Structural color: why you can't make blue powder from a morpho butterfly

November 13, 2014 9:37 AM

What do a dead blue snake that was green when it lived, a modified, hardened beetle forewing that is still vibrant after 50 million years (PDF), the shiny blue Pollia condensata berries (previously), and a wide variety of blue-colored birds have in common? Structural coloration, specifically the structural designs of a variety of reflective prism structures that overcome the natural difficulty to create blue (and green) colors.
posted by filthy light thief (27 comments total)

Fun fact, the MetaFilter's blue background is not actually blue. It is made up of reflective chitinous scales.
posted by prize bull octorok at 10:02 AM on November 13, 2014 [18 favorites]

Overharvesting of Basiliscus beanplatus,¹ the lizard that supplies these scales, has become a serious problem. Some populations face total collapse. That's why they've switched new users to a professional — and sustainable! — white background.

1: For unclear reasons, Basiliscus beanplatus is commonly known as the "hardcore tater lizard."
posted by You Can't Tip a Buick at 10:09 AM on November 13, 2014 [4 favorites]

1: For unclear reasons, Basiliscus beanplatus is commonly known as the "hardcore tater lizard."

That's what happens when you translate from Latin to English via Greek and French.

Love the tags: "He was a rough, green snake, probably the hardest snake in the jungle..."
posted by marienbad at 10:28 AM on November 13, 2014

I wonder if this is related somehow?
posted by valkane at 10:36 AM on November 13, 2014

So, Filthy, this means you can't steal that blue?
posted by Oyéah at 10:38 AM on November 13, 2014

Not to re-rail, but I've been photographing blue morpho and several different butterflies and moths in the last month or so and have definitely noticed this. Under a good macro lens it's really fascinating. Thanks for posting this.
posted by nevercalm at 10:41 AM on November 13, 2014 [2 favorites]

There were some blues I just couldn't get out of my old digital camera, and even less with a printing process. I am all better now, I do it with oil paint.
posted by Oyéah at 10:46 AM on November 13, 2014

Obscure-but-totally-true-and-not-a-paid-shill: Basilicus beanplatus gets that color from a steady diet of Pepsi Blue.
posted by briank at 10:46 AM on November 13, 2014 [2 favorites]

That's what happens when you translate from Latin to English via Greek and French.

I just input "hardcore tater lizard" into the Bad Translator.
43 translations later: "This color"!
posted by Kabanos at 10:48 AM on November 13, 2014 [3 favorites]

Oh cool, one of my friends works with the MacLachlan Group at UBC, and one of that groups main research topics is related to this. He brings some samples to talks with him, they look really cool.
posted by Canageek at 10:50 AM on November 13, 2014 [2 favorites]

The blue I couldn't get was the surface of Campanula Bells they have a that chalky, multifaceted, sort of surface. It makes me think these color technologies have a camoflage function. Maybe though, those types of surfaces serve an insulation function too. So techie, gotta be defense.
posted by Oyéah at 10:55 AM on November 13, 2014

I'm was just googling around some more about animals and their colors, and discovered that Polar bears have black skin and their hair is largely transparent. Mind blown.
posted by Kabanos at 11:02 AM on November 13, 2014 [2 favorites]

Kabanos, you might enjoy the other stories in NPR's Color Decoded: Stories That Span The Spectrum, which is a pretty broad collection of interesting stories, from the history of red in textiles to how an accidental primer color became the look of the iconic Golden Gate Bridge, to optical tricks and the use colors as descriptors for a variety of things.
posted by filthy light thief at 11:12 AM on November 13, 2014 [5 favorites]

From my experience, it's always lighting. Sometimes it takes me 20 or 30 minutes to find the right angle, but I've never had trouble reproducing the right color. It's much harder to get the color I want over the entire field, often the slightest change of viewing angle causes the color to drop off or disappear.
posted by nevercalm at 11:21 AM on November 13, 2014

Kabanos, that claims that polar bears' skin fluoresces under UV light, which seemed crazy enough to me that I tried to find more about this. Instead I found this. Their hair is basically translucent, but diffuses the light that hits it. I think that's basically the same deal as most other white haired animals.
posted by aubilenon at 11:21 AM on November 13, 2014

That translucent hair probably has an absorption function, having to do with vitamin D and survival in low intensity light.they need the insulation, but the black skin would be super absorbent of spectra and energy
posted by Oyéah at 11:32 AM on November 13, 2014

Oh cool, one of my friends works with the MacLachlan Group at UBC, and one of that groups main research topics is related to this. He brings some samples to talks with him, they look really cool.


Small world! I was in the MacLachlan group until recently, working on a structural color project. Structural color is the best you guys.
posted by beepbeepboopboop at 12:18 PM on November 13, 2014 [1 favorite]

Structural color is super neat. In a previous life I was part of a research group that worked in the not-unrelated field of photonics. It wasn't my area, but I got to attend some really fascinating presentations on it. I was just describing the effect to my girlfriend the other day when we saw a bunch of butterflies! Though butterfly lover that she is, she did not appreciate my observation that because of how they work, their wings change color when you dip them in acetone.

Related and also very neat: certain beetles' shells reflect circularly polarized light, which they may use to signal each other in a way that almost no other creature on earth can detect.
posted by solotoro at 12:49 PM on November 13, 2014 [4 favorites]

As an optical engineer, this hits on my favorite optical fact: peacock feathers are brown. Banded in varying hues of brown, but simply brown. Hold one in front of a light (which overwhelms the reflections off the Newton's-Rings-like structures with true absorption color). It's brown.
posted by IAmBroom at 1:30 PM on November 13, 2014

Can I put on my bragging hat for a moment? I am going to put on my bragging hat for a moment. Thanks to this wonderful light-bending phenomenon, I believe I've bred the first blue seahorses in existence. By accident. (It's not as impressive as it sounds unless you're a fish geek and/or love science-y bits.) Seahorses can change to a multitude of colors thanks to chromatophores (color changing cells, like the ones cephalopods have, but not quite as fast). The one color they're not able to do is blue. In fact, their color changing abilities are what have stymied seahorse breeders who want to produce the most vibrant, therefore desirable, colors. So when I decided to attempt to breed for color, I decided to target the white coloration that often overlays other colors, assuming they were iridophores, and try to increase it, in hopes it wouldn't be so changeable.

Low and behold, one day, I looked among the I was raising young and found a blue seahorse. Of course I had to grab my husband and confirm I hadn't been stricken by some rare form of late-onset color blindness. But blue she was.

I had a suspicion of what happened, but it wasn't until a small aquarium event a few months later where marine breeders and researchers mingled that I got to speak to someone to confirm and clarify what had happened - one of the researchers there was studying chromatophores, had published a couple papers on the subject knew exactly what happened. Sure enough, I was targeting iridophores with my breeding efforts, and something caused them to change shape just enough to reflect blue instead of white.

Since I noticed it, I've noticed a few of her kin also have blue patches, just not to that extent. Unfortunately, I have no offspring from her or her siblings, but I'm hoping. I just sent off a couple siblings to a fellow breeder in hopes that even if mine doesn't produce any soon, they're are more chances for this trait to survive.
posted by [insert clever name here] at 1:48 PM on November 13, 2014 [18 favorites]

I frickin' love MeFites. I'd love to hear more from people who have studied structural color (and about seahorse breeding and studying).
posted by filthy light thief at 5:58 PM on November 13, 2014 [2 favorites]

One of my friends from grad school is really into structural colour (Hill lab, now his own) especially the nanostructure. The coolest thing is that colour is fossilizable which is how you can tell what colour dinosaurs were (brown - I really wanted crazy peacock dinosaurs but apparently they are shades of brown).
posted by hydrobatidae at 8:18 PM on November 13, 2014 [1 favorite]

"Before the eye evolved, you just wouldn't have seen what was there"

Bravo, bravo.
posted by turnips at 8:56 PM on November 13, 2014

I love these posts about color and color vision!

Structural color is crazy. My small parrot is a vibrant, day-glo green color; when her feathers are wet she becomes drab greys and browns.

Years ago I encountered something described as "powdered pearls" in a shop; the product was a dull white shade with no sheen. The salesperson explained tht a pearl's beauty comes from the structure of the pearl itself, and that somehing that would in fact appear pearly would have to contain mica or something similar. Blew my mind at the time.

I would really really like to see those Pollia berries in person.
posted by kinnakeet at 1:10 AM on November 14, 2014 [1 favorite]

> "... the natural difficulty to create blue (and green) colors."

Some years ago, I was watching a cooking show (probably Top Chef?), and the contestants had been challenged to create meals based on various colors. One of the hosts went up to the "blue" group as they were working, and mentioned that they had a real challenge, because there are no naturally blue foods. The contestants looked at each other, and one asked, "... what about blueberries?" The host got very angry, and started shouting "BLUEBERRIES ARE NOT BLUE THEY ARE PURPLE!"

(Incidentally, I have Bizarre Mutant Colorblindness, so for all I knew this was true. So I called to my gf in the next room: "Hey, are blueberries blue?" "Uh ... yes?" "They're not purple?" "No. No, they are not.")

Anyway, my point is, I have no idea what that was all about.
posted by kyrademon at 4:51 AM on November 14, 2014

kyrademon: "BLUEBERRIES ARE NOT BLUE THEY ARE PURPLE!"

Here's the problem:

Whole blueberries are (generally) blue. (Some variants have other hues, obv.)
Blended, mashed, or cooked blueberries are purple.

So, they're both.

See also: blending red strawberries makes a pink pulp, and grinding black peppercorns make a gray powder.
posted by IAmBroom at 12:15 PM on November 14, 2014

Blueberries have anthocyanin pigments which run anywhere from blue to red in color depending on pH. When you crush 'em up, the acidic innards turn the skin redder (i.e. purple)

Blue cheese, on the other hand ...
posted by Kabanos at 9:30 AM on November 17, 2014 [2 favorites]