xanthophores

th3mstrmind-deactivated20170607  asked:

Hey there. I was at the pet store today and saw a beautifully colored albino cornsnake; fall colors of reds+orange and a little yellow, with some white. It made me wonder, why are they called albino's if they come in such vibrant colors?

GOOD QUESTION! So basically, albinism is a condition that knocks out a pigment called melanin. This is the primary pigment in many animals, including mammals and birds. It colors skin, hair, scales, feathers, and eyes. There’s different types of melanin that produce colors on a spectrum ranging from deep black to sandy blonde. But while melanin is the primary pigment in mammals, it’s not the only pigment in reptiles! Reptiles actually have two types of pigment-producing cells. The first, melanocytes, produce melanin. In an albino animal, those are basically turned off and the skin is white or pinkish from the blood circulating beneath it. But reptiles also have what’s called chromatophores. Chromatophores produce many other pigments. Two of these are xanthophores (yellow) and erythrophores (a range of red to purplish, depending on the species). Some reptiles have iridiophores (which produce iridescent colors) and there’s two other common pigments known as guanophores and leucophores (two different versions of white). Each of these pigments is affected by different mutations! So for example, my Kenyan sand boa is anerythristic, which means that the genes that control red pigment (the erythrophores) have been turned off- giving me a black and white snake instead of a black and orange snake like a normal KSB. My ball pythons are both axanthic, which means that the genes that control yellow pigment (xanthophores) have been turned off. These snakes don’t produce these pigments, and so that changes their color!

So that snake you saw was an albino in that they don’t produce melanin! But their other pigments are unaffected by the mutation, so they can still exhibit gorgeous shades of red, yellow, and orange! 

pomrania  asked:

Please talk more about comparative space-anatomy and biology! I am honestly interested in this stuff; and as someone who has exams soon, I know the feel. Any way you can make twi'lek stuff relevant to what you have to study?

YES oooooooo I have a whole entire deal with them, and it is color based. We see a WIDE range of Twi’lek Colors, I will focus now on White, Flesh Tones (we only see a pale “white” tone but the whole range of human pigments could be possible), Red, Orange Yellow, Green, Blue, and Purple. 

Now, these colors are not all present in mammals, so I’m going to have to talk about bird/reptile systems, but we can extrapolate.

Color is formed by two methods- pigment and structural color. Within the dermis, there are several types of pigment cells. There are melanophores, responsible for black, brown, and even a ruddy red color like you might find naturally in human hair. There are also xanthophores, which produce yellow-orange colors, and erythrophores, which produce red colors.

Now for the color blue, you need something special- it isn’t a color the body can just produce through pigment. In the case of feathers, the actual physical structure of the plumes is altered to make a special reflective structure. In skin and scales, it requires iridophores or cyanophores, which are actually filled with compounds that physically alter the way light is reflected. Now in both cases, for the blue to show, a layer of black pigment (melanin) MUST be present underneath. Without the layer of melanin (or other pigment), the feathers/scales/etc will simply appear to be whatever the base color is, white or yellow or red or whatever.

So, using combinations of pigments and structural colors, we can create break down the colors of Twi’leks.

White- No melanin or other pigments present. Structural color may or may not be present, but will not show without melanin.

Flesh Tones- Varying degrees of melanin. No other pigments or structural color.

Red- Erythrophores present. No structural color.

Orange- Erythrophores and Xanthophores present. No structural color.

Yellow- Xanthophores present. No structural color.

Green- Xanthophores and structural color. 

Blue- Melanin and structural color. 

Purple- Erythrophores and structural color present. 

Thus, it would be possible to predict the color of the children of Twi’leks based on the homo/heterozygosity of the parents for different pigment types and the presence/absence of structural color. But that is a whoooooole other talk in itself!

*Note, this also does not include rare pigment types select to a few taxa. For example, Turacos actually do have green pigment instead of yellow pigments + structural color, but this pigment (turacoverdin) has not been found in any other taxonomic group.

anonymous asked:

What's the difference between an animal being leucistic and albino? What causes it, I mean. I know leucistic animals can have eyes that aren't pink but I'm not sure why. Also isn't there a type of albinism that doesn't affect the eyes? If so, how can you tell that apart from a leucistic animal?

there are a bunch of differences!

One is that albinism leaves you with a body that has melanocytes but doesn’t produce any melanin. The bits are there, but nothing is working.

In leucism there are not melanocytes to be found. Which also relates us to the next difference: complete leucism doesn’t have any sort of pigment in the affected body parts. It’s snow white. Albinos don’t do that. See, in albinos, only the melanin isn’t happening. If you’re looking at any animal species that has something else, say xanthophores (they contain a yellow pigment) you don’t get snowwhite, you get a yellow. You know those yellow ball pythons? Those are genuine albinos, they  don’t have any melanin in them. But since they have other pigments, they’re not white. 

Now onto the eye difference, that one’s actually funky to explain because fetal development is weird my dude.

Ok, so the vast majority of your melanin producing cells stem from your neural crest. The neural crest is a cell grouping that you get during fetal development. Over times, the cells of the neural crest specify into all sorts of things: melanocytes (eyyyy), cranial cartilage/bone, peripheral nerves + glia and a bunch of other stuff. The melanocytes in the eyes however come from the neural tube. That’s a different bit of fetus that later turns into the central nervous system, and importantly here, your retina. So if the cells that come from the neural tube have melanocytes you get eye colors.

Whereas in albinism it doesn’t matter if there are melanocytes present anywhere because they don’t do their job of producing any melanin. 

Since the melanocytes in skin and eye have different origins, there is a chance that the eyes ones manage to dodge out of the mutations that cause leucism. another result of that is piebald patterning. In piebald patterning you have some cells that have melanocytes and working melanin and some that don’t so you get bigger or smaller patches of normally colored animal and then some bits that are just white. 

2

Chameleons! (Family Chamaeleonidae)

The chameleon family is a fairly large family of lizards, and has approximately 180 members. Most of the larger species have prehensile tails, many have elaborate head crests, and all of them have long, rapidly extruding tongues.

They all also change color! Despite popular perception, chameleons don’t change color based on their surroundings. Though most of them are very well-adapted to blend into their environments while relaxed, their chromatophores (sub-dermal expandable pigment cells) will adjust based upon mood (including threat level), and in some species, temperature.

There are four sets of chromatophores. In the top layer (just under the epidermis), are erythrophores and xanthophores, which display a red or yellow color, respectively. Below that are iridophores and guanophores (interesting fact: “guanophore” isn’t proper Latin/Greek terminology - it comes from the Spanish/Quecha Guano/Huanu, meaning “bird dung”), which can give the chameleon blue/indigo or white pigment. Below the rest are the melanophores, which impart a black pigment.

Tigurini Historiae Animalium lib. I. Conrad Gesner, 1551.

Also I got bored at work and made some chameleons. Happy Valentine’s day?

Got a closeup of some Doryteuthis pealeii hatchlings!  Chromatophores are the cells responsible for the color changing camouflage in cephalopods. You can see that one of the hatchlings has the chromatophores on its head activated, showing yellow (xanthophores) and maroon pigment (erythrophores), while the other squid has inactive chromatophores (dark dots).

For more information on chromatophores, you can watch my former mentor Roger Hanlon go into much more detail on youtube here!