The external, visible portion of takma skin consists of two layers. Beneath is the relatively soft and vulnerable epidermis, the equivalent of human skin, but over most of the body the epidermis is protected by a layer of keratinous scales. The scales act as a barrier to infection, as armor for the body, and combined with the epidermis play a role in a takma’s coloration.
The color of the epidermis is determined by the concentrations of two pigments: xanthochrome, which provides a yellow color, and erythrochrome, which provides a red color. Each pigment may occur in different concentrations, and the concentration of each is expressed via two genes. Throughout this wiki, the convention will be to represent the xanthochrome genes with A/a and B/b, and the erythrochrome genes with C/c and D/d; an individual takma will have two copies of each, one from each parent. A skin color genotype could therefore expressed as something like: aaBbCCDd (a brilliant shade of orange-red).
The mechanism of inheritance can be approximated with the statement that each dominant copy of a gene (represented by a capital letter) represents one unit of pigment, while each recessive copy (represented by a lower-case letter) represents no pigment. With two copies of each gene and two genes for each pigment, there is a maximum of four units of each pigment, and thus five gradations of each color (0, 1, 2, 3, and 4 units).
Therefore, an individual with a genotype of AABBCCDD would have the maximum amount of both xanthochrome and erythrochrome, and would have skin of an extremely dark reddish-brown color – generally thought of by takmar as black. Likewise, a genotype of aabbccdd would have the minimum amount of both pigments, and very pale skin (a warm gray, so light as to be almost white). AABBccdd would be a dark goldish color, and aabbCCDD a strong scarlet-red. In the middle of the range, a genotype with two units each of color (such as aaBBCcDd) would produce a bright, soft orange color.
The layer overlaying the epidermis consists of very small, granular, non-overlapping scales, barely distinguishable at any distance but giving a takma's outer surface a slightly bumpy appearance. The scales are typically smooth and rounded on their outer surfaces, so that between this and their tiny size, the overall texture is not particularly rough; the tactile effect might be compared to running one's hand over a layer of thousands of tiny ball bearings.
Takmar may have three different scale types, all of an identical material composition, but with differing microscopic structures: spongiform, massive and stratified. Each has different visual and mechanical properties, its own advantages and disadvantages, and its own associated stereotypes in the eyes of those with other scale types.
The structure underlying each scale type is determined by a gene which can be thought of as having three common alleles: S, responsible for spongiform scales; $, responsible for massive scales; and s, responsible for stratified scales. These three alleles form a dominance series, with s as recessive (or least dominant), $ as more dominant than s but less so than S, and S as most dominant.
Therefore, any individual that has inherited one copy of S (SS, S$, Ss) will, regardless of the nature of their other copy, demonstrate primarily spongiform scales. An inheritor of a copy of $ will not have massive scales if paired with S, but will have them otherwise ($$, $s). Two copies of s, and no other combination, are necessary for stratified scales (ss only).
Spongiform, or cyanic scales, are the most frequently encountered scale type. When the scales are formed, they are permeated with randomly oriented nanochannels. The light scattered back toward the eye is a brilliant, but diffuse and non-iridescent blue. In places where they have been subjected to strong blunt impact, takmar with this scale type may exhibit “bruises” in which the blue color has been removed due to the collapsing of the channels within the matrix; only the underlying skin color shows through (although this itself may be discolored due to the effects of the impact on the epidermis).
Spongiform scales have several evolutionary advantages that may have resulted in their appearance and predominance among the takmar. The range of colors they produce, particularly the greens and near-blacks, may be more suited as camouflage in the rainforests that are their preferred habitat. Likewise, the nanochannels make the scales more permeable to water, allowing it to pass to and from the skin more easily, frequently a necessity in humid climes. This scale type is also the most effective at protecting the skin from pressure and blunt force due to its spongy structure; on the other hand, it is also more vulnerable to piercing by sharp objects, particularly punctures perpendicular to the surface.
Spongiform-scaled individuals have a reputation among the other scale types as easygoing, flexible, and easily able to enjoy life; they are also sometimes seen as silly, impractical, and overly confident.
Massive, or simple scales, are the next most frequent type after spongiform scales. Like the former, they form in single layers; however, they lack interior channels, resulting in a denser, harder, and smoother structure. Although sometimes slightly reflective on the outer surface, the scales are straightforwardly translucent and lend relatively little significant change to the underlying color.
Out of the three scale types, massive scales are the most resistant to damage from sharp objects. They are relatively difficult to puncture, scrape, or abrade. On the other hand, they are less protection from blunt force, being more apt than spongiform scales to transfer shock through to the underlying tissue. The scales themselves have a critical failure point, as well; rather than compressing under severe force, they tend to crack instead, which even in the absence of direct injury to the underlying epidermis can be painful.
Massive scales are something of a throwback to the early evolutionary history of the takmar. The common ancestors of the takmar and the xtauh, like the xtauh themselves, were desert dwellers, and their scales are believed to have been primarily of this type. They are relatively impermeable to water, making it easier to retain it but harder to lose it, particularly in the humid conditions of the takma homeland. Although all takmar have other adaptations to aid them in removing excess water from the body, individuals with massive scales may drink slightly less and have a stronger preference for less humid conditions; they are also somewhat more comfortable in arid climates such as those of the brightness.
Individuals with massive scales tend to have a reputation for toughness, ruggedness, and a straightforward and undemonstrative attitude; they may also be seen as crude, primal, and somewhat irritable. Though they bear a stronger resemblance to the xtauh than other types of takmar, the comparison is usually unwelcome.
Stratified, or lustrous scales, are the rarest of the three types, and apparently an evolutionary modification of the massive type. Rather than being formed and shed in one layer at a time, the scales are continuously generated in extremely thin “sheets” of keratin overlaying each other. The visual result, though often described as metallic, is more of a pearly or semimetallic luster added to the underlying skin color, resulting in descriptions such as “gold”, “copper”, “silver”, or “bronze”.
Stratified scales are middling in effectiveness against blunt force and sharp punctures, somewhere between spongiform and massive scales in each case, and are far, far more vulnerable to abrasion than both. They have none of the camouflaging qualities of spongiforms, and share an inability to release water with massives. Nonetheless, they have some unique advantages compared to the other scale types. One in particular is that individuals primarily covered in stratified scales have no need to go through painful molting periods, since old outer layers of scales will dry and flake off continuously if left alone. In practice, as this continuous shedding is often considered unpleasant or unsanitary and since the presence of very old layers reduces the visual appeal of their scales, lustrous individuals require regular grooming (in the form of careful brushing or scraping actions) and baths in order to maintain their appearance.
This constant shedding of keratin layers also has a hygienic effect. The other two scale types provide a relatively stable habitat for parasites and microbes, and while periodic moulting limits the time a given layer of scales can be infested before being removed, the interval may be long enough for such organisms to make their way deeper into the skin. Stratified scales, with their constant renewal of layers, are a far more difficult environment for the same organisms, since each layer is a barrier to infection and must be penetrated within the time that it takes for a layer to be shed. Although there are other paths to disease, individuals with this scale type are not frequently subject to infections via the skin except though wounds or physical removal of the scales.
Although there are common stereotypes associated with each scale type, those linked to stratified scales are the strongest. Due to their grooming habits, their resistance to certain diseases, and their distinctive appearance, takmar of this type are frequently seen as being clean, healthy, long-lived, and attractive, and therefore prized as mates (often even more so because of their rarity). On the other hand, they may also be seen as self-absorbed, fastidious or prissy to the point of obsession, high-maintenance, and because of the low tolerance of their scales to wear, also as fragile, unsuited to menial labor, and overly sensitive.
Takma scales are formed in tiny nodules from the remains of epidermal cells, which leave keratin behind when they die. The keratin accumulates in one of two patterns, one for stratified scales and one for the other two scale types listed above.
In the vast majority of individuals – those who have spongiform or massive scales – the accumulations form relatively thick, unified layers that for the most part are internally undifferentiated. Newly grown scales of these types result in colors that are at their most vibrant; spongiform scales lend a bright, vivid blue hue, while massive scales are at their most translucent. As the scales thicken and age, they dry out and gradually become dull and clouded, resulting in a muted, almost gray color and brittle, papery texture.
As the scales approach the end of their useful life, the growth of the keratin layer is interrupted, and the formation of a new layer subsequently begun beneath it. The discontinuity between the two layers provides a weak point at which the old layer can be sloughed off, aided by the production of enzymes that further decay the bonds between the two layers. Although the shedding events take place in the same general period of time (a “moult”), the entire layer of scales is not shed at once; it comes off in patches.
When the old layer is ready to be shed, the takma, responding to an “itchy” feeling in the affected area, will pick or scrape at the old scales to remove them. Even with relative care, this can be a mildly painful process, as the skin underneath can be quite sensitive. The length of time it takes for scales to require shedding and replacement varies strongly with the growth rate and physiological state of the individual.
This is most obviously expressed in the frequent moulting of pre-adult takmar, who due to their rapid growth may shed scales every ten or twelve vigils or less. The moulting cycle lengthens as an individual approaches their adult size, generally stabilizing at once every one or two turns; this is because the individual no longer requires a new keratin layer to accommodate its growth, but rather to ensure that the scale layer remains flexible and does not become host to diseases or parasites. In these normal moulting cycles, the layer is generally shed in patches beginning on the face and head and gradually moving toward the tip of the tail.
Non-growth-related increases in body size, too, such as pregnancy or obesity, will trigger shedding events in mature individuals. Old, sick, or stressed individuals may also shed more frequently, and sometimes prematurely, with patches being shed outside of the usual order.
Although the basic mechanism of scale production is the same for stratified scales as with the other types, the key difference is the length of time taken to produce a layer. Each scale forms a keratinous layer over a fairly short period, no more than once every few vigils, and each layer is correspondingly thin. Because it takes any such sheet approximately the same amount of time to flake off after formation as it would with the other scale types, however, the scales are ultimately composed of many sheets layered atop one another.
When the time comes for the outermost sheet to flake off, it often does so without intervention by the takma, due to the fragility and lightness of the sheet. Because it is also not directly in contact with the epidermis, little or no discomfort is experienced, as the layers below continue to provide protection. Scales are shed in approximately the same head-to-tail sequence as with the other scale types, but in practice any pattern is difficult to observe. The lightness and fragility of individual scale layers means that premature shedding is frequent; in addition, the only visible evidence of shedding is the detritus of discarded scales an individual leaves behind.
The takmoids, a clade of species to which takmar belong, have played host to a variety of scale types over the past several hundred thousand cycles, present in varying amounts in different lineages. Of these, at least two were passed on to the earliest takmids, living about 91,000 cycles (492,000 Earth years) ago: massive and cavitated, this last consisting of scales whose microstructure is embedded with numerous, nanoscale-sized spherical “bubbles”.
After a relatively short time, by 74,000 cycles (400,000 years) ago, the takmids had begun to split into two lineages: the dvidalins, who remained in the original takmid habitat of what is now the Seas of Grass, and the takmins, who had successfully colonized what is now the Brightness. The takmins (represented almost entirely by the pre-takmar) had never had a high incidence of cavitated scales, and over time saw fewer and fewer individuals with them or with the characteristic blue tint they provided. Although the genes for cavitated scales remained, and continued to be expressed as display markings and more rarely as the primary scale type, massive scales became by far the dominant type.
By 52,000 cycles (281,000 years) ago, stratified scales appeared as a mutation of massive scales. Although less durable than massive scales, a very small proportion of the population had them as their primary scale type, due to the health benefits they conveyed. Cavitated scales had almost disappeared by this time, restricted almost entirely to riverside populations, and in the process of being replaced by the spongiform scale type; though visually similar in its effects and based on a mutation of the same genes as cavitated scales, their microscopic structure was different.
The situation remained stable until the drying of the Brightness, beginning 18,000 cycles (100,000 years) ago. The divergence of the riverbank-dwelling proto-takmar and the more inland proto-xtauh included a slow decrease in the number of primarily spongiform individuals among the latter, while it began to (very slowly) increase in the other. But when around 15,000 cycles (81,000 years) ago the proto-takmar began to migrate into the Cerulean Tangle, selective pressures there more dramatically favored spongiform scales, while those in the Brightness favored massive scales.
While proto-takmar continued to migrate from the Brightness to the Tangle in successive waves, periodically renewing the genes for massive scales, after the end of the migrations in about 6,000 cycles (32,500 years) ago spongiform began to dominate the mix of the now separate takma species. Although stratified scales remained relatively rare, their frequency increased as well, as the intensively organic rainforest environment hosted far more parasites and diseases that the scale type would prove an effective barrier against.
The perceived color of any given area of a takma’s body depends on characteristics of each component of the skin. The base color is provided by the epidermis, which, as mentioned previously, contains two types of pigment. One, xanthochrome, a type of xanthophyll, is yellowish in color, but in different concentrations results in hues from very pale yellow to a yellowish brown; the other, erythrochrome, a type of carotene, is reddish but varies by concentration between a pale pink and a dark, rosy color. Various combinations of these pigments results in oranges and dark reddish-browns.
The pigmented epidermis may or may not have its perceived color modified by the overlying scales. Although scales contain little or no pigments, their microscopic structure may nonetheless selectively reflect back light in a manner that combines with, and alters, the colors showing through the scales from the underlying skin. This is the case with both spongiform and stratified scales; the former preferentially scatters light so as to appear blue, and transforms the individual's perceived color to a range of greens, blues, and purples, while the latter overlays the skin color with a pearly or semi-metallic sheen. Massive scales, by contrast, are nearly transparent and with a relatively matte surface, and produce little to no color modification.
Scales vary widely in size, from several millimeters or less over most of the body, to several centimeters across, particularly on parts of the body that demand additional protection, such as the head, spine, and parts of the face.
Work in progress
Although males and females have approximately the same possible range of colors, their distribution on the body is different. Males are more likely to have simple color schemes on the main trunk of the body: frequently it is a simple color gradient, a darker shade on the dorsal surfaces fading to a lighter shade on the ventral ones. The main exception to this are the wings, the dorsal surfaces of which are often adorned with highly visible patterns, which may be composed of contrasts between different shades or (more rarely) with different colors.
Females, on the other hand, tend toward more complicated coloration, though it is very rare (though not completely unknown) to have more than three colors: a primary body color, the color of the stripes, and the pattern color.
Almost all females bear a series of stripes along their dorsal surfaces, each running across the spine and down toward the sides. Most frequently these are a very dark brown-to-olive in color, though they have been known to occur in other colors darker than the primary body color. Females are, indeed, generally more likely to bear multiple colors, though one is almost always predominant, with the others appearing in patterns of markings (aside, usually on the head, face, neck, and throat; the flanks and hips; or, less frequently, the sides of the ribs.