(soft music) - [Narrator] Have you ever wondered what the world would look like
with a different set of eyes? And I don't mean from another
person's point of view, but from a whole other
creature's perspective. It turns out members of the animal kingdom see the world in vastly
different ways to how we do. From having a set of glowing
eyes that can see in the dark tO superpowered vision that sees colors we
literally can't even imagine, let's take a look at how
different animals see the world. (siren wailing)
(upbeat music) (animation exhales)
(chimes tinkling) Eyes For Bones. Dogs love a game of fetch, but have you ever noticed that sometimes when you throw something for a dog, they can seem to find it? It's all too obvious to you
where it's lying in the grass, but for some reason your
furry friend keeps missing it. Your dog might just be
having a labra-dumb moment, but if the toy is red or green, then it may be almost impossible for your dog to spot it. That's because dogs are
red-green colorblind. A bright red toy to them
would appear a drab gray and would easily get lost in
the equally gray-looking grass. That's because color vision is determined by special
cells on the retina at the back of the eye, known as cones. Humans have three types of cone
cells, blue, green, and red, which allow us to see all
the colors in between. But dogs only have two
types of cone cells, which let them see blue and
yellow, not red or green. When yellow light shines
on these cone cells, neurons in the dog's brain get excited while neurons are suppressed when blue light hits the cones. A dog's brain interprets this excitation or suppression of its neurons as the sensation of yellow
or blue colors respectively. Meanwhile, red and green light have no effect on the dog's brain. With no signal to interpret these colors, they instead registered as gray. So dogs literally live in a
world with 50 shades of gray. Oh, no, forget I said that please. Now, I've seen enough tear-jerking
dog and owner reunions on YouTube that I get
targeted ads for tissues. But have you ever noticed that dog never seems to recognize
their owner from far away? It's only when they get closer
that the tail wagging starts. Well, that's because a dog's vision is much blurrier than humans. Perfect human eyesight is 20/20, where you can see objects that are 20 feet away from you clearly. Dogs are estimated to have 20/75 vision, meaning they have to be 20
feet away to discern details that most people can see from 75 feet. Now, you may be wondering if
dogs have such blurry vision, then why are they used as
guides for blind people? Surely that's the blind leading the blind. Well, some dog breeds such as Labradors have vision closer to 20/20 accuracy and are most commonly
used as seeing-eye dogs. Whereas other breeds
such as German Shepherds, Rottweilers, and Miniature Schnauzers are more short-sighted at 20/75. Dogs may not be able to
pass a letter eye test, but they have far better
motion detection than humans. That's because dogs are
descended from wolves and have eyes evolved
for hunting on the move. (upbeat animated music) So for example, if a light bulb was flickering
60 times per second, humans would perceive the
light as shining steadily. However, a dog's eyes could
detect the light blinking. The light bulb would have to be flickering 75 times per second for the dog to perceive it
as a constant light source. And whilst humans may need to turn on the
lights in the evening, dogs can see things just fine. Hounds have far superior vision in low-light condition than humans do as dogs have far more rod cells which determine light from
dark in their eyes than humans. So dogs' eyes aren't
necessarily worse than ours, just adapted to view the
world in a different way. So next time you're playing with your dog, help them out if they're struggling to locate that red ball on the grass. Life's rough when you're colorblind. Now, it may sound like
dogs have superhuman sight, but right now you, yes, you, can join a super human fight, thanks to this video
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(air whooshing) Purr-fect View. Any cat owners will know that most cats will
happily spend their days napping on the bed, sleeping in the sun, or loafing on the couch, but at night they'll spring into action, disrupting your sleep with
their constant shenanigans, whether that's tapping your
face or making a ruckus. (cat yowling) Despite what it feels like, these late hour antics aren't because your cat
wants to lose sleep, but rather cats are more active at night because they can actually
see a whole lot better. This is because of the distribution of cone versus rod
cells than a cat's eyes. Cats have six to eight times
more rod cells than humans do. As we know, more rod cells
mean cats have superior vision in low-light conditions. It also means cats have better
motion detection than humans because rod cells are
fine tuned motion sensors, being far more sensitive to
light input than cone cells. Rod cells are able to respond to individual particles
of light known as photons, granting much better low-light vision. Cats' eyes also have a feature that gives them an extra
advantage in the dark. If you've ever shown a torch at a cat, you've probably noticed the creepy, shiny effect in their eyes. Are all cats possessed? Luckily, no. That freaky mirroring is because cats have a literal mirror at the back of their eyes, known as the tapetum. It's a layer of tissue that reflects light back onto the retina, allowing the eye to capture
more light in dim conditions. So any intruding mice will
have no chance sneaking around without getting caught at night. But despite being
formidable foes at night, cats can't see too clearly during the day. That's because they have a
limited number of cone cells and seeing bright light
is a cone cell function. Humans have 10 times more
cone cells than cats do, and though cat's eyes have
three types of cone cells, scientists are unsure if cats can see the full range
of colors that humans can. It's suspected that their vision is limited to only blues and grays with far less richness and
saturation in the colors. If you put this screen you're
watching this on right now on low saturation mode, it'd be similar to how
your cat sees the world. Cats are also incredibly short-sighted. So while a human with 20/20
vision can see objects clearly at 100 to 200 feet away, cats can only see things
as far as 20 feet away. So if you're stood across the room, your cat might not be ignoring you, but rather it's unable
to see that you're there. Cats may not have the best daytime vision, but they do possess an ability
to maximize their cuteness more than a hundredfold, literally. When their eyes go from devilish slits to the cutest overblown
pupils you've ever seen, aw. While humans can expand
their pupils 15-fold, cats are capable of an
unbelievable 300-fold change. But as cute as it looks,
experienced cat owners know that they only get
these overblown pupils when they're about to poun-gah! A cat's ability to expand their pupil size gives them a competitive
edge as predators, allowing them to better approximate
distance from their prey by honing their depth perception to focus on a target. But big cats, such as tigers
and lions have circular pupils. Scientists theorize this
difference in pupil shape is due to their larger size. Because big cats are
further away from the ground than their domesticated mini versions, Their eyes don't have to perform as many perception enhancing
tricks to focus on a target. So maybe cats' antisocial behavior isn't down to their personalities but because they struggle to see. Sounds like we need to train guide dogs to assist these short-sighted kitties. I can't see how that could go wrong. Well, I'm still more of a
dog person than a cat lover, but what about you? All those on team dog, see if you can hit that like button. But if you're team cat, try aiming for that subscribe button. All done? Great. Now let's take a look at
the side of some animals that are more than your average pet. (air whooshing) So Egg-Sighting. Red, orange, yellow, green,
blue, indigo, and violet. Those are all the colors of the rainbow, at least the colors we can see. Have you ever wondered
what's beyond the rainbow? You won't find a pot of gold, but a whole range of other colors. They're invisible to you and me, but birds have been able
to see them all along. Okay, I am aware of how crazy
that sounds, but stay with me. First, you need to know that light exists along a
spectrum of wavelengths. Humans can see light wavelengths from 400 nanometers to 700 nanometers, covering the spectrum from violet to red, but the light spectrum extends
beyond what we can see, with longer wavelengths
forming infrared light. You may also know this as heat vision because infrared light is
produced by thermal radiation emitted off of heat-producing objects. There are also wavelengths of light on the other end of the scale shorter than even the violet
wavelengths we can see, known as ultraviolet light. Now you've probably heard
about those harmful UV, also known as ultraviolet rays that we all have to wear
sunblock to protect against, but ultraviolet light also produces an array of incredible colors. These colors, again,
are invisible to humans, but to try and describe them, they're purpler than any
purple you can imagine. And birds can see colors all along the ultraviolet light spectrum. While humans' blue cone cells
can perceive some wavelengths of UV light, the lens and corneas of
our eyes filter it out as UV rays hold high energy
radiation that can be harmful. To counteract this, birds have specialized
oil droplets in their eyes that protect their retinas from damage by screening out excess UV light. With this incredible ability to see otherwise invisible ultraviolet light, birds can perceive unique
colors in other birds' feathers, allowing them to communicate
with and attract mates without drawing the
attention of predators. So birds have been secretly hosting their own neon paint
parties in broad daylight this whole time. Now, you may think of
pigeons as stupid birds, which I agree they are. I got pooped on one time
and I've never forgotten. But for, oh, their terrible aim, they actually have some of the best eyes in the animal kingdom. Pigeons have a staggering
340-degree field of vision without even moving their heads. They literally have an
inception-esque view of the city. This comes down to their eye placement on the sides of their heads, meaning they can see both
directly in front of themselves and above themselves, along with behind their
heads and below themselves all at once. The reason for this is because as prey, they need to have an expansive view to be alert to incoming predators. However, this incredible
range comes at a cost. We humans, for example, have
eyes at the front of our heads, giving us a near 180-degree
view of what's before us. As our eyes are lined up,
each eye's image overlaps, and it's this area of
overlap that allows our brain to approximate distances as we have two different
perspectives of the same scene. Want proof? Okay, stick your finger up in front of you and then alternate closing your eyes. Your finger seems to shift even though you're holding it still, but when you focus on it with both eyes, your brain triangulates its location within this space around you, allowing you to approximate how far it is away from your eyes. Neat, right? While pigeons only have
a small amount of overlap at the front of their eyes, and as a result they
can't triangulate well and have extremely poor depth perception. Higher up the food chain, birds of prey have
insanely powerful vision. Top amongst them has to be
America's mascot, the eagle. Eagle eyes are up to eight
times stronger than a human's because eagles can have eyes that have more than 1
million cone and rod cells per square millimeter of their retina, compared to a human's mere
200,000 per square millimeter. These cones are very
small and tightly grouped, allowing the eagle's brain to process way more detail
from extreme distances, meaning they can detect any
movement from their prey from almost two miles away. A solid runner up though is hawks. Red-tailed hawks in particular can see a mouse from
100 feet up in the air, which is equivalent to if
you tried to spot a mouse on the street looking down
from a 10th-storey window. Hawks can also triangulate an object by tilting their head back and forth, giving them precision estimates
of how far away a prey is. Their ultraviolet vision
also comes into play as some rodent sleep trails
of urine with UV reflectance. Hawks are able to follow these UV trails straight back to their praise nest. Though hawks and eagles may
have the keenest eyesight in the daytime, the bird with the best night
vision goggles are owls. Owls have about 30 times more rod and cone cells than humans, giving them phenomenally
precise night vision. In fact, owl eyes are so well developed that they are not eyeballs,
rather elongated tubes. For this reason, owl's eyes
are mounted in a fixed position which cannot roll or move. They make up for this though by being able to turn their heads up to 270 degrees left or right instead. So clearly birds have amazing vision, and in comparison, our human
eyes are totally boring. But rest assured, we can
hold one thing over birds, and that's our ability
to recognize windows. (wings flapping)
- Come on. Good boy. (dog barking)
(bird thuds) Oh, no. (air whooshing) - [Narrator] Fincredible Senses. Swimming in the ocean
is one of the best parts of being on vacation, until something brushes
up against your leg, ugh. You can never be sure what's
lurking in the depths below, and if you lose your goggles, then everything becomes blurry. Now the lens in our eye works because it's curve shape bends and focuses light between
two different mediums, the air and the liquid
in front of your pupil, known as the aqueous humor. When light enters water, it slows down, slightly impacting what's
called the refractive index. Air has a refractive index of one, meaning its path doesn't bend much, but water has a refractive index of 1.333, meaning it bends significantly. However, our fluid-filled eyes have a similar refractive
index to that of water, so the lens hardly bends
the light in water at all, meaning it doesn't focus onto our retina, leaving us with a blurry image. Sharks on the other hand, can see you paddling about
in the water clear as day. While their eyes are
similar to that of a humans, they have a large spherical
lens adapted to water instead of a squished, curved one, meaning they have 10 times
better vision than humans in clear water. And if that wasn't terrifying enough, there's no direction for
you to hide from sharks. With eyes on both sides of their heads, giving them a near
360-degree field of vision. the only blind spot on a shark are right in front of its
nose and behind its head. But if you think it's a good
idea to hide from a shark by swimming in front of its nose, then you're going to earn
yourself a Darwin Award. Sharks may not be able to see you there, but they can smell you. Some shark's noses are so sensitive, they can detect one teaspoon of blood in an average sized swimming pool. So good luck trying to hide
in front of its nose, buddy. Even deep sea scuba divers
swimming in the murky waters aren't safe from sharks. You may not be able to see
them, but they can see you. Water molecules scatter
and absorb sunlight. This means the deeper you go, the dimmer it gets in the ocean. Below 300 feet, There is no
natural color vision at all. Not that this bothers sharks.
They're mostly color blind. Their eyes are instead equipped to handle the low-light waters. Sharks possess a tapetum that reflects light
back onto their retinas. A shark's tapetum is twice as
effective at reflecting light than a cat's. So if you ever shine a light in the ocean and see mirrored eyes staring back at you, that's not a scuba diving cat. (air whooshing) Itentacle Sights. Octopuses, wait, octopi? Hmm. Both are right,
but I prefer octopuses. Anyway, octopuses, unlike me, are considered some of the
smartest creatures on the planet, and they haven't just impressed scientists by opening eight jars at once. Rather, octopuses can perfectly
imitate their environment by changing their color and
even the texture of their skin. But what's most unbelievable is that they perform all
these color changing tricks while being colorblind. Octopuses' eyes only have
one type of light receptor, which means they can only
see in black and white, or at least that's what
scientists thought. It turns out octopuses actually operate on a whole other level to humans. Octopuses and their
tentacled cephalopod cousins, cuttlefish and squid, can all see color. They just see it in a
completely unique way, and this is down to
their crazy pupil shapes. Humans have circular pupils
that can contract or dilate, controlling the amount of light let in. But you may have noticed whenever you've been in a
dimly lit room for a long time, that you start to see colorful
fringes around objects. That's because when your
pupils are fully dilated in low light, this creates an effect known
as chromatic aberration. The lens of your eye acts like a prism and splits white light
into its component colors. The larger the size of your pupil, the more these colors are spread out, creating this colorful fuzz effect. Meanwhile, octopuses
with their bizarre pupils have the ability to amplify
this chromatic aberration. Scientists believe
octopuses determine color by bringing specific wavelengths of light into focus on their retina, adjusting their lenses to bend some wavelengths
of light more than others. So an octopus could figure out
the actual color of an object based on when it blurs. Scientists have built a computer
model for an octopus eye and showed that for an object
at least one body length away, they could determine the object's color by altering their focus. The W-shaped pupils of cuttlefish make this chromatic blurring
effect even more extreme. But cuttlefish in particular
are also sensitive to polarized light, an aspect of light that's
invisible to humans. Most light waves travel in an S shape, whether it's vertical, horizontal,
or anything in between. The waves that make up
sunlight, for example, are evenly distributed across all angles. Polarized light, however, is made up of waves with
vibrations at only one angle. Humans are sensitive to
some polarized light, but colorblind cuttlefish
are super sensitive to almost all polarized light. So while a human might see this, a cuttlefish would process
the same image like this, where the colors represent the different angles of polarization the cuttlefish is detecting. As we can't process light waves the same, we may never be able to truly see what colors the cuttlefish
experience such as scene in. But what we do know is
that shrimp look far cooler to a cuttlefish than they do to us. (air whooshing) Buzz Life. It's annoying when a hair
gets in your eye, isn't it? Well, bees never have that problem because hair literally
grows in their eyes. The superfine hair that
grows in bee's eyes, it's theorized to give them the ability to sense wind direction as they navigate. But bees actually have five eyes. Can you spot the other three? In addition to the two large eyes on either side of its head, a bee has three ocelli eyes
on the top of its head. These primitive eyes
are able to detect light but not distinct shapes, and act as an early
warning system for the bee to avoid being attacked by
a predator flying overhead. With all this, they can detect motion in as little as 1/300 of a second, whereas humans can only detect motion at one 1/50 of a second. A field of flowers may
appear still to humans, but bees are able to
see the micro movements of the flowers shifting in the breeze. And because bees like birds
can see ultraviolet light, from a bee's perspective, a flower meadow is lit
up like a rave party. Flowering plants rely on bees to transmit pollen from
one flower to another, allowing them to be fertilized. As a result, many flowers have developed distinctive
ultraviolet patterns that are invisible to the human eye, but act as landing zones for bees, pointing them towards
the part of the plant containing nectar and pollen. The bees are attracted to these flowers where they can feed on nectar while the flower's pollen
sticks to the bee's legs and then is inadvertently
deposited on the next flower. Bees can only see color
along the light spectrum of 300 to 650 nanometers, so
they can't see the color red. Instead, they see blue and
violet colors more strongly. So if you wanna avoid bees at all costs, then style yourself like Doja Cat here and go all in on the red. (air whooshing) Shutterfly. They may look like
little featureless logs, but caterpillars typically
have 10 to 14 small eyelets arranged in a semicircle
around their face. However, these simple eyes
only have the capacity to identify light and dark rather than precise images or color. This means most caterpillars
are practically blind, using other senses to find their way around
the world instead. Meanwhile, butterflies have two large eyes on either side of their head and generally have six
classes of photoreceptors, allowing them to also see all colors, including ultraviolet light. Though some species such as
the Australian Swallowtail boast a whopping 15 photoreceptors, they deploy this ultra colorful vision to search for food. For example, the nectar color guide of the horse chestnut tree
will change from yellow to red when nectar is no longer in production. Butterflies will use these color clues to determine which blossoms to feed from, and you may think it's impossible to tell a male and female butterfly apart, but butterflies actually
use ultraviolet markings to advertise themselves to mates. So while there are
already beautiful insects, humans, unable to see ultraviolet light, are blind to how beautiful they truly are. (air whooshing) Eye Spy. People always say they'd
love to be a fly on the wall to spy on situations, but they never stop to consider what that would actually look like. Human eyes have a single lens, which allows us to focus
images onto the retina of the back of our eye to form a single clear image. But flies have compound eyes
consisting of 12,000 lenses. So rather than forming one
image, they produce hundreds. Each individual lens
focuses incoming light onto a cluster of photoreceptors
that detect light. Simply put, each lens
produces an individual pixel of the fly's vision. As a result, the fly's vision
is fairly low resolution, only a couple thousand pixels, whereas perfect 20/20 human vision has a resolution of 576 million pixels. Yeah, so a fly's point of view is like watching those
early YouTube videos that look like they
were filmed on a potato. Even a cat's blurry vision is better than the fuzzy pixelization of a fly's perspective. A human has good eyesight, but if you want a detailed
view of the action, you'd need a hawk's sharp sight. But despite this poor resolution, a fly's protruding eyes have
a full 360 degree perspective and can process motion far
faster than a human's can. Because their eyes are made
up of thousands of lenses, light can enter from multiple angles rather than a single entry point. When an object is moving, this causes individual light receptors behind each lens in the fly's eye to be turned on and off, creating a flicker effect. This flicker effect is
what processes motion and enhances a fly's speedy reaction time. It's also why they're able
to buzz out of the way whenever you try to swat them, even when you've done your
best to sneak up on them. If a light were flickering, a human could only perceive
it at 60 flashes per second, otherwise the light would appear constant. A fly, however, can see as
many as 250 flashes per second. That's around four times
more flashes per second. For more perspective, if you
took a fly to the movies, the film, which typically rolls at a rate of 24 frames per second, would appear to the fly as a slideshow. So being a fly on the
wall is a terrible idea. Everything would be blurry and going in slow motion
to your perspective, and there's a good chance
someone would swat you. (air whooshing) Viperactive Vision. So far we've covered some incredible eyes, but if I could choose to
have any kind of eyes, then it would be ones that
could see in the dark. I could read without a light,
find things in the shadows, and walk around without
crashing into furniture. It'd be super cool, except it's almost
impossible to see in the dark as vision relies on one thing: light. Though it's only visible light
that is absent in darkness, as there's technically
another kind of light that's produced all of the time. Can you guess what it is? It's very close. In fact, so close. You're producing it right now. Heat. Living things emit infrared
radiation as they generate heat, a form of long wavelength light. While human beings are unable to see it, one kind of creature can: snakes. Some snakes such as pit
vipers and rattlesnakes have a pair of small depressions known as the pit organ
near their nostrils. Scientists have discovered
this specialized organ has a thin internal membrane, which acts as an antenna
for infrared radiation. So vipers can thermally image their prey. This heat vision is so sensitive that snakes can detect even the slightest
temperature differences. A rattlesnake in total darkness can discern the presence of an animal around 10 degrees warmer than
the surrounding environment in a rapid 1/2 second from a
distance of 15 inches away. A stunning feat for snakes but bad luck for any mice who think they might be safe in the dark. But they don't just rely on heat vision. Their eyes also have diverse
sets of rods and cones, which as we know, are what allow us to detect
visible light and color. Snakes have two types of cone cells and are able to see two
colors: blue and green. In addition, some crepuscular snakes, meaning they are active at dawn and dusk, are sensitive to UV light, allowing them to see in
low-light conditions. Whereas snakes that are
more active during the day, such as the golden tree
snake or the vine snake have lenses that block UV light. These lenses that filter and
block UV light are yellow, which is why some snakes
have a golden-eye look. But which would you rather be able to see? Infrared radiation or ultraviolet light? Heat vision, or even more colors? Let me know down in the comments. (air whooshing) Krill Bill. Finally, we've arrived at the animal that has
the best vision of all. You may have thought the
night vision of cats or snakes was impressive, but they have nothing
on this sea creature. Meet the mantis shrimp. A small, aggressive marine crustacean known to inhabit coral reefs in the Indian and Pacific Oceans. Now, the mantis shrimp are
notoriously violent crustaceans. They possess two front
appendages known as dactyl clubs, which they use to punch
through the hard shells of the crabs, clams, and snails they hunt. These fists are spring loaded, able to accelerate from their body at over 50 miles per hour, delivering a force of over 1500 Newtons. But these sucker punch shrimp aren't on this list for
their hunting prowess. Rather, their amazing eyesight. Humans can see three channels of color, but mantis shrimp blow us out of the water as they can perceive a
phenomenal 12 channels of color. Yeah, these feisty little fiends can detect ultraviolet
light like birds and bees, as well as polarized light,
like our cuttlefish comrades. While we establish that human eyes aren't sensitive to polarized light, the mantis shrimp can see up
to six types of polarization. And living in the ocean,
they are the only animal who can see circular polarization, where light rays bounce
off water molecules and form a circle. Scientists theorize that mantis shrimp use polarized light as a compass. So for example, a shrimp
venturing out from its burrow could track the distance it has traveled and then turn around until
the light polarization pattern has changed by 180 degrees to find its way back home. The closest thing to compare
mantis shrimp's eyes to is something literally out of this world: satellites. Mantis shrimp have compound
eyes similar to a fly made up of 10,000 small
photoreceptor units. Some of these photoreceptors are lined up in a strip-like arrangement
across their eyes, and the shrimp sees by scanning this strip
across their subject. Satellites also use
multiple spectral channels arranged in a strip to scan across the world as they fly over. So these jacked-up shrimp have the most colorful
vision out of any creature, and the flamboyant shells to match. Best to admire them from afar though, otherwise, you're in for a mean fishhook. (fist thuds)
(soft music) Which of these animals' eyesight would you most like to have? Let me know down in the comments below, and thanks for watching.
(upbeat music)
