Category Archives: Color Theory

The Glass Menagerie

“Is there such a thing as an invisible animal? In the sea, yes. Thousands! millions! All the larvae, all the little nauplii and tornarias, all the microscopic things, the jelly-fish. In the sea there are more things invisible than visible! I never thought of that before. And in the ponds too! All those little pond-life things—specks of colourless translucent jelly! But in air? No!… If a man was made of glass he would still be visible.”
–H.G. Wells, “The Invisible Man”.

I have written about invisible animals before, and all the ways in which one can become invisible, of which transparency is only one. I’ve spent some time thinking about transparent animals, from the Glass Frog of Central America:

to the Glass Squid of the deep oceans:

The transparency of the frog is obvious as a means of camouflage, but it is less certain in the case of the squid. Does its transparency serve to make it invisible? Or is there simply so little available light that producing pigments of any sort is wasteful? A great number of deep-ocean animals are transparent, including the Phronima, a type of amphipod with a glass-like exoskeleton, and the sea cucumbers which make up 90% of the complex animals on the abyssal plain. But the depths are not the only dark places on Earth; in the subterranean grottoes live the “troglobites,” animals adapted to the life in the sub-basement of the world:

The Alabama Cave Shrimp:

The Transparent Cave Crayfish:

And the Glass Goby:

Where these animals live, there is not even a stray photon bouncing off the stalactites, and so even the term “invisible” is inherently useless. There’s no such thing as “visible” there. To make an admittedly silly pop culture reference, I’m reminded of the character Invisible Boy from the 1999 film Mystery Men. On a team of quirky superheroes with dubious “powers,” Invisible Boy’s abilities are the most useless: He can only turn invisible when no one’s looking. The majority of “invisible” animals have the same superpower: their transparency is just a by-product of another adaptation, because where they live, nobody could see them even if they were day-glo orange.

“Visibility depends on the action of the visible bodies on light. Either a body absorbs light, or it reflects or refracts it, or does all these things. If it neither reflects nor refracts nor absorbs light, it cannot of itself be visible. You see an opaque red box, for instance, because the colour absorbs some of the light and reflects the rest, all the red part of the light, to you. If it did not absorb any particular part of the light, but reflected it all, then it would be a shining white box… A glass box would not be so brilliant, not so clearly visible, as a diamond box, because there would be less refraction and reflection. See that? From certain points of view you would see quite clearly through it… And if you put a sheet of common white glass in water… it would vanish almost altogether, because light passing from water to glass is only slightly refracted or reflected or indeed affected in any way.”

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The Rainbow Boxer

For a guy who goes by the handle “The Quantum Biologist,” I sure don’t talk much about physics. So as an example of physics in biology, I present one of the most fantastic creatures in natural history, the Mantis Shrimp. I would say it’s almost too awesome for this world, except that I think the world is so awesome. The world is awesome, and the Mantis Shrimp is irrefutable proof.

The Mantis Shrimp is not a shrimp, and he will beat you senseless if you call him one. He’s a stomatopod, an order of crustaceans who resemble an unholy hybrid of space aliens and Chinese dragons. (Or maybe dragon rolls?) Generally solitary, often monogamous, and always spoiling for a fight, the mantis shrimp lives in burrows it excavates beneath corals, where it lurks in wait for some snot-nosed crab to walk by. Mantis shrimp have a few claims to fame in the animal kingdom, and the first one is this: they have the fastest punch in the world. How fast, exactly? When asking about any animal’s fighting prowess, I find it helpful to ask the question, “Were it of proportionate size, would it win in a fight against Bruce Lee?” Well, Bruce Lee’s punches were so fast that the film had to be slowed down just so they were visible. The mantis shrimp’s punches are literally as fast as a .22 caliber bullet, and, like the pistol shrimp’s claw, creates a cavitation bubble that flashes white light as it collapses into a blisteringly hot shock wave. It carries 10,000 g’s of force. It completes the entire punch in under three thousandths of a second. And it does it in water.

Bruce Lee:

Mantis Shrimp:

Mama said knock you out

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I recently had a conversation with a crazy red-headed friend of mine about his crazy red-headed ex-wife and why their crazy red-headed daughter is so crazy. You know the stereotype: redheads are supposed to be sharp-tongued, hot-headed, sex-crazed nutjobs. This led me to wonder: Are redheads actually nutjobs, and if so, why would that be true?

My first instinct is to say that the stereotype is bunk. It fits a pattern of maligning every genetic phenotype for the purpose of convenient pigeonholing, and holds no more water than saying that all blondes are dumb, or that big-handed men are well-endowed. The world population of redheads, currently estimated at 1%, would seem to have no more nutjobs in it than any other hair color, and there are plenty of level-headed gingers in the world. The recessive gene that gave us Caligula was the same that gave us Queen Elizabeth I.

Though as far as “sex-crazed,” we can only fantasize.

(In the interest of full disclosure: While not a redhead per se — my hair color was once described by a hairdresser friend as “medium maize” — I come from a redheaded family and even express the gene in the form of a perfectly ginger beard when I go too long between shaves. So as a below-the-ears redhead, I’m not exactly neutral. However, I can say objectively that my immediate family is composed of sharp-tongued hot-heads of which I am one. As for the sexual proclivities of redheads, I’ll decline to comment because, hey, that’s my sister.)

Cultural stereotypes aside, I’m intrigued by the fact that a gene for coloration could carry with it a gene for some other effect. For example, the efficiency of some birds’ immune systems are linked to plumage color. And as Darwin noticed, albino animals are more prone to deafness. So is it possible for the redhead gene to carry with it another gene which might influence behavior? Actually, yes.

First: A Natural History of Redheads. Red hair is caused by the pigment phaeomelanin, which is in turn caused by a mutation in the melanocortin 1 receptor (MC1R) protein which is controls what type of melanin our cells produce. So, essentially, redheads are mutants. But the reason for the evolution of this mutation is unclear. It is found in people worldwide, even in Africans, Aborigines and Persians, but of course it’s most prevalent in Western and Northern Europeans, where it is expressed by 2-6% of the population. One theory posits that the defective MC1R receptor was successful in Europe for the same reason white skin was: pale people absorb more heat and more ultraviolet radiation, which can make all the difference in sun-forsaken countries prone to Vitamin D deficiencies. Essentially, the MC1R mutation served to make your whites whiter. (The Neanderthals possessed the ginger gene, too. Somewhere in prehistoric Europe was a club-wielding caveman Ron Howard.) The only problem with this theory is that there’s no evidence for positive selection in this environment; blondes get sunburns just like redheads, so the recessive gene shouldn’t have given any advantage to our freckly forefathers and should thus have been squelched.

Also, it can’t explain why Carrot Top’s ancestors weren’t violently erased from the genetic line.

A second proposal is that red hair was promoted not by competitive selection, but by sexual selection. (Somewhere in prehistoric Europe was a berry-picking, wolfskin-clad Christina Hendricks.) As a fan of redheaded girls as much as the next guy with a pulse, I’m more inclined to trust this hypothesis. After all, phaenomelanin is also the pigment responsible for the red coloration of the lips, the nipples, the head of the penis, and the vagina. The secret to your good looks, my redheaded readers, is your vagina-colored hair.

Sexual selection for the mutated MC1R receptor among early hominids.

But what the mutant MC1R receptor also carries is a different relationship to pain. The same MC1R receptor that receives the melanocyte-stimulating hormone which colors your hair also receives another, more popular hormone: endorphins. (The two hormones are structurally similar.) A 2005 study concluded that redheads are more sensitive to thermal pain, while another found that redheads feel more pain at the dentist and needed 20% more anesthesia than blondes or brunettes. However, another study was said to prove that redheaded women have a higher pain threshold than blondes and brunettes, at least when the pain was noxious (such as electric shocks) and not thermal (such as a curling iron). So, which is it? Are redheads pansies or bad-asses? Are they both? Are they neither? And if red hair really does effect pain thresholds, would that say anything about a common behavior?

As if this article couldn’t get ridiculous enough, let’s make an awkward segue into the “zoological mystery” segment of our program: What if the answer to redheaded temperament and licentiousness could be found in those ultimate redheads, the orangutans?

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You take everything — the laurel and the rose, too! Go on, take them! But, in spite of you, one thing goes with me now and tonight, when I, at last, God behold… and that’s my panache. -The dying words of Cyrano de Bergerac.

Evolution only requires two thing from us: 1) Reproduction, and 2) Survival, which really only matters if you reproduce. So really, one requirement. It doesn’t matter how long you live; it only matters how many offspring you have, and how fit they are. Of course, if you live longer, you improve your chances of having more offspring. But you’ll really improve your chances of having more offspring if you dress so beautifully, so outrageously that you are constantly flirting with death. In other words, if you have panache.

Panache, that quality so highly prized by Cyrano de Bergerac and swashbucklers everywhere, means “flamboyant confidence of style or manner.” But literally, a panache is the long feather in the cap of a young braggodocio — think of the ostrich plume in the hat of a Musketeer or the pheasant tailfeather in Robin Hood’s archer cap. And when it comes to panache, in every sense of the word, no animal does it better than the King of Saxony Bird of Paradise, one of Papua New Guinea’s many splendid fops.

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Yesterday I said there are no venomous birds. I didn’t say there were no poisonous birds.

Meet the pitohui, the world’s only known poisonous bird. The pitohui, found only in New Guinea, exudes a neurotoxic alkaloid through its skin and feathers, the same toxin found in the poison dart frogs of Central and South America. The poison, which affects both the nerves and the heart, is about ten times more potent than the one found in the fugu blowfish and fifteen times more powerful than curare. But neither the bird nor the frog produce the toxin themselves; they absorb it from the toxic beetles that they eat. And so poison is spread up the food chain: manufactured by a plant for its defense, a beetle gains a tolerance for it and uses the poison for its own defense. Then a bird develops an antidote, and gains the gift. And with this poison, which is in essence a life-preserving agent, comes the gift of color.

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After yesterday’s post about indigo animals, I thought I’d write about my favorite violet one.

Meet Janthina, the violet sea snail. It lives at the surface of the ocean, where it preys on jellyfish and hydrozoans, particularly Velella, the By-The-Wind Sailor. Unlike Velella, which rides the surface of the waves from above, Janthina rides the surface from below, on a raft of bubbles encased in tough chitin, like Huckleberry Finn through the looking-glass.

For the violet sea snail, up is down. The sky is its floor. Its prey lives underground, in the air. Floating along at the mercy of the current and the storms, it has no concept of terra firma, yet is rooted to a surface in all weather. That surface is the same we row our boats in, yet opposite. When you need some perspective – emotional or scientific – think of the violet sea snail, and you’ll remember that every “in” is an “out” door, every window looks both ways, every floor is a ceiling. And every floor is also your shadow’s floor, and that life walks with you in mirror-image, upside-down in your footsteps.

The Biology of Indigo

This post isn’t so much about an animal as about its color: indigo. You see, the other day, a little rainbow came through a prism at my window and landed on my hand. I studied the little rainbow, and it reminded me of a fact of nature that I had forgotten: that indigo is its own color.

To be crudely scientific, indigo is any color on the electromagnetic spectrum between 420-450 nanometers in wavelength. It was first designated a spectral color by Sir Isaac Newton, but it has clearly been there between “blue” and “violet” in a rainbow ever since light first diffracted in water. However, we do not discern it as being different from blue. Physics does. But we do not. We lump it in with the nearly endless variations of blue that we have categorized on our paint wheels: phthalo, cerulean, baby, robin’s-egg, midnight, navy, cyan. It turns out that the human eye is relatively insensitive to changes in hue between blue and violet, which is why we may not be able to “see” indigo, even when we’re looking straight at it. Which makes me wonder: If physics calls indigo its own color, does biology? How do other animals perceive it?

There were two species that came immediately to mind. One is the Indigo Snake, the longest snake in the United States, at over 9 feet. It lives in the Deep South, where it preys on anything large enough to swallow, including rattlesnakes, to whose venom it is immune. Its color is iridescent, turning red-purple in bright light.

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