Deep Look

If you close your eyes and try think about how an insect sees you might picture something like this.

Hollywood has used it as a shorthand for "bug vision" for but it's an idea that goes back centuries.

On a spring day in 1694, Antonie van Leeuwenhoek - the microbiology - used a magnifying a candle through the dissected But instead of seeing 1 candle saw hundreds of tiny flames, But spoiler alert - this is not how insects see.

Hi, I'm Niba, and today we're how insects really see the camera to demonstrate how our out what's going on inside the and try to understand how insects detect motion and Welcome to Big Ideas, a new show behind Deep Look.

While Deep small animal, Big Ideas zooms the big questions about how Okay, let's get up close and with the compound eye.

All adult with vision have them.

And since insects make up oh, somewhere 75 to 80 percent of all known animal species on Earth, the the distinction of being the type of eye in the entire animal But it's not just insects.

Other species have compound eyes, too.

like the mantis shrimp, have do some segmented worms, like that have their compound eyes on a pair of specialized Tentacles that can see.

Now take an even closer look at the insect compound eye.

There's hundreds - sometimes thousands - eye units.

One unit is called an which means "tiny eye" in Greek.

are ommatidia.

And each one has This is different from our eyes.

camera eyes, and each eye has Let's break this down even focused through this lens onto eye - the retina - where a bunch of cells called photoreceptors turn it into an electrical to our brain to build a picture We can see how this works with# an old-fashioned device called a camera obscura.

Early models - an actual room or a tent.

Light comes in through a tiny then projects an upside-down world onto the wall.

It was kind of like having a photograph Over time, more portable models were invented.

We've made our own portable obscura, but DIY-style, using and a glass lens.

You can home.

The lens here is like the focusing the light onto tracing back - just like how light hits And when I look into it - oh wow - it kind of looks like eight- push the lens closer or farther until I get the focus just What's projected here is an But when light hits our retina, send that visual info to our then interprets the image Now it's tempting to think that in our camera eye might be in a compound eye.

Take the each ommatidium creates, stack top to bottom, and you might what old van Leeuwenhoek saw So why then does a fly, with like 6,000 ommatidia, not see Because each ommatidium is only receiving light from a tiny segment of the picture - but not the entire Check out this diagram of a cross-section of an ommatidium.

See this long column deep and narrow, so only a of light - containing the visual from a really small section of image - can pass through the top and make its way down to the What that means is that each only send a tiny piece of visual the insect's brain, where together to create a full and So an insect with hundreds of ommatidia might be seeing Scientists like to think of it pixels on a TV screen, where ommatidium is a single pixel a small portion of the overall Add more pixels and you can get wider field of view.

Like the example.

With around 9,000 globular eyes, it has extreme You can also add more pixels, but make them smaller, which you better resolution - a This is basically what the It has around 30,000 ommatidia close as possible.

It's a big has some of the sharpest vision And it's no accident that can pack together so tightly.

in their shape - they're meaning they have six sides.

the most efficient shape to a surface and not waste space.

But there's a wrinkle to all of this.

Cause despite thousands of the dragonfly's compound eye ends up producing a low-quality From our perspective, it would look kind of pixelated.

Turns out that even one of the# best compound eyes on the planet can't compete with our camera when it comes to creating That's because we have more room on our retina to densely pack meaning that we're sending much more visual information to our The human eye has millions of photoreceptors.

A single but really they function together like one photoreceptor So even the mighty dragonfly - with 30,000 ommatidia - really 30,000 bits of visual its brain, compared to millions But hold on a sec.

If insect vision is so low-quality, then clock a predator sneaking up to them their next meal?

How do identify prey so they don't advantage does the compound eye Basically, insects' eyes are# really good at detecting motion.

A lot of them see faster than us, so their eyes and brains visual information much quicker What that means is that for the world is moving in slow motion compared to how we So if we're looking at a the second hand move like this.

it would look something like hand is moving almost four times means they have almost four much process time to detect and movement, and their brain is together almost four times This is why it's so hard to get fly with a fly swatter.

Try as quickly as you can, and you - because to them, you're Seeing in slow motion doesn't insects avoid being prey.

It them fantastic predators.

It's a reason why the dragonfly is to be the most efficient in the entire animal kingdom.

It can calculate exactly where its will be to land the perfect And it's not just motion that compound eye does differently.

which adds a whole new layer to how a species can avoid find food, and make a real go of it in this crazy world of But first, let's understand how we see colors.

The photoreceptors in our# camera eyes are trichromatic, so we can see the three colors green, and blue.

We combine different ways to see the full of colors that we call visible Quick science-class moment here: light is electromagnetic composed of different We can't see a lot of these what we can see falls in this the shortest wavelength at nanometers, all the way up to the longest wavelength at around 700 nanometers.

Other light that are shorter or longer don't get picked up by our eyes.

But many insects can detect shorter wavelengths, which include light that we can't see - like ultraviolet Many flowers have UV reflective are invisible to our human eye attract bees.

For these aerial these patterns are like airport with little landing zones that the parts of the plant with The dragonfly takes color up to eleven - literally.

One showed that dragonflies can or maybe even more, different This brings us to the# biggest question of them all.

Can we ever truly know what the experience of seeing is like for We can't even be certain of what people see.

Color, for example, brain.

It's a perception created brain's interpretation of light objects - meaning color itself the object, but rather a So maybe - just maybe - the blue see might not look exactly like And so the same reasoning might how an insect's brain is rule things out.

We can make educated guesses.

But we can't Want to see animals using their amazing eyesight to survive?

episode about mantis shrimp - of light that are invisible to peregrine falcons keep track of as they fly towards it at high See you there.