Why Is Blue So Rare In Nature?

Summary

This video script explores why blue is the rarest color in nature, particularly in animals. It delves into how most animals don’t have blue pigments but instead rely on microscopic structures to create the color. Examples like blue butterflies, blue jays, and peacocks use physical structures to manipulate light and produce blue. The script covers the evolutionary and scientific reasons for this phenomenon, discussing how creatures solved a biological problem using physics. It's an engaging blend of evolution, chemistry, and physics, filled with fascinating details about color in the natural world.

Takeaways

• 🦋 Blue is one of the rarest colors in nature, and animals like blue tigers, squirrels, and whales don’t exist.
• 🦋 When we do find blue animals, they often look stunning, as nature goes all out with blue.
• 🦋 Butterflies, especially the Blue Morpho, demonstrate how blue isn't a pigment but is instead caused by the structure of their wings.
• 🦋 The color of a butterfly's wings comes from tiny scales, which reflect light in a specific way to create blue.
• 🦋 Unlike other colors made by pigments, blue in animals comes from microscopic structures that bend light, called structural coloration.
• 🦋 Blue Morpho wings have ridges shaped like Christmas trees that reflect blue light and absorb other colors.
• 🦋 Even birds like blue jays and peacocks get their blue color from feather structures, not pigments.
• 🦋 This phenomenon of structural coloration also explains why some animals, like blue jays and even human blue eyes, appear blue.
• 🦋 Only one known butterfly species, the olivewing, has evolved to create a true blue pigment.
• 🦋 Nature's blue is often the result of evolution using physics and engineering to solve biological problems, creating blue through structures instead of pigments.

Q & A

Why is blue considered a rare color in nature?

Blue is rare in nature because there are almost no animals that produce blue pigments. Instead, blue colors are often created by microscopic structures that manipulate light.

How do butterflies, such as the Blue Morpho, appear blue if they don't have blue pigments?

Blue Morphos and other blue butterflies appear blue due to the microscopic structure of their wing scales, which reflect blue light through a process called structural coloration. The arrangement of ridges on the scales causes light to interfere in a way that only blue light reaches the eye.

What is the difference between pigment-based and structure-based colors?

Pigment-based colors are produced by organic molecules that absorb certain wavelengths of light and reflect others, while structure-based colors are created by microscopic shapes that bend and filter light, reflecting only specific wavelengths like blue.

Why don't blue butterflies lose their color when they get wet in the rainforest?

The wing scales of blue butterflies are naturally water-resistant, allowing them to maintain their color even when wet. The structure of the scales is designed to repel water.

What role does light refraction play in the blue color of animals like butterflies?

Light refraction, the bending of light as it moves from one medium to another, is key to creating structural colors. In blue butterflies, the microscopic structure of the wing scales bends light so that only blue wavelengths are reflected back.

Why do flamingos turn pink, and how is this different from how blue is produced in animals?

Flamingos turn pink due to pigments called carotenoids in the food they eat. This is an example of pigment-based coloration, unlike blue animals, which use structural coloration rather than pigments to appear blue.

How do the feather structures of blue jays differ from those of peacocks in terms of coloration?

Blue jay feathers scatter light through microscopic beads that cancel out all colors except blue. Peacocks also use structural coloration, but their feathers have more ordered, crystal-like structures that reflect light more brightly from certain angles.

Why is there only one known butterfly species with true blue pigment?

True blue pigments are incredibly rare because they require unique chemistry. Only one known butterfly species, the olivewing, has evolved to produce a blue pigment, and the reasons for this are not fully understood.

How do scientists explain the evolution of blue coloration in animals?

Scientists theorize that animals evolved structural coloration to create blue because it was easier for evolution to modify microscopic structures than to invent new pigments. This allowed species like birds and butterflies to develop blue colors for communication and survival.

What historical figures were fascinated by the structural colors of animals, and why?

Robert Hooke and Isaac Newton were both fascinated by the structural colors of animals like peacock feathers. Hooke described them as 'fantastical,' and Newton recognized something unusual about blue light, sparking centuries of scientific curiosity.

Outlines

00:00

🦋 Why Blue is Rare in Nature

The video begins by noting the rarity of blue animals, such as tigers, bats, squirrels, and even blue whales, whose color isn’t as blue as expected. Despite the lack of blue in most species, the blue animals that do exist are often striking. The journey to understand this phenomenon requires delving into evolution, chemistry, and physics. The narrator introduces Bob Robbins, a butterfly expert, to explore how butterflies use colors for communication. Butterfly wings display a variety of colors, most of which are created through pigments derived from their diet, as seen in flamingos turning pink from crustacean pigments. However, blue in butterflies is different, as it isn’t formed by pigments but by the microscopic structure of their wing scales.

05:01

🔬 The Science Behind Blue in Nature

Blue in butterflies, like the Blue Morpho, comes from the microscopic structure of their wings, not pigment. Tiny ridges on their wings act like optical filters, reflecting only blue light and canceling out other colors. The blue appears even more vivid due to an underlying pigment that absorbs stray red and green light. This phenomenon relies on how light waves interact with the structure. When the gaps between these structures are filled with another material, like alcohol, the blue color disappears but returns once the material evaporates. Other blue animals, like blue jays and peacocks, also use structural color instead of pigment. Even human blue eyes are colored this way, making blue pigment in nature exceedingly rare.

Keywords

💡Blue animals

The script emphasizes how blue is an exceptionally rare color in the animal kingdom. Unlike other colors, blue is often not derived from pigments but from structural mechanisms. Blue animals like the Blue Morpho butterfly and blue jays are highlighted as examples of this phenomenon, where their appearance of blue comes from microscopic structures that manipulate light.

💡Pigment

Pigments are molecules that absorb certain wavelengths of light and reflect others, which is how we see color. In most animals, colors like red, yellow, and black are derived from pigments. The video contrasts these colors with blue, explaining that blue is usually not created by pigments but by structural color in nature.

💡Structural color

Structural color refers to the way certain materials are able to reflect and filter light based on their microscopic structures, rather than pigments. The video focuses on this concept to explain how animals like butterflies and blue jays appear blue without having blue pigments. The Blue Morpho butterfly's wing scales are an example of structural color, using tiny ridges that reflect only blue light.

💡Butterflies

Butterflies, specifically the Blue Morpho, are used as a key example to illustrate structural color. The video explains that butterflies evolved to use light for communication, and their bright colors, including blue, help send messages about territory, toxicity, or mating. The butterfly’s wing structure, not pigments, creates its vibrant colors.

💡Iridescence

Iridescence is the phenomenon where colors change depending on the viewing angle, often seen in animals that have structural coloration. The video explains how the Blue Morpho butterfly's wings display iridescent blue due to the arrangement of microscopic ridges that reflect light. This color shift is a hallmark of structural color.

💡Blue Morpho butterfly

The Blue Morpho butterfly is central to the video’s exploration of blue in nature. Its wings reflect a striking blue color not from pigments, but from microscopic structures that filter light. This butterfly serves as the key example of how structural color creates the illusion of blue in animals.

💡Light interference

Light interference is the scientific principle behind structural color. In the video, light waves bounce off different layers of a butterfly's wing, and depending on the wavelength, some light waves cancel out while others reinforce each other. Blue light waves align in a way that they are reflected, while other colors are canceled out.

💡Index of refraction

The index of refraction describes how light bends when it passes from one material to another. In the video, it’s explained how the Blue Morpho butterfly’s structural color disappears when its wings are immersed in alcohol because the refractive properties change. The index of refraction plays a critical role in how light is bent and filtered, which is essential for creating blue coloration.

💡Peacock feathers

Peacock feathers are another example of structural coloration. The video explains that their blue and green colors come not from pigments but from the microstructure of the feathers, which reflect light. The colors are brighter and more vibrant depending on the angle, similar to the Blue Morpho butterfly, but the peacock’s color appears more stable due to the structure's crystal-like organization.

💡Evolution

The video discusses evolution as a driving force behind the development of structural color. It explains that early animals like birds and butterflies evolved to see blue light, but they couldn’t initially produce blue pigments. Instead, evolution favored structural adaptations that manipulated light to create blue coloration, which allowed these animals to use blue in communication and survival.

Highlights

Blue is one of the rarest colors in nature, with very few animals displaying true blue pigmentation.

Butterflies evolved to be active during the day and use their bright colors to communicate messages such as toxicity or territorial claims.

Butterflies like the Blue Morpho don't have blue pigments; their iridescent blue color comes from the microscopic structure of their wing scales.

The blue color in Morpho butterflies is created by the shape of the wing scales, which reflect blue light due to their microscopic structure.

Animals like butterflies and birds don't produce blue pigments from their diets like they do for other colors such as red or yellow.

Blue structures in animals reflect light in ways that create the appearance of blue, rather than containing a blue pigment.

When the gaps in the scales of a Blue Morpho butterfly are filled with alcohol, the blue color disappears, but returns once the alcohol evaporates.

Unlike butterfly wings, blue jays get their color from light-scattering microscopic beads within their feather bristles.

Blue structures in peacock feathers and blue jay feathers work differently, with the peacock's color appearing brighter at certain angles due to more ordered light reflection.

Most blue colors in animals are made from structural changes, not pigments, making blue a very unique color in the animal kingdom.

The only known example of a true blue pigment in butterflies comes from a rare species called the Olivewing.

The rarity of blue in animals is because blue pigments are hard to produce chemically, so evolution solved the problem by using physics and light manipulation.

Scientists theorize that animals evolved to see blue light before they evolved a way to display the color on their bodies.

The study of iridescent blue colors has fascinated scientists since the 1600s, with Robert Hooke and Isaac Newton both noticing unusual qualities in peacock feathers.

Nature’s blue is often created through physical structures that bend and reflect light in specific ways, rather than through chemical pigmentation.

Transcripts

There are no blue tigers.

No blue bats, no blue squirrels, or blue dogs.

Even blue whales aren’t that blue.

Animals come in pretty much every color, but blue seems to be the rarest.

What’s cool, though, is when we do find a blue animal, they’re awesome looking.

Nature doesn’t do halfway with blue.

To understand why this is, we’re gonna journey through evolution, chemistry, and some very

cool physics.

But, first we’re gonna need to understand why animals are any color at all, and to do

that, we need to go look at some butterflies… because butterflies are awesome… and if

you don’t think so, you’re wrong

This is Bob Robbins.

He’s curator of Lepidoptera at the National Museum of Natural History in Washington D.C.

Butterflies ARE awesome.

Make no mistake about it.

They’re a group of moths that evolved to be active during the day, and if you’re

active during the day, you have an advantage: You can use light to communicate.

You probably realize this,

but out of all insects, butterflies display the brightest and most detailed patterns.

And there’s a good reason for that:

The colors in butterfly wings deliver messages, like “I’m toxic”, or “I’m a male

and this is my territory”, but not all butterfly colors are created equal.

If we zoom way in on a butterfly wing, we see the colors come from tiny scales.

It’s actually how moths and butterflies get their scientific name.

Oranges, reds, yellows browns…those scales all contain pigments, organic molecules that

absorb every color except what we see.

Black scales absorb all colors.

Animals, from butterflies to birds to you and me, don’t make these pigments from scratch,

they’re made from ingredients in our diet.

You might know this thanks to flamingos: They’re born gray, but turn pink thanks to pigments

called carotenoids in crustaceans they eat.

So when it comes to these colors: You are what you eat.

But not so for blue.

Blue is *different*

If you move the camera, you can see that the color changes as you move the camera.

It does.

It’s like a hologram thing.

This is because there’s no blue pigment in these butterflies

Wait… so they’re blue, but they’re not really blue?

That’s correct!

Yes.

You’re lying to me butterflies!

These are Blue Morpho butterflies, maybe the prettiest butterflies of all.

I mean… they did make it the butterfly emoji.

The blue color isn’t from a pigment.

The blue comes from the shape of the wing scale itself, and when I learned how this

works, it kinda blew my mind.

If we zoom way in on a blue wing scale, we see these little ridges.

If we slice across the scale, and look closer, we see those ridges are shaped like tiny Christmas

trees.

The arrangement of the branches is what gives Morpho wings their blue color.

When light comes in, some bounces off the top surface.

But some light passes into the layer and reflects off the bottom surface.

For most colors of light, waves reflecting from the top and bottom will be out of phase,

they’ll be canceled out, and that light is removed.

But blue light has just the right wavelength: the reflected light waves are in sync, and

that color makes it to our eye.

This hall of mirrors only lets blue light escape.

There’s even a pigment at the base that absorbs stray red and green light to make

the blue even more pure.

That’s how we get this awesome iridescent blue.

The microscopic structure of the wing itself.

All of this happens because of the way light bends when it moves from air into another

material.

So if we fill all those tiny gaps with something other than air, like alcohol, the blue disappears.

Technically, this “changes the index of refraction”, but in plain English that means

blue light is no longer bent the right way.

The microscopic light filter is broken.

Until the alcohol evaporates.

And the color returns.

But these butterflies live in the rainforest.

You think they’d lose their color any time they got wet, right?

Well watch this.

These wing scales are made of a material that’s naturally water-resistant.

What about this blue jay feather?

If we look through it, the color completely disappears.

No blue pigment.

Each feather bristle contains light-scattering microscopic beads, spaced so everything but

blue light is canceled out.

Unlike the highly-ordered structures we find in butterfly wings, these feather structures

are more messy, like a foam, so instead of changing as we move, the color’s more even

from every direction.

Peacock tail feathers?

Again it’s the shape of the feather, not pigment.

But the light reflecting structures here are more ordered, like a crystal, so it’s brighter

from certain angles.

There’s even a monkey–WHOA let’s keep this PG!!–even that color is made by the

adding and subtracting of light waves thanks to structures in the skin… not pigment.

And yes, even your blue eyes, are colored by structures, not pigments.

Outside of the ocean, almost exclusively, the bluest living things make their colors

with microscopic structures, and each one’s a little different.

No vertebrate, not a single bird or mammal or reptile that we know of, makes a blue pigment

on its body.

In fact, there’s only one known butterfly that has cracked the code for making a true

blue pigment.

Blue as a pigment in nature is incredibly rare.

But there’s one exception so far that we know about, and these are over here called

the olivewings.

They have evolved a blue pigment.

They’re not very common and we don’t know much about them, and I don’t know of any

other blue pigment.

That’s a really special butterfly.

Why is almost all of nature’s blue made from structures and not pigments like everything

else?

I’ve asked this question to several scientists that study color, and here’s their best

theory so far: At some point way back in time, birds and butterflies evolved the ability

to see blue light.

But they hadn’t yet evolved a way to paint their bodies that color.

But if they could, it’d be like going from early Beatles to Sgt.

Pepper’s Beatles.

it meant new opportunities for communicating and survival.

Creating some blue pigment–out of the blue–would have required inventing new chemistry, and

there was no way to just add that recipe to their genes.

It was much easier for evolution to change the shape of their bodies, ever so slightly,

at the most microscopic level, and create blue using physics instead.

They solved a biology problem with engineering.

What I love about this is these colors have fascinated curious people for hundreds of

years.

After looking at peacock feathers through one of the first microscopes back in the 1600’s

Robert Hooke wrote: “these colours are onely fantastical ones”

Even Isaac Newton noticed there was something unusual about these blues, and scientists

have been studying it ever since.

Not only because the science is interesting, but because it’s beautiful.

Thanks for watching, and stay curious.