If a humanoid species of what are essentially people covered in chitin, how would they color themselves in the way we get tattoos? I considered the idea of etching or carving, but that wouldn't leave much room for color. Some parameters for this is that the armor is rather thick, 3 inches in some cases, and there is plenty of technology available to this species that's beyond modern technology.

In summary, without cutting into the chitin (for structural and decorative reasons), how could an advanced race of crab-like humanoids give themselves permanent tattoos?

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    $\begingroup$ But.. you can stain chitin with different colors... did you do any research? $\endgroup$
    – Aify
    Feb 25, 2018 at 19:23
  • $\begingroup$ Wait seriously? I honestly had no idea. $\endgroup$
    – Ely Miller
    Feb 25, 2018 at 19:35
  • 2
    $\begingroup$ sciencing.com/stain-chitin-8123067.html $\endgroup$
    – Aify
    Feb 25, 2018 at 19:42
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    $\begingroup$ considering how chitin is shed there is very little you could do that would be permanent. No matter what you do it will be lost with the next molt. $\endgroup$
    – John
    Feb 26, 2018 at 4:25
  • 2
    $\begingroup$ Strongly related: How would tattoos fare on reptilian scales? $\endgroup$
    – Mołot
    Feb 26, 2018 at 8:49

7 Answers 7


You could use inlays.

silver inlay shield


Inlay covers a range of techniques in sculpture and the decorative arts for inserting pieces of contrasting, often coloured materials into depressions in a base object to form ornament or pictures that normally are flush with the matrix. A great range of materials have been used both for the base or matrix and for the inlays inserted into it. Inlay is commonly used in the production of decorative furniture, where pieces of coloured wood, precious metals or even diamonds are inserted into the surface of the carcass using various matrices including clearcoats and varnishes.

For your creatures, they would scratch or engrave a depression in their chitin armor. Then a piece of metal or shell cut to fit exactly would be pressed in / glued in and lacquered over.

Humans have been decorating their hard teeth this way for a long time.

teeth with jewel inlays https://news.nationalgeographic.com/news/2009/05/090518-jeweled-teeth-picture.html


I'm promoting the Chitin version of wood burning. I'm thinking about the beautiful Maori tatoos which, anciently and usually during modern times, does not apply color. It's all about the pattern, and the burn can be almost vanishingly thin, protecting the Chitin, and remarkably precise for crisp, clean lines. Wood burning would be more like our tatoos that are near the surface of the skin.

Besides, Maori tatoos would look smokin' on crabs.

enter image description here

  • 4
    $\begingroup$ For some reason, I think that those tattooed crabs would look very shiny. $\endgroup$
    – Cort Ammon
    Feb 26, 2018 at 3:34
  • $\begingroup$ And their tattoos could be a record of all the victories they win $\endgroup$
    – Pliny
    Mar 13, 2018 at 13:43


These are artworks made from assembling small, colourful pieces of stone or glass (known as tesserae) into a beautiful whole. The other required items are a surface (the chitin) and strong gum or glue (which the modern tech specified in question can definitely provide).

This artform was known to the ancients and was widely used to decorate religious structures.

Golden Mosaics of Great Mosque in Corduba


With their fancy tech and the desire to decorate themselves without cutting their chitin they have indelible ink which doesn't wash off.

Alternatively another technique we use is to paint or draw a picture on a medium and then varnish over it for protection. If they spent as much resources as we do on makeup invention etc,. they'd have it sorted. In fact varnishing adds depth and texture to drawings so would be great.

Lastly and most impressive would be along the lines of resin carving or lacquer where layers are built up, then carved fancifully and artistically into low relief or full round works of art.


...an advanced race...

By advanced, I understanding at least matching our technology level, right?

They could use lasers to mark a very thin layer of their chitin, forming patterns or images. This is used in our own world to draw on wood, denim, plastics and other things. It wouldn't be a stretch for a chitinous creature to use this for a "laser tattoo".

This is different from wood burning in a few ways:

  • It uses coherent light rather than a hot object to cause color changes;
  • Due to that, it is possible to burn layers of chitin that are beneath the most external one, by using wavelengths for which the chitin is transparent;
  • Lasers can also cause color changes through ablation or photolysis, which means more visual effects are available with them;
  • Lasers also allow for more precision, so more detailed images or patterns may be printed on the target surface.

No, you're not going to get tattoos as we currently (kind of) understand them, but since you opened it up to other forms of advanced technology, I'd suggest cells or protein nano-machines.

The first thing to understand is how tattoos work in mammals:

  1. We have skin cells that produce melanin in response to UV exposure. This prevents UV radiation from penetrating deeper into our skin.
  2. Over time, most of the melanin fades, but some of it is absorbed by specialized immune cells.
  3. These immune cells hang out in the skin with their melanin, providing some protection from UV's.
  4. When they die, another immune cell of the same type absorbs the melanin to keep doing the job of protecting from UV's, usually in roughly the same place as the previous cell.

Tattoos are a hack of this system. They introduce tattoo ink under the skin, and the immune cells think it's melanin and absorb it. (The life and death cycle of these cells could explain why tattoos fade and migrate over time, but that's an answer for a different question.)

You can watch more about this here:


In contrast to self-contained cells in the sin, chitin is more like a biologically-produced mineral.


Like many minerals, it has a specific porosity. It's used as a cell wall by some fungi, and this is how microbiologists discovered that they could stain it. The stain enters the "pores" of the chitin and binds to specific molecular points. This is similar to writing on your hand with a permanent marker.

The problems with microbiological stains are that they can be dissolved in the appropriate solvent, or, in living creatures, wear off over time as biological material is replaced.

So what if your crab-men reverse engineered the cells that contain the tattoo ink? So instead of needles injecting ink, the needles inject the cells or other proteins that contain the ink. This could be done while the chitin is soft, just after a molt.

The cultural questions I can imagine this leading to are, how did your crab-men discover the immune cells, and why did they adopt the practice of tattooing themselves with it?


They could apply some sort of durable (plastic?) film on the chitin, with the image printed on it beforehand. This film could have some sort of glue layer to make it stick.


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