Why do cats have vertical pupils? - Emma Bryce

Dive into the incredible diversity of animal pupils, and how the different shapes indicate the animal’s role in an ecosystem.
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Peering into the eyes of different animals, you’ll see some extraordinarily shaped pupils. House cats, for one, are twilight hunters with vertically elongated pupils. Many grazing animals, like goats, have rectangular pupils. Other animals have crescent- or heart-shaped pupils. So, what’s going on? Why are there so many different pupil shapes? Emma Bryce digs into the science of animal vision.
Lesson by Emma Bryce, directed by Bálint Gelley, CUB Animation Ltd.
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Keep Learning
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View full lesson: ed.ted.com/lessons/why-do-cat...
Dig deeper with additional resources: ed.ted.com/lessons/why-do-cat...
Animator's website: cubanimation.com/en/intro-en
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Thank you so much to our patrons for your support! Without you this video would not be possible! Helen Lee, pam morgan, sarim haq, Juan Pablo Rodriguez Morales, ANNE FINE, Gerardo Castro, Siddharth Toshniwal, Michel-Ange Hortegat, Enes Kirimi, Amaury BISIAUX, Aravind C V, ND, Samyogita Hardikar, Vanessa Graulich, Vandana Gunwani, LvL042, Abdulmohsin Almadi, Andrew Brodski, AJ Lyon, Anandha Krishnan, Geoffrey Bultitude, Mi Mi, Thomas Rothert, Christopher McVay, Carlo Solaroli, Javier Aldavaz, Ivan Yeung, Brian Elieson, Grayson Garbarino, Oge O, Weronika Falkowska, Stefano Esposito, Nevin Spoljaric, Yvonne Feijoo, Sid Chanpuriya, Arjay Arcinue Dineros, Anoom Yasmin, Anoop Varghese, David Yastremski, Noah Webb, B, Erica Guerrero, Roberto Chena, Oliver Koo, Luke Pisano, Andrea Gordon, Aleksandar Donev, Nicole Klau Ibarra, Milo Vermeulen and Ryan Weiler.

[@DD-kc6hg]

A very eye-opening video indeed.

[@abdullahak2204]

😂😅✌️

[@gracyzahora2153]

😂😅✌️

[@My-mf9im]

😂😅👌

[@MrSnejinko]

Badum-tss. Well done, dad. 🤣

[@orangetae9412]

😂😅✌️

[@abhinandanprasadbarnwal8375]

I really want a part 2 to know more about the heart shaped pupils.

[@white6505]

same

[@prfm_setya95]

And "W" pupil too

[@rishavdhariwal4782]

Torogao search it

[@aerox5507]

Japanese people know a lot about those heart shaped pupils

[@rishavdhariwal4782]

@@aerox5507man of culture 😏

[@softarmy2182]

She narrated it so beautifully and along with the adorable pictures by the artists. It didn't feel like a lesson, it felt like a therapy.

[@eckoart.erin.jerome]

It's called tonal AI mind control. SMH

[@sayyidulfajri1005]

I'm totally agree with u,although i am training my listening and reading while see the comments my brain is enjoy the whole video 🤣

[@mooneymakes359]

more evolution brainwashing indoctrination turning people away from God. Ultimately for the greedy to treat people like animals instead of God's creation.

[@rishabhadarsh5227]

I am glad u praised the art of the artist We don't want another world war

[@MostafaElSakari]

I didn’t like it, felt like she was talking down to me

[@pragyaraj4206]

I'm surprised NO ONE is talking about the narrator's voice! Her way of speaking it and tone was soo soothing. That's one of the best voices I've heard in a while.

[@lanamello7445]

Definitely! Would love more videos with her voice. It allows you to take all the information in and it's very soothing

[@ashvinvaidyanathan7239]

Ok lady pipe down

[@Gr95dc]

Completely agreed. I enjoyed listening to her voice a lot.

[@nicocee2431]

Actually these are the type of things you know it works exactly because no one mentions it, it means it properly makes the content flow so the viewer can focus 100% on it

[@ansv3340]

It’s BOT speaking

[@WajihRathore]

Its so cool that Ted Ed answers all these questions that randomly pops in our mind in such a unique, well researched and beautiful way.

[@canned_can_chan4590]

Yeah. And i find these videos simple enough to understand easily and quickly. They're also inspiring and i sometimes find ideas for my projects from these

[@Sehaams]

I know right!!! The funny thing is,I had thought about this same thing few days back when I looked into my cat's eye!! Goshhhh what a coincidence!!!!!

[@erayamejoseph7827]

Just what I was thinking...they always answer random questions that pops up in our mind

[@Strongify03017]

I agree

[@trashboat5270]

Why doesn't my nuts hang equally?

[@anaiya8975]

i love that the tittle makes one think it's a lesson only about cat eyes but it's actually all about pupils. they know we're all cat maniacs

[@abdullahak2204]

Yessss meow meow

[@whuspr]

super smart. not making the title sound broad attracted me towards it, and I enjoyed it

[@woodox4735]

meow

[@dustinday4188]

lol "tittle"

[@woodox4735]

@@dustinday4188 I didnt notice that 😆

[@pirobot668beta]

Slit-pupils have another effect: movement across the visual field is 'amplified' whereas movement up and down is 'diminished'. Aside from telling distance, the vertical slit activates more rods and cones when side to side movement is being observed. PIR motion detectors use patterns of lenses and a single sensing element in a similar way.

[@lililililPitdinolilililil]

Any hhdgjkgjjhcffghh on slit uterus varity

[@tejaskundapur2929]

Noice 👌

[@awesomeguy2380]

This is very helpful

[@MrPanujit]

Your input is highly appreciated _/\_

[@stagdragon3978]

This explains why half the time my cat's advanced eyes can't make out the treat I am throwing to em. It's coming from above.

[@TomPauls007]

clear, concise, accurate, and understandable! I could play at 1.5 speed and understand perfectly. Good job.

[@shinyagumon7015]

I love how everything relating to human biology basically comes down to us being the ultimate everyman. Like we aren't the best at everything, but we are the most adaptable.

[@white6505]

we are in the middle of everything, if you think about it

[@lizebrand]

@@white6505 except for intelligence and stamina

[@white6505]

@@lizebrand we are by far the smartest species

[@user-zi4kk9xn5b]

@@white6505 by human standards so that’s not saying much. It’s subjective, how we measure intelligence varies

[@white6505]

@@user-zi4kk9xn5b if you say that is subjective, you cannot measure inteligence at all. how does that make any sense? do you really think humans aren't any better than mosquitoes or any simpler animal? i don't see them building skycrapers or high tech devices like the ones we are using

[@danyramos8139]

Give the animator a raise! It was wonderful to see each animals POV

[@martinc.720]

For doing their job?

[@EvaWhoDraws]

@@martinc.720 animators are rarely paid well enough

[@kimjongunvevo]

@@martinc.720 it’s just another way of saying that they did a good job.

[@zhankazest]

@@martinc.720 For doing their job well

[@CharGC123]

Speaking of POV I always assumed slit pupils were most common in small, grassland predators to maximize seeing vertically through grass, for ex. small cats, as opposed to the round pupiled large cats, or the artic/mountain cats with open terrain. Good to know all the nuances.

[@ron7182]

Such soothing a voice over smooth animation.

[@Roberto-REME]

Outstanding video production: expertly narrated, loaded with facts and entertaining. Really well done!

[@flyinggeovishapthatcanswim2377]

Video length ✔ Visuals ✔ Narration ✔ Topic ✔ Title ✔ Direct-to-the-point ✔ One of the best educational short videos I've watched

[@magtovi]

You forgot: Cat in the video ✔

[@sayyidulfajri1005]

Couldn't agree more with your comment perhaps i am see the comments while listening and see the video it's already made me satisfy 🤣

[@thefunkiestswag]

cat✔️

[@ThZuao]

Better question, why do they look SO CUTE when their pupils dilate?

[@codegenesis80085]

ikr

[@Kurayamiblack]

Yeah, why DO they look so cute about 0.7 seconds before they pounce on me with murderous intent?

[@jeant6502]

In my theory, it might be because we associate them with eyes of babies.

[@mich5869]

probably because that's when they look more baby-like

[@Akibatai00]

It's to lower our defense before they pounce on us.

[@lexi82815]

I love this channel! I always feel so smart after watching the videos but they aren't boring and keep you entertained! They cover about every topic you would want to know about!

[@pandabatsu755]

This video was amazing and answered so many questions I had. The only thing I’d like to point out is while some snakes do have vertical pupils (like snakes from the boa, python and viper families) not all of them do, and the cobra that was depicted in this video would actually have round pupils. But thats a pretty minor detail. Apart from that, this video was amazing!

[@NickvonZ]

It is an ancient Japanese art to tell the time by a cat's pupils. Prior to the days of electric light, mainly.

[@isabelhuang_1]

That’s wild but so creative

[@macmacbrazze3234]

But won't it just change when the cat is indoors? I'm almost imagining cats being kept outside sitting belly up, with their tails swinging back and forth like pendulums on an antique clock.

[@rileschmidt13]

@@macmacbrazze3234 it changes according to the light, so, if the cat is indoors or outdoors, what influences their pupils is the sun. usually cats' pupils are the most dilated between 6-8ish o'clock both am and pm

[@enryuthescarletmessenger5216]

@@macmacbrazze3234 lmaooooo

[@luigidamo8266]

My Filipino grandmother once told me that the cat's eyes can also be an indicator if it is high or low tide, but I've never verified it so idk if it's true

[@lambadajewo.4143]

It's somehow amazing to think that so much knowledge is in all that surrounds us

[@ayszhang]

We only see who we are by having something else to compare ourselves to

[@Adnan_Khan__111]

That's the design of intelligent Allah.

[@Sumirevins]

There's this thing called Evolution and Natural Selection, but I guess those who're blind by their beliefs will never except it, You can believe whatever you want but when that believe deny Scientific facts that's when you should know that you're wrong

[@rottengirl7852]

The music, voice, and animations were hypnotizing

[@chipmunkpark8826]

Please make a part 2! It was very interesting and well explained. I'm more of a social science person, and even I was able to understand everything

[@ukatoahthecathumanhybrid2272]

Thank you, Ted-Ed, for enlightening us about the creatures that share our world. Amazing animation as well. Keep up the great work! :)

[@sus2029]

Now my day is better

[@buzyparticals3753]

@@sus2029 no I have the best day

[@jammingpython8986]

@@buzyparticals3753 Let’s do a competition about whose day is the best.

[@utkarshsaini5650]

@@buzyparticals3753 check your pupil

[@ukatoahthecathumanhybrid2272]

@Clara ???????

[@prakh1250]

The one with geckos was so cool to know about. Different points of focus allow the gecko to calculate distance it needs to capture pray like a mathematical formula.

[@ferguson8143]

Yeah they learn real quick not to chase their food but to rather sit and wait for thwm to come to it and leopard geckos well start to slowly sway their tails back and forth when they have a lock on food and then just before they lung they shake their tails just like a rattle snake does

[@Roberto-REME]

Outstanding video and great narration.

[@twistedsister226]

Amazing video, wonderful voice-over. Thank you TED-Ed!

[@jebadoiah]

My kitty cat's pupils are only used to give me the stink eye when I don't feed him enough lol

[@aveen9397]

Her voice is sooo soothing

[@digitalife8719]

I love this channel. The voice was so clear and easy to understand.

[@zdspider6778]

This was so freaking interesting. I can see why you have almost 20 mil subscribers. Keep up the good work!

[@rmdhn1]

"So what's going on here? Wouldn't we all like to know" SO TELL US PLEASE

[@zawsrdtygbhjimokpl6998]

after watching an Arthur Isaac video of him mentioning that squids becoming sapient and building a civilization isn't something we consider a threat... I think there's more reason for concern now

[@rmdhn1]

@@zawsrdtygbhjimokpl6998 that just means the ability for them to consent if they build a society which isn't a reason for concern

[@WarmBreezeStudios]

0:51 - 0:56 I like this fast animation of how this cat meows, makes a leap and then looks toward us as we're watching.

[@evangelinaparedes6651]

Great video - thank you for all your great videos TED-Ed!

[@HT-xw1fh]

"it may have", "we don't really know", "maybe", etc. highly informative

[@magicalblox]

Don't just end the video tell us more about the cuttlefish pupils

[@lowgpu1687]

I think they have cuttlefish pupils to see whats above or below them, that way they dont have to rotate their whole body to see.

[@lowgpu1687]

The pupils are long too, which could indicate that they have to see what's in front of them in the water.

[@waterdrop154]

Jesus

[@waterdrop154]

Loves you!

[@frankamassop153]

These video's feel like like bedtime stories. I love them.

[@seviregis7441]

Fascinating. Such precision throughout the creation...

[@ji1160]

this is so cool!!! we need a part two on all the other pupils and why they’re like that

[@MrsJudithWright]

Wow, great lesson. So clear and interesting. Great animation.

[@veryberry39]

I'm so glad this wound up going into detail about a couple other pupil types, after mentioning them at the start. On a lighthearted note, those two people at the end were waving silently at each other for a really awkward length of time. XD

[@no1reallycaresabout2]

3:51 Man that bear is adorable

[@huplim]

I love the detail in the animation. Very engaging!

[@hyderaltamash]

You should also explain about eyes of squids (eve's without blind spots)

[@hyderaltamash]

@Weasel thanks bro

[@waleis602]

@Weasel what do you mean??I'm quite lost....if you don't mind of course

[@Eisae]

@@waleis602 The nerve going from our eyes to the brain blocks some of our photoreceptors... Which is a flaw squids don't have

[@waleis602]

@@Eisae oh ...I see thank you

[@imjusthappytobedepressed1123]

Would have loved a mention about the Mantis Shrimp, it has some of the best vision in all of the animal kingdom, curious to know what their pupils are like.

[@Doublejho]

i'm fairly sure they have compound eyes too

[@loki2240]

The pupils of the mantis shrimp study boxing...

[@pushyasaieraag2141]

@@loki2240 Nice one 😂

[@kavitasanodia4384]

@Clara Uhh yeah, you're definitely getting reported.

[@justayoutuber1906]

I think their compound eyes have more rods/cones allowing them to see 12 colors, rather than our 3.

[@Cat-rh3ut]

The animation is amazing. I love this style so much

[@m4heshd]

Oh my god, this voice. So angelic. I want GPT-4o to have her voice. 😭

[@yepitisnathan]

This was fantastic. This was well designed and a joy to watch, great work everyone involved!

[@doctorfuntime1709]

TED-ED can you do a History On Trial of Nero.

[@Fire-Blast]

Yes do it TED-ED

[@Oggre]

Which Nero ?

[@doctorfuntime1709]

Ogre971 Nero The Emperor of The Roman Empire.

[@doctorfuntime1709]

Weasel yep that Nero.

[@JawadSoomro]

Wow! You explained everything so well. Good job!

[@caylee3316]

I usually enjoy TED-Ed videos, but I’d like to submit a correction for this video. At time 1:41 there is a drawing of what appears to be some type of cobra snake. It is a common misconception that all venomous snakes (like cobras) have slit pupils. However, cobras are part of the elapidae family of snakes, and while venomous, this family of snakes has ‘round’ pupils, not ‘slits’ as indicated. The elapidae family is generally considered to be diurnal (hunt during the day). The viperidae family of snakes, on the other hand, are ‘ambush predators’ and do have the characteristic slit pupil as they hunt at night, yet what is pictured is not a viper.

[@Mskalsndhsikabsjss]

Definitely my favourite channel, so informative in just five minutes and always interesting with great animation. Thank you!!

[@rubigarcia2425]

As an interesting fact, I realized that last week when my street cat was sleeping (REM phase if it's called so), I could open her eyes without waking her and I saw her pupils completely shrunk, and when she woke they automatically widened to adapt to the light. That sure was a cool thing to see.

[@d.dmalhotra6425]

Great video as always! The narrator's voice was so soothing and relaxing!

[@ruru2235]

The cuttlefish’s w-shaped pupils are so cute!

[@Saranaprasadam]

Ever since we evolved out of the oceans, our eyes are basically similar to that of fish from the exterior and it still needs seawater to maintain it's health.

[@frostincubus4045]

That'll be the Aqueous humor, the fluid between the cornea and lens, deeper inside the eyes is vitreous humor, a jelly-like substance

[@PaulG.x]

All cells in the body require isotonic fluids with the same concentration of NaCl as seawater otherwise the cells will absorb too much water and burst or lose water and die.

[@suicicada]

woah, I didn't know goats' eyes rotate when they face the ground. Pretty cool!

[@GinniWallin]

Me neither! I never would've guessed that a mammal was capable of doing such thing.

[@SporkleBM]

Well? I _do_ want to know! Hoping for a part two of this video to come out sometime in the future!! Perhaps we can explore more in-depth the eye of the cuttle fish, or the heart-shaped pupil of a frog! :]

[@chartreusemaiden604]

0:01 because they stalk in grass. It helps them focus and target the prey. Horses and goats and sheeps have horizontal pupils and their eyes positioned on the side of their heads so when their head goes down, so they can still keep a look out for predators. If you are wondering if they can't detect predators coming in front, that is why their are the way the are. Surprisingly tigers do not have vertical pupils.

[@ayanpal1]

Extremely well made and so informative! Yet another reason to LOVE TEDEd

[@36gih]

Once again Ted Ed answering questions I never thought I had. Love it

[@someoneok5876]

Thank you Ted-Ed I found this very interesting and intriguingly informative.

[@nupagagyi]

The artworkand animation is absolutely beautiful.

[@ScaredyCatTactical]

As a biologist I really liked your video. Learning new things everyday.

[@giuliamaffia1556]

This is amazing. Both topic and animation.

[@bjedo3]

The illustrations are super adorable

[@M.C.Blackwell]

This is 5 minutes of incredible information!!!!! Fantastic!

[@TeamCat1128]

I’ve always been fascinated by animals’ pupils! Thank you for this!

[@gothboschincarnate3931]

Me too...always was looking for information.....those on the otherside talk with their eyes.

[@ryanharris1052]

I love how I’m educated on things I never knew I was so interested in until hearing about them. I am one interested pupil.

[@coriolis07]

I’ve been having a rough night and this video really helped calm me down somehow. Thank you, TED-Ed :-)

[@mobaumeister2732]

I just love TEDED for answering all those random questions I get from my kids and things I’ve always wondered about but never remembered to look up. But most of all I love it for the quality animations, and illustrations.

[@eine4768]

Amazing sound design Amazing art Amazing animation And the soothing voice This is perfection

[@onepunchman1953]

Awesome video, art and animation!

[@CarthagoMike]

Would love to see a part 2!

[@Budda2020]

Love the style and animation of this one

[@PlainsPup]

Armored suckermouth catfish (loricariids, or "plecos") have an omega iris that can shade the pupil, creating a U-shaped opening to the eye.

[@jejsemin33]

We need a part 2 and 3

[@jayemespanola3831]

Her voice is very relaxing, I just can close my eyes now.

[@rodrigoborges3876]

Ok that goats aligning their pupils with the horizon at all times thing shook me to the core

[@SabribriRei]

Wouldn't vertical pupils also help in focusing on objects while hiding in grass/brush as a lot of those smaller ambush predators would do?

[@wmgthilgen]

Can you or would you do a video on how preditory birds such as an eagle can see a mouse at a mile away, and at at distents so close it would be able to eat it clearly. I can only assume that birds of prey have a sort of binocular vision. Which they can control as we do when view something far away to something farthure away. But are mandated to have to choose the particular lens measure in degree of power such as a 10mm to the use of a 20 mm. Birds of prey seem to have not only binocular visison but the ability to alter the lens.

[@h4id4r4]

Im guessing they can adapt their depth of field by expanding or shrinking their pupils??? I would also like to know more

[@waterdrop154]

@@h4id4r4 Jesus loves you!

[@AmethystSnow]

The art in this is beautiful

[@akmalrafiaa4772]

Is it possible to transfer the gene for heart-shaped pupils to humans? Just curious.

[@priyanshagrl1721]

If We could transfer genetic traits of one species to another, it'll certainly take the evolutionary process to whole another level! Just imagine Mimicing Limb Regenerations from lizards or making an actual Vampire from bats DNA code or even bring back some extinct species!! *But the most Important thing is that Curiosity!* Just don't stop asking such questions and maybe one day you actually make it possible.

[@bamberghh1691]

@Weasel some humans already glow in the dark, you just run them over

[@ashleshamishra7171]

It reminds me of two scientist who write a book on the answers they give to the questions asked by children Ted ed is doing same kind of work by answering our diff curiosities Great work guys😄

[@nicoledobra]

I think i have one of those books you are talking about. Thank you for reminding me about it!

[@indykatley10317]

Great information and beautiful animation.

[@gwot]

not surprised by any of this except for the goat eyes rotating! that's cool

[@bigpapadrew]

my question is, from house cats to tigers and lions, when do the pupils change shape? big cats seem to have circular pupils.. .this has always been of interest to me

[@iamilibitirenbetter3266]

I have learned way more with Ted Ed than I have with school

[@ooraculo223]

Me too

[@stdev.]

Been wondering for some time. This hits the spot!

[@johnstephens1]

Very interesting facts indeed, and very well presented! One thing worth throwing out there, it is mentioned that cat's pupils on the hunt turn to slits for better direct perception, though all cats I've ever known have their pupils turn completely round as soon as they start hunting something, in most cases for me with toys, even in rather bright situations, with it being more notable in some than others. Though most of them were house cats, and in an outside scenario with prey that behaves a lot more complex the slit technique definitely makes sense.

[@lessonsin30s]

CATS EYES ARE BEAUTIFUL!!!!!!!!!! ❤

[@maiktendo6512]

If you Repent for your sins and have faith in Jesus and you shall have eternal life in paradise ❤🎉

[@davewave1982]

The Cuttlefishes W eye is so shaped because even though they are “colour blind” their unique pupil causes chromatic aberration, splitting the incoming light into rainbow bands which the cuttlefishes brain can then interpret as separate colours.

[@arsiveparkour6251]

Damn that's new. Thanks for the info.

[@waterdrop154]

Jesus loves you!

[@victorespinoza6210]

That whole rotating eyeballs in goats is crazy 😮

[@hermeszeusson4621]

I love these drawings and animations. Good job!

[@helga14278]

Советую! Очень полезная информация!

[@stinkyoldmonk8982]

Nature has already seen everything we will ever discover.

[@Patmargolin22]

nature hasn’t seen these

[@JimSandoval]

My dearest. We love you. Your content is really an entertaining window into your soul. That is what makes people fans of you. It's a relationship. Your vulnerability not only makes your comedy hit hard, it makes us feel comfortable and makes you so wonderfully relatable. Stay safe and know that you matter to us as a human being. So, please be safe and take care.

[@alexpereira105]

Ted Ed answers questions I didn't know I had

[@alto7183]

Es increíble como el cerebro tiene software de los tipos de ojos, lo interesante es similitudes de diseño en los ojos, al parecer es mejor los ojos de Tigre y otros felinos grandes por sus tipos de pupilas y nitidez de cazador, creo los biológos saben más, sería interesante ver cuál sería el ojo humano evolucionado a futuro. Los gatos con pupilas redondas adaptados al ser humano y otras características serían cosas de especies domésticas a futuro lejos de lo salvaje, sería cosa de seleccion y evolución por parte del ser humano.

[@vishwamurthysthoughts4683]

Loved this video very nice ♥️

[@RoseDragoness]

I love the artwork and animation of this one

[@wisehumansaid]

Ending the video with a question, so eyeopening Ted

[@shamasadil3514]

Ted ed be like "let's add more knowledge and decrease the watch time"