When shapeshifters meet each other in other societies, whether human or not, I was thinking that they could "sense" each other's "true identity". They "just know" that the other is "one of us".

How about within their own society?

Everybody know that the others are "one of us" (OF COURSE!), so what?

What if someone choose to stay in other shape other than himself/herself?

How can the others know that "He is Bob, she is Mary"?

I had thought they could have some kind of "telepathic" power that can tell each other apart, but that's essentially giving them "another superpower", and it's way too convenient.

Is there any other reasonable way for them to tell each other apart?

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    $\begingroup$ Do you want a "natural" way for the shapeshifters to sense other shapeshifters or something manufactured by them? Also, when you say "shapeshifter", can you specify what they can actually do? Werewolves are shapeshifters but they (usually) have two forms - human and other (frequently a man-wolf hybrid form but sometimes it's just a wolf). Neither of the forms will look identical to another werewolf's. And even shapeshifters that can take on any form might not do a perfect copy - they might have one wolf form, one cat form, one human form, etc but each is still distinct. $\endgroup$
    – VLAZ
    Commented Jan 2, 2020 at 21:59
  • $\begingroup$ Any way would do, as long as it helps themselves to distinguish each other. What I have in mind is the kind that could take on any forms, much like Mystique could do, though I don't know if she could take on any non-human forms. $\endgroup$ Commented Jan 3, 2020 at 2:58
  • $\begingroup$ Whenever I think of shapeshifters I think of the Founders. This question would seem especially applicable to a race whose native form isn't even a solid. $\endgroup$
    – Michael
    Commented Jan 3, 2020 at 21:13
  • $\begingroup$ Why do shapeshifters need to tell one another apart? $\endgroup$
    – Kaia Leahy
    Commented Jan 5, 2020 at 15:42
  • $\begingroup$ So Bob can know who his wife is!? XP I don't know, this seems to be judging things from "human standard", but unless your setup is like what @Renan suggested, it would be nice to know "who you're talking to", at least for your own kind, don't you think!? $\endgroup$ Commented Jan 6, 2020 at 10:17

9 Answers 9


Scent would seem to be an obvious but non-superpowered way of identifying other shapeshifters. Vocalisations that are inaudible to most other listeners might also work... ultrasonics, for example. By way of a bonus, both approaches might cause animals (or even children with better hearing than adults) in the presence of shapeshifters to become agitated, if you wanted that sort of thing.

I seem to recall that Pratchett's shapeshifters (or at least, his Discworld deities who could assume any form they wished) were not able to alter their eyes, so perhaps there might be other subtle tells that could be spotted by an alert observer. Your example of gaydar is interesting, because that often relies on subtle cultural clues... bodylanguage, clothing, hair and makeup styles (or the lack thereof), idiomatic language and so on. Such things can be quite obvious to anyone who has come across them before, but others can be quite subtle and non-group members might simply ignore them as being uninteresting or irrelevant. The set of tells is likely to be like a language or dialect, rather than a universal property across the species... not every shapeshifter may notice or understand the tells of every other member of their species. Note that there are humans who have no faculty of gaydar and for one reason or another are oblivious to some or more social cues of this type.

As a last resort, there's always the hard way, as exhibited by this unusually safe-for-work Oglaf. (If you're not familiar with Oglaf, by the way, you probably shouldn't browse around it from work, even though this specific example is entirely clean much of the rest of their work is NSFW)

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    $\begingroup$ to add to your answer, another option is seeing into the UV range and shapeshifters dont have the skin blemishes (that are only visible in the UV range) that humans have, here is an example $\endgroup$
    – Nullman
    Commented Jan 5, 2020 at 12:42
  • $\begingroup$ @Nullman UV vision is a suprisingly awkward thing... quite a lot of the stuff you want to make your optical elements out of is wholly or partially opaque to it, and if you do have a lens that lets in both UV and visible light you'll have a job focussing both of them at once onto your retina. You'd probably need all sorts of other weird things, like UV-filtering nictitating membranes, or something. Gets complex fast! $\endgroup$ Commented Jan 5, 2020 at 12:59
  • $\begingroup$ several animal species can actually see in the UV range, like reindeer. I think it actually adds interesting complexity because some one could pretend to be a shifter by applying sunscreen $\endgroup$
    – Nullman
    Commented Jan 5, 2020 at 14:35
  • $\begingroup$ @Nullman the ability to see UV and the ability to resolve detail in UV are two very different things. The visual capabilities of mammalian prey species are surprisingly poor, too. Seeing UV blobs is not the same as seeing fine patterns on something as small as a human face, and being able to clearly distinguish those patterns. You'll also have serious problems trying to see UV patterns on people with reasonable amounts of melanin in their skin... $\endgroup$ Commented Jan 5, 2020 at 14:39

I am autistic and have a condition called "face blindness". I'll start with that, and add a few other things.

Because I can't easily distinguish people by their faces, I take note of mannerisms such as how they sit, how they stand, how they walk, how they wear their hair and even smell (I have an overly sensitive sense of smell.)

Combine this with something common in humans: A greater ease to distinguish between members of their own races, and similar ethnic groups. This goes all ways. Asians can easily identify other Asian ethnic groups. Japanese can readily identify other Japanese, Koreans and Chinese, for example.

French, Germans and Russians, for example, can tell each other apart by features that are easily identifiable by people familiar with an ethnic group.

So, if you combine my techniques for identifying people along with your changelings having some specific feature that they use to identify each other, but not easily recognizable by humans, you are in business.

  • $\begingroup$ anecdote: My Taiwanese friend said, “Korean?” and the girl responded “No, Japanese.” My friend then said, “Oh, you look Korean.” $\endgroup$
    – WGroleau
    Commented Jan 3, 2020 at 17:59

They don't, often with hilarious results.

This is coming from a NSFW comic, so I am not linking to the original. It's name is Oglaf, if you are willing to look it up in Google.
Source: a usually NSFW comic called Oglaf.

Think of it: shapeshifters are not human, so their society does not have to work by human standards. If you look at social insects, fish pods, portuguese man-o-wars and corporations, you will see that they are examples of societies where what matters is one's function within it, not one's identity.

It may be that shapeshifters infiltrate human societies, and learn how to "be a human" in order to survive, either because they prey on humans or because they are under some kind of threat. But the very concept of identity might be unnatural and more like a learned behavior for them. This will be specially true if they are not true social beings, but rather a species that is transitioning from a solitary lifestyle to a communal one via evolution.

A real life analogue would be myrmarachne spiders:

A spider that mimics ants in form
Source: see link above.

In the picture above you see Shaun. Shaun doesn't hang around much with other spiders of his species. Last week Shaun had a one-night stand with Jane, a female myrmarachne that he met through a dating app. To be fair he couldn't tell the difference between Jane and any other female myrmarachne to save his life, but she was the nearest one he could find and so was him to her. Shaun will probably never meet Jane again but that doesn't matter - his offspring will thrive, feeding upon unsuspecting ants.

Granted, Shaun cannot shapeshift, but we know that if he could he would still be just as antisocial.

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    $\begingroup$ +1 for including corporations, a much-overlooked sentient non-human species. $\endgroup$
    – Criggie
    Commented Jan 2, 2020 at 22:33
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    $\begingroup$ All we know is that we've never caught Shaun changing his shape. And now I will have nightmares of shapeshifting spiders for a week... $\endgroup$
    – GreySage
    Commented Jan 3, 2020 at 21:47

How do you distinguish between identical twins?

If you know them well, you just know. It's really hard to pin it down to something you can describe, maybe it's a facial expression, a mannerism, a tiny distinguishing feature, the way they move, something in the tone of voice. There are many things we use to tell people apart, crude matters of primary appearance are only on the surface.

You can probably identify a family member just by the way they greet you on the phone. I regularly have to play guess the family member when someone sends me a message from an international burner phone which comes from only the way they type and what they say (for some reason they all assume I have the number already somehow).

Since they're shape shifters, they won't consider primary appearances, it'll be all these secondary factors that come into play. They will know that that's Bob's walk, and that's Mary's phrasing and accent.


Shapeshifters do not have the same rods and cones in their eyes that we do. We as humans see a limited selection of color, from just above infrared to just below ultraviolet, through a filter of red, green, and blue light. Shapeshifters, however, can see beyond that, into ultraviolet and infrared, and in far greater scope than just three colors. Their abilities aren't perfect; while they may look like a human to a human, to another shapeshifter they are covered in stripes, swirls, dots, and blotches of color.

Just like a black-and-white picture hides the colors of the actual scene, our eyes hide the colors we can't perceive - and the shapeshifters use those specific colors to tell each other apart: Alice has a gred squiggle on her arms, Bob has blurple stripes on his face, and Claire's legs are entirely bleen - though to human eyes, Alice looks ordinary-human-pale, Bob looks ordinary-human-tanned, and Claire seems to be ordinary-human-dark-skinned.

Certain creatures, notably the mantis shrimp, can see the shapeshifters' true colors, but can't (or won't) mention the visual difference.

Additionally, as Mark Storer mentioned in his comment, the shapeshifters may have (replacing or in addition to extra light sense) polarized skin tones. While sunglasses would pick up linear polarization, they wouldn't detect circular polarization - though 3D movie glasses would. Linear polarization may be picked up by reflection, too, so it makes sense for the shapeshifters to have circular polarization. The polarization filters would likely be a key part of the creatures' ability to shapeshift, as it would control color and brightness.

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    $\begingroup$ In a similar vein, light might polarize differently when it reflects off them, and given the ability to see polarized light, could distinguish. Of course that means you just have to throw on a pair of high-end sunglasses to spot something off... "They Live" all over again. "What's the matter baby?" $\endgroup$ Commented Jan 3, 2020 at 19:06
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    $\begingroup$ @MarkStorer Imagine living amonst humans for thousands of years, until someone invents 3D movies and circular polarization, and suddenly it's possible for everyone can see you! It's like a reverse horror movie! $\endgroup$
    – ArmanX
    Commented Jan 3, 2020 at 20:22

One theory about why mimicking songbirds do so, is because that the females judge a mate's fitness based on the number of different songs he can portray; copying other birds is a quick way to learn many distinct songs.

So, maybe it isn't so much that shapeshifters recognise each other while "in character", so much as they change into character in front of their potential mates, to demonstrate their prowess. Maybe they mimick characters they have met, characters they both know well, or a character they have just killed to feed their mate and show their shapeshifting prowess.

Or maybe it isn't the character itself that impresses the mate, so much as the bounty the shapeshifter can steal while in character (whether it is jewels or corpses), with the shapeshifter returning to the mate after each short adventure to show their gains.

Either way, it isn't that the shapeshifters recognises each other while in character, so much as the shapeshifter shows the transformation to another shapeshifter to impress them.


If not telepathy then a kind of mind meld through physical contact. Consider how Odo and the lead Founder played by Salome Jens share the Link in Star Trek: Deep Space Nine.

By being in physical contact and "initiating a connection", which I tend to imagine - from a consciousness perspective - like simply relaxing or allowing thought or emotion to transfer, the two can know each others thoughts and experiences. Assuming most individual's experiences are unique, or even by seeing one's self in a specific memory of another, it would be possible to know who the other is in the meld. Contrary to "allowing" such a connection, one might also resist. Consciously this might mean attempting to think of nothing, restricting ones thoughts, or, with more acute, biological control, it could mean sensing which parts of one's self are in contact with which parts of the other and suppressing the responses of ones neurons at the interface between the two organisms ( supposing such organisms have a kind of nervous system as we understand it ). The latter of course would allow the individual to simply block a connection, or otherwise allow it, without so much effort of focus and concentration ( supposing also that beings such as this would perhaps evolve and develop these kinds of mental "muscle memory" specifically for such critical tasks ).

Of course for practical purposes individuals of a social species begin to learn a concept of individuality from a young age, and the distinguishing features of one's personality or (chosen) personal appearance would serve to reduce the effort needed to identify other members, but perhaps at the additional cost of maintaining such individualistic traits. But again, with practice things become second nature as suggested above with the handling of consent during mind meld.


They use a secret language

The shapeshifters don't have a natural built-in way to tell each other apart but they've come up with a cant they can use.

A historical example of this concept is Polari - it was used in some criminal circles as well as the LGBT community. At the time they were basically the same, as being homosexual was a punishable offence. So, LGBT people would use Polari to safely distinguish each other - say, a gay man would drop some words in Polari in a casual conversation, even in a crowd. If the other party picked up on it, then they can more safely converse later.

Polari words are plausible deniable - it's composed of slang and words taken from other languages, so it's pretty much "safe" to sprinkle few in a sentence. Most people will just ignore the words but if confronted, it's easy to just say "oh, it's Italian" (or whatever).

Furthermore, Polari was really hard to study as an outsider. It was a very fluid and dynamic language, so people who mainly mingle in crowds who spoke Polari would be able to keep up.

So, shapeshifters could similarly have their own type of language that reasonably "mimicks" human language(s). It will be rather on-point for them to do that.

  • It helps with hiding in plain sight - they can discuss internal matters in their own cryptolect, even among other people.
  • It can help verify other shapeshifters. There can be many potential tells that one is a shapeshifter - body language, how one acts, where one is, etc. but you can never be too sure. Pulling somebody aside and going "Hello, shapeshifting brother of mine" only to be met with "WHAT?" is not a very good way to stay secret for long. And cleaning up such "leaks" tends to be messy.

Shapeshifters may even have an extra advantage of being able to use language no human could. By manifesting vocal organs or muscles that humans don't have, they can employ vocalisation or expressions/body language no human can fake.

It's also not hard to keep the language fluid. Existing languages already have linguistic drift and languages used within groups are especially prone to change a lot in a short span of time. Think of how teenagers communicate or memes - without keeping up, you can be left behind and these means of communication don't even have it as a purpose to be deliberately opaque for outsiders.


I would say there are many biological senses that could help a shapeshifting species pick each other out of a crowd. Sent and pheromones have been mentioned but here is one that might better fit the “sense” you mentioned. Sharks have a sixth sense that detects the electricity given of by nerve impulses, and electric eels actually send a tiny electric pulses like radar to try and find food in murky water. This could be an easy way for any shapeshifter to figure out who is who.

Also I can easily imagine them developing a “spy” culture. Like how cold war spies interact with each other, with code phrases and cloak and dagger meetings, it would make sense because their natural habitat is literally, “being under cover.” It’s easy to say how Identity may be an alien concept to them, but the more you study and observe a species, the more of what makes them tick sinks in. Like Steve Ervin with crocodiles. Not to mention as an autistic, I’ve honestly felt like an alien studying humans. So I will say you are a confusing bunch as a species, but that is what makes you so fascinating.


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