These questions are a sort of follow up of my question about white pupils. I'm designing some other creatures whose defining traits involve "weird" eyes:

  • How would a creature with oddly shaped pupils see? Like I'm not just talking about slit-shaped or oval-shaped pupils--I'm talking about things like diamond-shaped, star-shaped, or even cross-shaped. Do the shape of the pupils affect how much the creature can see?
  • What are the effects of polycoria in an organism? I've heard that in most cases of polycoria double vision can occur. If a creature were to have, say, three equally shaped pupils, would this produce the same effect? Would it even have a sort of "compound eye" effect if there were more pupils?
  • Could a creature have multiple irises or a multicolored iris? This creature in question could have "layered" irises (so that it looks like they're rings circling the pupil) that it could use to rapidly alternate eye colors to intimidate threats, but I'm also pondering whether this could be achieved with a single, complex iris. Would either method work, and if so, would this affect the eyes' basic function in any way?
  • $\begingroup$ I would offer the example of my own grandmother. She was a test subject for early vision repair surgery, and as a result had one eye with a square pupil when it was fully contracted - it appeared mostly normal when open. As long as the pupil reduces intensity sufficiently to avoid retina damage and still channels light to the right places, I think anything goes. $\endgroup$
    – user8827
    Commented Apr 19, 2015 at 16:09

1 Answer 1


There are a variety of pupil-shapes in real animals, so I would look at some of these for ideas about how to make your creatures more realistic.

Besides slits and ovals, which indeed seem to be the most common pupil shapes, animals can have horizontal rectangular or somewhat hourglass-shaped pupils, or in the case of some geckos "stenopeic" pupils that are like a combination of a slit and a pinhole pupil. I found this web page about strange animal pupils like these: Strange Pupils. I also found another good article: this one mentions that some species of cuttlefish have W-shaped pupils.

Multiple irises might be possible I suppose, but it seems a little useless overall. What would be the function? It seems like it might be simpler to get the same appearance from a single iris with ring-shaped patterns of coloration on it.

  • $\begingroup$ Good point about the irises--I'd originally thought multiple irises might've enabled the creature to rapidly change their colors to intimidate others, but now that you mention it this could be performed with just a single complex iris; I'll change the description accordingly. Thanks! $\endgroup$
    – Hawkpelt
    Commented Apr 18, 2015 at 18:41

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