flower, using their super-colour sense to seek out the best nectar and pollen.
When it comes to understanding what colours our pets can see and how the world looks through their eyes, things get rather complicated. This is because colour doesn’t actually exist. When light hits our eyes, special photoreceptor cells turn it into nerve impulses, which are passed to the brain and processed into ‘colours’.
The process works like this: When light hits an object, such as an orange, the object absorbs some of that light and reflects the rest of it. That reflected light enters the human eye through the cornea, which bends light towards the pupil. This controls the amount of light that hits the lens. The lens then focuses the light on the retina – the layer of nerve cells in the back of the eye. The retina has two different types of cells that detect and respond to light – rods and cones. Rods are activated in low light, whereas cones, which provide the eye’s colour sensitivity, are stimulated in brighter environments. Humans have about 6 million cones, and 110 million rods. This arrangement means that while we can see lots of colours in daylight, at night, we just see shades of grey.
Although the popular belief that dogs can only see in black and white is not true, canines do have fewer photoreceptor cells in their eyes than humans, so the colour range they see is more like that of a human who has red-green colour blindness. Rather than the full colour spectrum, canines see in various shades of blue, yellow and green. They also can’t determine how bright a colour is as well as humans. This means, in bright light, the world may seem a bit on the blurry side to them.
DID YOU KNOW?
It’s in low light that a dog’s vision comes into its own. Dogs have more rods that activate in dim light in their eyes than humans. This gives them sharper vision in very low light – such as at dawn and dusk – which is ideal for hunting and likely harks back to their ancient wolf ancestry.
When it comes to movement, dogs also have the edge, as they’re able to spot fast-moving objects – or prey – easier than we can. Also, with the position of their eyes, dogs have a wider field of view.
Canines also have an additional after-dark secret weapon – a reflective mechanism called the tapetum lucidum. This means that they can reflect the light that goes into their eyes back out, allowing a much more detailed view of the world in darkness. Wouldn’t it be amazing to see what our pet dogs see when the sun goes down?
Cats also have a high concentration of rod receptors and a low concentration of cone receptors, so they can’t see colours so distinctly, but they can see well in low light. They also possess the tapetum lucidum, which enhances their excellent night vision – a basic requirement for stealthy after-dark hunters. This is also what gives felines that spooky eye glow in the dark. Cats are not well equipped to see objects at long distance, which makes perfect sense as felines are stalk and pounce hunters who are hardwired to laser-focus on nearby prey.
Unsurprisingly, eyes have developed in different species to do a specific job. With rabbits, their vision is primarily required for quickly and effectively detecting approaching predators from almost any direction. Their eyes – set high and to the side of their head – allow them to see nearly 360 degrees. Research suggests that rabbits do have a limited ability to discriminate between some wavelengths of light, particularly what we see as ‘green’ and blue’. And, as the rabbit retina has a much higher ratio of rods to cones than the human retina, bunnies can see better than us in low light.
Scientific research suggests that guinea pigs – along with horses and sheep – have better colour vision than cats, dogs and most other animals. It makes sense for them to be able to distinguish colours as this might be an effective way of seeing movement around them. And, while they have a poor perception of depth, guineas can see 33 images per second, whereas humans see only 22. This means they see dynamic motion more accurately than we do – which is really important when you’re a small prey animal. What’s more, their range of vision is about 340 degrees, while humans only have a range of 180 to 200 degrees. This allows them to see their surroundings without moving – which is another clever adaptation. Prey animals often play dead when they sense danger so it’s very important for guinea pigs to be able to spot a predator approaching without moving an inch.
Ferrets have ‘binocular’ or ‘stereoscopic’ vision, meaning that their eyes are placed more to the sides of their heads than human eyes are. This gives them much better peripheral vision than us. Ferrets don't see much detail beyond a few feet, although at close range – say one or two ferret lengths – they actually see better detail than humans and cats. Ferrets have a blind spot right in front of their nose, which is why they sniff when looking at something close-up.Ferret eyes also have a tapetum lucidum and work best at twilight, an ability that was probably inherited from wild polecat cousins who hunted at dusk and dawn.
Rats, who are naturally nocturnal creatures, have poor eyesight and can see only hints of ultraviolet, blues and greens and blurry edges. They use their other senses to navigate the environment, find food and recognise one another in the dark. They probably see with some clarity only up to a few feet away – beyond that, they are only able to make out large shapes and movement. Their eyes, however, have a really useful adaptation – they can see in two directions at once. This means that while one eye scans the environment at ground level, the other can be fixated upward, helping the rat avoid predators – such as hawks and owls – from above.
Wild hamsters live mostly underground, only venturing out at night, so they don’t need great eyesight. Instead, hamsters interpret the world through sounds, scents and touch. At birth, hamsters are completely blind and in adulthood can only see a few inches past their nose. These little creatures do have a large number of rod cells in their retinas, which are important for vision in low lighting. This is why they are more active at night when they can make the most of their low-light vision to search for food. Although traditionally thought to be colour blind, studies are now indicating that some hamsters may be able to faintly see blue and green lights.
According to research published in the US National Library of Medicine, as nocturnal creatures with poor eyesight, mice cannot see very well in the light or the dark. When scurrying about, mice tend to run along the sides of walls and other objects and use their whiskers (vibrissae) for guidance. However, as their eyes conveniently jut out prominently from their heads, mice are able to pick up on motion from all different sides and as far away as 45 feet – an ability that helps to keep them out of danger.
Nocturnal, nap-loving chinchillas also have very poor eyesightand tend to rely on their whiskers in order to ‘see’ or sense their surroundings and navigate the world around them. That’s why you should always approach them slowly so they can use their other senses to work out it’s their friendly human, not a predator out to get them!
Degus, unlike many small pets, have very good vision – which is reflected in the fact that they are active in the daytime. Their retinas include rod cells and two types of cone cells, corresponding to peak sensitivity in the green and ultraviolet regions of the colour spectrum. Behavioural experiments have shown that degus are able to discriminate ultraviolet light from the wavelengths visible to humans. This ultraviolet sensitivity is likely to be a social function, as both their stomach fur and urine are highly UV reflective. So, like tiny CSI detectives, they can use their ultraviolet vision skills to see who’s been on their patch.
The season of mists and a multitude of dangers...
With piles of falling leaves to dive into and all manner of seasonal smells to investigate, autumn is a sensational scent adventure for outdoor pet explorers – but there are numerous hazards lurking in the misty murk...
Why it’s great to have a pet
They’re our companions, our best friends and they can transform lives.
Messy pets give our health a boost
Don’t get too carried away cleaning as the minuscule microbes that animals bring inside our homes can be good for us.
How to tell if you have a happy pet
Wheek-wheeking, bruxing, dooking, chirping, binkying, popcorning – there are all sorts of ways our pets tell us they’re feeling good, once you know what to look for...
Why pets are so good for our mental wellbeing
The unconditional love and companionships pet animals provide can be a lifeline for people contending with mental health issues...
How to keep your kids interested in their pets
Did your son or daughter beg you for a furry friend, but quickly lost interest? How can you keep them involved?
Sources: bluecross.org.uk, akc.org, aao.org, bio.miami.edu, ncbi.him.nih.gov, animals.mom.me, guineapigtube.com, cypresskeep.com, ratbehavioiur.org, mpg.de, 101hamster.com, blog.vetdepot.com, en.wikipedia.org