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  • For animals out there in the wild, it's all about survival.

  • It's important to find food and not be food.

  • And for a lot of animals, they do this just like you were I would... with their eyes.

  • But not all eyes are the same.

  • Animals evolved at different times in different environments,

  • meaning there are whole lot of different eyes out there working in different ways

  • all in the name of survival.

  • As a veterinarian who has traveled the world working with different animals in different

  • places, I've seen this firsthand and it never ceases to amaze me.

  • One of my favorite eyes are goat eyes, which have these horizontal rectangular pupils,

  • great for seeing wider ranges helping to locate predators, when they're grazing.

  • Colossal squid have the biggest eyes in the world,

  • some think the biggest ever, they've evolved to see large

  • objects far away, perfect for spotting sperm whales looking for lunch.

  • But today we're going to be talking about owl eyes.

  • Now there are a lot of things that make owls fascinating animals and fierce hunters;

  • powerful beaks and talons, feathers that actually help them reduce noise as they flap, and some species

  • actually have asymmetrical ears.

  • One is higher than the other.

  • And that helps them locate prey better in the dark.

  • But today I really want to talk about their eyes, and not just because I have this skull,

  • but it helps.

  • This is my great horned owl skull, and it's one of my favorites because I mean if you

  • look at his eyeballs.

  • And you think about the mass, the actual volume that is occupied by eyeballs, it's maybe as

  • much or more than the brain or the rest of the skull, and they're big for a reason.

  • The bigger the eyes, the more the pupils can expand to let in light, which helps them

  • see in the dark.

  • That's why you see a lot of nocturnal animals with those big eyes like the tarsier.

  • We're not really going to get into the details of the tarsier but come on, we needed to

  • show you what they look like.

  • Bigger eyes also means more space between the lens,

  • the front of the eye, and the retina at the back of the eye.

  • This distance helps the owl's eyes focus on a bigger and more sharp image on their retina,

  • resulting in their impressive vision.

  • For example, the tawny owl can see about two or three times better than us humans, but

  • of course vision varies from owl to owl.

  • The other amazing thing about owl eyes is their shape.

  • Usually when referencing eyes we talked about eyeballs.

  • But in this case, owls have eye tubes.

  • Scientists believe that as birds evolved, their center of gravity moved to the center

  • of their body to help with the balance of flying.

  • So their heads had to become lighter.

  • This is the reason owls have tubular eyes, a tubular eye takes up less space than a round

  • or globular eye, and in turn weighs less, but it doesn't lose that distance between the

  • lens and the retina.

  • So the owl can have a lighter eye, and still maintain their amazing vision, but this tubular

  • shape also meant they lost some of their peripheral vision.

  • The opposite of those goat eyes I love so much.

  • Owl eyes are also fixed socket eyes, held in

  • place by a bone called the sclerotic ring. This along with their limited peripheral vision

  • means that if an owl wants to see left, right, up or down,

  • they have to physically move their head.

  • Luckily, they've evolved in a way to help them do that.

  • Now you may have heard the fact that owls can turn their heads 270 degrees, which might

  • be true, but this fun fact might be a little deceptive.

  • First off, if I told you I could rotate my head 180 degrees, would you believe me.

  • Well, let me show you.

  • See, this 270 degree fact isn't telling you the starting point, which makes it a little

  • misleading.

  • Now what owls can definitely do is see behind them, and even further if

  • they need and turn completely upside down.

  • This is all due to a few things.

  • First, most owls have 14 neck vertebrae.

  • Humans have just seven.

  • This gives them that amazing flexibility, but their flexibility is also thanks to the

  • joint between their neck and their head called the atlanto-occipital articulation joint.

  • Now as humans have two of these joints that are connected to our skull, giving us limited

  • range, but owls only have one, giving them the ability to pivot around, kind of like

  • a robot.

  • These two adaptations help make up for the fact that they can't move their eyes.

  • So taking in all this information about their eyes, their skulls, their necks, not to mention

  • the things we didn't get into like their ears, feathers, beaks, wings, talons, you can start

  • to get a picture of why these birds are such elite hunters, but that doesn't mean they're

  • immune to the troubles affecting so many animals out there.

  • Look at my little patient today.

  • This is a screech owl.

  • Pretty cool, huh?

  • From a conservation standpoint my experience when working with owls has mostly been with

  • wildlife rescues, and these are animals that were maybe orphaned or they were injured.

  • And so they need some medical help to potentially and hopefully get them back into the wild.

  • Luckily, around the world are amazing organizations studying owls rescuing owls and helping preserve

  • not only new generations, but the environments where they live.

  • Because look owls not only have an important place in the ecosystem.

  • They can also greatly benefit us.

  • Farmers harness the power of owls' amazing eyes to help naturally

  • control rodent populations that could harm crops.

  • And on top of all that, they're amazing to see in the wild.

  • So let's all work together to make sure they're here for a long time.

  • Thank you so much for watching our new Seeker series Tusks to Tails.

  • I'm Dr. Evan Antin and and if there's an animal you'd like us to feature, leave it in the

  • comments.

  • We'll see you next time.

For animals out there in the wild, it's all about survival.

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B2 eye skull vision tubular retina evolved

Owl Eyes Are Shaped Like Tubes, Here's Why

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    Summer posted on 2021/02/02
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