So, if we were to treat realistic creature design like making a pokémon card, one of the obvious "types" would be volant (flight-capable) creatures, and their biggest downside would be the fact that around 25-20% of their body mass has to be the flight muscles, leaving little room for other things.

This is a problem. Just as legs become dead-weight in flight, flight muscles become dead-weight on land. The best way to counter this is to find as many uses for them as possible.

So, I thought to myself "If it already is around the most vital organs, why not make it more bullet resistant?"

The idea is to enhance the muscle fibers to be more durable without diminishing force-generating capacity, but at the expense of the energy and time it takes for the flier develop them. I mean, dragons already have long lives, might as well make use of it.

But I don't know if that's possible. We most likely want to modify the motor protein itself to have a better shock resistance and tensile strength. Would such modification be possible?

  • $\begingroup$ Oh, yeah. I keep forgetting that science-based hammer. Meph, let me know if you substantially disagree with this being a duplicate and I'll un-vote. It seems to me the two questions are fundamentally identical. You might also want to peek at this Q. It's not a duplicate but might yield an interesting nugget or two. You might want to look at this one, too. $\endgroup$
    – JBH
    Nov 17, 2020 at 0:20
  • $\begingroup$ @JBH Zat question was not about modifying ze motor protein! It's entirely different! $\endgroup$ Nov 17, 2020 at 0:30
  • $\begingroup$ No, it's not entirely different. The results are the same and at least one of those answers points out the problem can't be solved by the muscle fibers at all. Worse, modifying the protein won't solve your problem (that's one of the reasons why the other question is so valuable). I'll retract my vote so that others can chime in on whether or not that question and yours are, indeed, different. But I don't think they are. $\endgroup$
    – JBH
    Nov 17, 2020 at 0:35
  • $\begingroup$ I think @JBH is correct. Both questions are about muscles with higher tensile strength. Each question has different reasons for doing this, but the answers should be the same. $\endgroup$ Nov 17, 2020 at 1:40
  • 1
    $\begingroup$ @JustSnilloc It's a last resort, when the dedicated tissues have already been breached. $\endgroup$ Dec 17, 2020 at 17:03

1 Answer 1


It is not the motor protein that defines muscle cell resistance to piercing, but the cell's envelope - lipids ("fats"). Tensile strength of that envelope is almost the same for all living organisms - about 100 kN/cm. Coincidentally the same as for steel; and it can't be increased significantly.

But why are we not as hard as steel? Because we are multicellular organisms. And connections between cells are much weaker than cells themselves. When a knife cuts through flesh, cells remain intact (mostly), just get separated. So by increasing inter-cellular connections, muscles may become more resistant to cutting (tendons do this, for example).

But bullets have enough energy and impulse to destroy individual cells on its path. So this question is similar to "how to make bulletproof mail". The best answer is to add some bulletproof plates on top or under it. But that clearly is not the answer you want.

So the only thing I can suggest here, is to make muscle cells as small as they can be. This will exchange motor protein for more envelopes. This will greatly reduce muscle strength and mobility, but would make it harder to penetrate. This "shield muscle" will not be able to stop direct hit from AK from close distance, but might be able to hold high-caliber, low-speed handgun bullets fired from ground to sky.

But it would be much better and logical to use some keratin/bone structures for protection.

  • 1
    $\begingroup$ So, I would have to amp up the strength of collagen $\endgroup$ Nov 17, 2020 at 11:02
  • $\begingroup$ the other reason we are not as strong as steel in a cell membrane is only a few molecules thick, a steel foam of the same density would tear like paper. in inch thick layer of muscle there might only be a mm of cell membrane and matrix. $\endgroup$
    – John
    Dec 17, 2020 at 15:28
  • $\begingroup$ @Mephistopheles collagen is already 6-7 times stronger than steel. $\endgroup$
    – John
    Dec 17, 2020 at 15:30
  • $\begingroup$ @John, the metal foams (i.e. titan foam) are quite strong and light meterials used in planes and rockets. They are just too expensive to produce en-mass. $\endgroup$
    – ksbes
    Dec 24, 2020 at 10:21
  • $\begingroup$ @ksbes the foam you are referring too is much much denser that the foam you would get, titan foams come out around 50% porosity, while a cell membrane foam would be closer to 95% porosity or higher. $\endgroup$
    – John
    Dec 24, 2020 at 14:37

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