How the Morpho Butterfly Can Be Blue But Also Not Really Blue

[Announcer] This is the most striking blue

in the animal kingdom.

Oh, also, the morpho butterfly doesn't have a speck

of blue pigment at all.

It makes sense, trust me here.

You'll find the morpho butterfly

in the forests of South and Central America.

You'd think that the wonderful blue

would make the butterfly more conspicuous to predators

and you'd be right.

But it also needs to spot other butterflies.

This is especially true of males

who are highly territorial.

Plus, when the morpho closes it's wings,

it flashes a more subdued pattern that helps it blend in.

So blue is for signaling and brown is for camouflage.

And if it needs to startle an approaching predator

hopefully these eye spots will do.

But back to the blue.

It isn't actually a pigment.

Instead, this is known as structural coloration

and it's all about tricks of light.

The blue side of the wing is covered in special scales.

When light hits these,

the scales absorb all the component colors of that light

save for blue, which they reflect back at your eyeball.

That's why the wings seem to change color

depending on the angle.

It has nothing to do with pigment,

but a shift in how the blue light is reflected.

And that my friends, is how to look blue

without actually being blue.