The mantis shrimp is a true heavy-hitter.

Take this one.

She's about to devour this snail.

But she's gotta crack it open first.

So, she carefully positions it... Then -- BAM!

-- she punches it with the speed of a .22 caliber bullet.

It's the fastest attack in the animal kingdom.

That's one kind of mantis shrimp, known as a smasher.

Here's the other.

This one's called a spearer.

Buried up to his eyeballs, he watches and waits.

Then springs into action, impaling his prey on serrated blade with blinding speed, and dragging it beneath the sand.

What makes these two so amazing isn't just their speed.

It's their eyes.

See those black spots?

They're like our pupils, where the light enters the eye.

We humans have one in each eye.

Each sends an image to the brain... and voila... depth perception.

The mantis shrimp has six of them.

Our vision: binocular.

His vision: hex-nocular.

For when accuracy counts.

As for color?

We've got 3 receptors, red, green, and blue.

The shrimp has 12.

Another world record.

But there's even more to this incredible eye.

And it has to do with something called polarized light.

Sunlight is messy.

It's a jumble of wavelengths, moving in all directions at once.

But some surfaces -- say the scale of a fish, or a pair of polarized sunglasses -- have a way of changing the light, organizing it, so it moves in a single plane.

We humans can't really tell this is happening.

But the mantis shrimp can make out where in the ocean light is being polarized and where it isn't.

Some mantis shrimp take this one step further, and produce their own special kind polarization.

And they use it as a kind of secret code.

See, mantis shrimp are incredibly territorial.

They will defend a burrow to the death.

But some, like our smasher, have a way of avoiding the fight.

When he looks into a burrow, he can tell that another mantis shrimp has already claimed it, by the way light is hitting its body.

That's the secret code.

Here's how it works.

Remember when I said that polarized surfaces organize light into a plane?

Well these surfaces on the mantis shrimp make the beams of light circular, spinning through space like a helix.

And as far as we know, only other mantis shrimp can can detect this with their eyes.

You can see it here because we put a polarizer on the camera.

So, these shrimp have taught us a thing or two.

By reverse engineering the mantis shrimp's eye into a camera, a group of scientists have begun to use polarized light to diagnose injuries and disease.

This scanner measures polarization in red.

See how this mouse tissue goes red when it stretches?

Well, injuries to our tendons do the same under the scanner.

So do some cancers.

This endoscopy footage reveals cancerous cells hiding in plain sight by the way they react to polarized light.

It just goes to show how we see the world differently when we look at it through another set of eyes.