by chelsea schuyler
Last blog I teased you for the second time by denying you rainbow animals so you could appreciate the amazitude of structural coloration. Enough of my nonprofit independent yet corporate-esque false advertising. Taste the rainbow!
Birds have rainbow down pat. Interestingly, though we always think of male birds evolving more and more unique and beautiful colors to attract females, studies are showing that actually both sexes started flashy, and females evolved into duller colors because they don’t need to be flashy. Males, according to the Smithsonian “continued to be dandies to ensure the longevity of their lines.” The next evolutionary question is why the word “dandies” was lost to the common lexicon, despite it clearly being the best most adorable word ever.
Rainbow Gum Tree – Birds sure, but trees? Witness the Rainbow Eucalyptus of Indonesia and the Philippines. Okay, this isn’t technically a rainbow animal, but are we gonna get all semantics on a friggin’ rainbow tree?
With the potential of a 6 foot diameter, this tree doubles its size every year until topping out at 250 feet. Unless you decide to grow it yourself for the low low price of 70$, as it barely reaches 100 ft away from its natural home. Can’t keep Great Whites in a cage without death, can’t grow rainbows away from home without shrinkage.
The rainbow parrotfish – Most commonly photographed by amateur waterproof camera owners, these fish display a myriad of color. However, it’s difficult to appreciate because of their unsettlingly human-like teeth. Those are full on straight, flat, white teeth over there. This is where dentures go when they die. But if you can get over that, grab your snorkel and go for an underwater rainbow.
Also, witness the amazing mandarinfish. After all that talk about how vertebrates can’t make blue, this little fish may be one of two species (the other one is also a mandarinfish) that can make its own blue pigment. The chemicals are listed as ‘unknown chemical composition’. WTF?
These fish are named after the apparently showy robes of imperial Chinese officers (called ‘mandarins’). Besides color, the most bizarre feature is that they have no scales. They are instead covered in a slimy, smelly (worse than regular fish smell?) mucous that I guess does wonders for keeping away parasites and being distasteful to predators. Down, supplement industry!
The Rainbow Leaf Beetle – In unicorn world this is what happens to animals in an oil spill. Yay! These beauty beetles live in Britain on “plants growing in crevices, and beneath stones.” So, on Britain then. It eats wild thyme, which is just so Masterpiece Theater right now. “Oh, yes, well you know, as a British bug I only dine on the finest spices. Not like those filthy dung beetles in less civilized lands…”
Butterflies – Here I’m afraid I can’t help you. In trying to find out if there are any rainbow butterflies, I discovered that Wow are butterflies, as a trend, not dead. Researching ‘butterfly’ is bad enough, but ‘rainbow butterfly’ is just asking for it. I might as well look up ‘adorable glitter kittens’ and expect science.
So, I’m sorry, but I couldn’t get through all the cutesy, tattooy, clip arty, butcheries of biology to find out if there is, in fact, a rainbow butterfly. I wouldn’t be surprised if there was though, because butterflies are show offs.
Some lizards love to dazzle us with color. Others are brown as the desert is hot. My personal first rainbow lizard was the Kenyan Rock Agama, bobbing their heads furiously on the -wait for it – rocks of Kenya. Twist ending!
Chameleons take the cake by being able to change color, but it’s not quiet as controlled as you might think. Now, an octopus has total command of their outside ensemble. Cephalopods such as the octopus can stretch out certain cells that contain pigment. For example, if they have three cells, one red, one white, and one green, they can stretch out green and shrinkify the others, making the whole section look green.
The Cephs use complex organs controlled by muscles to do this, whereas chameleons can do the stretchy thing, but they can’t control it at will. They can only do it when they get certain signals from hormones or neurotransmitters that get uppity from changes in mood, temperature, stress, or visible changes in the surrounding environment.
Octopus color change = cunning display of strategic ingenuity and experience;
Chameleon color change = PMS
The incredible Acanthastrea coral. Remember, coral is an animal. Supposedly. I can never remember why but Sir David Attenborough said so on Blue Planet and the Sir shall not be challenged.
Did you know you can ‘breed’ coral by taking off a hunk, and rubber banding your new fragment (or ‘frag’ as it’s known in the elitist saltwater community) to a rock where it will eventually become permanently attached? Science!
You don’t know. They are birds’ ancestors after all. And actually, to make all our childhood fantasies come true, they are starting to figure out what colors dinosaurs exhibited. Now that we know some dinosaurs had feathers, we can look at the structure of the feathers and identify melanosomes – little organelles that had different shapes depending on which pigment it made. Staying tuned on that one.
Birds, trees, insects, reptiles, coral, dinosaurs. Not seeing a lotta mammal in that list. What’s the deal? Well evolutionary tricks aren’t available to everyone. Structure is complicated, blue just wasn’t in the cards for us, and therefore, neither was rainbow.
We’ve sort of been able to manage blue in the testicles of vervet monkeys and the butts of the baboon-like mandrills. If Nature is at all metaphorical, she might just be allowing the mammals a Blue-Can-Shove-Its-You-Know-What You-Know-Where display.
Otherwise, we just stretch the truth in fits of denial (Blue whale = gray, Russian blue cat = gray)
Side Rant on Blue Eyes
Ooo, except human eyes. Some of us fancy favored types (no author bias here) have blue eyes. In actuality, all humans have blue eyes, in that they all have the structure on the iris (named after Iris, goddess of nature and therefore the rainbow – just sayin) for blue.
However, if you get certain genes that demand brown or green pigment, they will overshadow that blueness. 6,000 – 10,000 thousand years ago (good times), one person in the human race got a mutation to their melanin gene. It didn’t turn off melanin completely (albinism), but merely made it so there was less brown pigment in the eyes, making the blue visible to the naked eye (see what I did there?).
Photos are public domain except:
kingfisher: photo by pkhum CC BY-SA 3.0
gouldian: photo by martin pot CC BY-SA 3.0
large tree: photo by chad podoski CC NC-ND-2.0
small tree: photo by amaderson2 CC BY 2.0
parrot fish: photo by Vincent Chen CC BY-SA 3.0
beetle: no source given, thenakedscientists.com
agama: photo by D. Gordon E. Robertson CC BY-SA 3.0
mandarinfish: photo by I, Luc Viatour CC BY-SA 3.0
vervet: photo by Yoky CC BY-SA 3.0
baboon: photo by Robert Young CC BY 2.0
human eye: photo by Michael Phillips CC BY 2.0