This question has two parts:

  1. Could biological processes create an organism than can see in wavelengths outside the human-visible spectrum? ("Outside" meaning some significant amount outside. There are known organisms on Earth than can see in near-infrared or near-ultraviolet, but that's not I'm asking about.)
  2. What factors might cause such a creature to evolve?

For the context of this question, "see" means an ability to sense the world in a similar level of detail to human sight, using electromagnetic waves.

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    $\begingroup$ I assume you mean outside the human-visible spectrum? The "visible spectrum" was defined by humans, after all. $\endgroup$ – Frostfyre Jul 13 '15 at 4:39
  • $\begingroup$ @Frostfyre: Yes, human visible. I edited the question to clarify. $\endgroup$ – ItsTimmy Jul 13 '15 at 4:42
  • $\begingroup$ Related: whyevolutionistrue.wordpress.com/2013/03/08/… $\endgroup$ – yshavit Jul 13 '15 at 5:34
  • $\begingroup$ As long as the energy of the photon do not destroy the retina or any form of photo receptor and provided its wavelength do not allow it to penetrate the eyes anything goes. However most animals don't produce high freq em wave like gamma ray or x-ray(hulk & superman don't count) or low freq em wave microwave or radiowave therefore you might need more effort to persuade and convince evolution. $\endgroup$ – user6760 Jul 13 '15 at 6:44
  • $\begingroup$ An interesting Q! Around our visible spectrum the optical lenses can focusing pictures on a plane, but in other spectra other solutions must be used that may be "less biological"? And is it a coincidence that our spectra has the width of one octave, where deep red looks similar to high violet? $\endgroup$ – Lehs Jul 13 '15 at 11:01

There are several problems to overcome for a much wider range of wavelengths (and I don't know a solution, so I'll just list these):

The sun will have to produce light in those wavelengths, otherwise you may be able to see them but it will be dark;

Ultraviolet and shorter wavelengths are ionizing, meaning they cause chemical changes (damage). Think sunburn to much more damage at shorter wavelengths. In a world that doesn't protect against this kind of light, life is unlikely to arise at all, and whatever does arise will want to protect against this, not use it to see.

Water is very absorbant in most of the infrared region, and eyes contain lots of water making them non-transparent. The sensitive parts would have to be immediately on the outside of the skin, and the atmosphere shouldn't hold much water.

At much longer wavelengths (like radio), you also need equally long antennas to detect them. Getting any kind of resolution would need eyes the size of radio telescopes (eyes would be radio telescopes).

Finally, you have to consider whether the kind of thing you want to see is actually opaque at a given wavelength.

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    $\begingroup$ " will want to protect against this, not use it to see." It's not a given that these two are in opposistion. At the very least you could have organs that are more exposed than the rest of the body and accept the need for repairs in exchange for the ability to sense. (Of course this does not explain how life evolved in such a hostile environment in the first place) $\endgroup$ – Taemyr Jul 13 '15 at 9:17
  • $\begingroup$ I like the part about how, to detect radio waves, they would need an antenna. This is kind of an interesting idea for an alien... Maybe their 'sight' with their antenna isn't as detailed as ours and isn't their primary sense... $\endgroup$ – ItsTimmy Jul 13 '15 at 18:28
  • $\begingroup$ I don't agree with this being the accepted answer, it seems to ignore the fact that most life on earth sees in different bands than we do. $\endgroup$ – Darren Ringer Jul 13 '15 at 22:02
  • $\begingroup$ also you don't need that antenna to be protruding, you only need it to be certain lengths. That length can be coiled or packed tightly together to take up less space. Maybe it could be part of the nervous system of the animals body. Most small mammals nervous systems have more than enough nerve length in their bodies to accommodate the lengths required for this. There is even speculation that migrating animal may use an adaptation like this to help them navigate. $\endgroup$ – Code Uniquely Jul 14 '15 at 3:51
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    $\begingroup$ @DarrenRinger I mentioned in my original question that I am more interested in wavelengths far outside of our visible range. The animals on Earth that see in other wavelengths generally see with infrared or ultraviolet, which is closer to our visible spectrum than, for example, radio waves. The other answers which do mention these Earth animals, while still high-quality answers, fail to mention these further regions of the spectrum. $\endgroup$ – ItsTimmy Jul 15 '15 at 19:51

In principle

However there is some limitations. You need something to see. This image shows the absorbation spectrums of the earths athmosphere. It's easy to see that the fact that we see in the visible spectrum is no accident. If the aliens have similar body-chemistry (Ie. carbon based oxygen breathers), they will face a similar absorbation spectrum. - And, due to the chemical composition of the universe this is the most likely option.

Also for radiation far away from the visual spectrum you face an issue in that organic life tends to be transparent. While it might seem convenient to be able to see through stuff, in order to actually get an image that way you need a powerfull source of EM-radiation. - If that source is present it will be fatal if it's present all the time.

  • $\begingroup$ there's a nice gap at about 10uM. Could that be useful? As-for the radio waves, could some macroscopic organ (a literal antenna) be shaped just the right way to interact with them in any non-negligible way? $\endgroup$ – John Dvorak Jul 13 '15 at 10:45
  • $\begingroup$ Another problem with "organic life tends to be transparent" is that the detection organs need to contain something opaque to the wavelength so that the photons can be absorbed. That is the only way that detection occurs. $\endgroup$ – Neil Slater Jul 13 '15 at 10:54
  • $\begingroup$ @JanDvorak 10uM could maybe be useful if you have a large cool sun. Radio waves not so much, even if there is enough radiation to be interesting, what is it that you are looking at? Most organic molecules will be essentially transparent. $\endgroup$ – Taemyr Jul 13 '15 at 11:00
  • $\begingroup$ @NeilSlater Yes, but one could imagine a creature that consumes a small amount of some metal to form part of the sensory organ. This might be a stretch, but to show lack of feasibility it's easier to focus on the lack of utility even if you get past the challenges in forming the organ in the first place. $\endgroup$ – Taemyr Jul 13 '15 at 11:02
  • $\begingroup$ Any strip of conductive material of the appropriate length should be able to interact with radio waves. Could I be looking for other creatures' bloodstreams this way? Or, alternatively, does my sun flare in the radio wave frequency before sending deadly material my way? If so, it would be nice to detect an electric current being produced in whatever body of fluid my body happens to have lying around. $\endgroup$ – John Dvorak Jul 13 '15 at 11:12

Aliens? Some dull, old Terran fish can see ultraviolet:


As for factors, absorption of light in deep water differs between wavelengths.

  • $\begingroup$ Yes. Different species on Earth right now see in different wavelengths. Some are very close to us in what they can perceive. Others, as user10915 points out, see outside our range. Have a look at the perception available to snakes. They have an organ that can 'see' infra red. If I remember correctly, mosquitos can do the same but I haven't checked that. $\endgroup$ – chasly from UK Jul 13 '15 at 11:30
  • $\begingroup$ Indeed, some people can see in ultraviolet - the retina is sensitive but the cornea is opaque, so if the cornea is removed, they can see the near-UV. (It's been suggested that this is one reason Monet's later paintings - after cataract surgery - were quite so distinctive.) $\endgroup$ – Andrew Jul 13 '15 at 18:16

All you need to do is evolve on Earth, Fish, Insects, Birds, Bees all have extended vision (typically into the ultraviolet), The Mantis Shrimp for example are among a number of creatures right here that have extended Ultra Violet (in the case of the shrimp with about 5 distinct bandwidths of ultraviolet) have a they ability to see in polarised light and view multispectral images. Their eyes are generally considered to be the most complex eyes in the animal kingdom.


Certainly. Dogs "see" in high detail with their noses. Bats and owls "see" with their ears. Sharks and fish have lateral lines that respond to tiny electric field changes in water and can paint a picture of their surroundings that way.

Of course the detail level of such a sense would depend heavily on the wavelength of the signals being received. You simply can't "see" something that's smaller than that.
Mind that this is a simplified picture, as distance increases you need a shorter wavelength to see something (which is why you can't see a grain of sand on the moon using even the strongest, most perfect optical telescope from earth orbit).

So to get a similar or higher level of detail you'd need to go into the ultraviolet or shorter.


No, they could not

Small variations are surely possible but large variations are highly unlikely and you seem to be interested in the latter.

Visible light and the region around it behaves differently from longer and shorter wavelengths. Visible light is in the region of electromagnetic wavelengths that interact with the bond structure of individual molecules. This is required not just for the radiation to be detected by the organism through the obvious means of interaction with chemically based life but also for it to carry useful information about the environment around the organism. Thus it is both unlikely that it could evolve and unlikely that it could be meaningfully used to 'see'.

Have a look at the properties sections of Wikipedia article on electromagnetic radiation for more about why this is so.

  • $\begingroup$ That part about detection by chemically based life is one of the things I had in mind when I asked this question. I guess it's no coincidence that the wavelengths of visible light are similar in scale to the sizes of atoms and molecules. $\endgroup$ – ItsTimmy Jul 13 '15 at 18:27
  • $\begingroup$ What you say is technically true, but the useful range is far broader than you imply. At the longwave end, pit vipers can see thermal infrared; at the shortwave end, the mantis shrimp can see deep ultraviolet. It's really only radio and X-rays that aren't used by something on Earth. $\endgroup$ – Mark Jul 13 '15 at 23:18
  • $\begingroup$ From the question: "There are known organisms on Earth than can see in near-infrared or near-ultraviolet, but that's not I'm asking about". The kind of thing you're talking about is the kind of small variation I accept is possible but not the kind of very different perception I think the question is asking about. $\endgroup$ – Jack Aidley Jul 14 '15 at 17:07


I think your definition of seeing is a bit skewed - for a life form the most important part is not what level of acuity they have but rather that they can perceive enough to survive in their environment. Take for example cats - they have poorer acuity and color perception than humans but superior night vision which is ideal for a nocturnal predator.

For herbivores detecting motion is often much more important than detail, which is why they often have a wider field of motion but poor binocular vision.

Also the idea that a creature needs to have a sun for to be able to see is bunk. Take for example barbeled dragonfishes which emit a red glow which allows them to see their prey in complete darkness. You could also imagine creatures which generate IR or even UV to power their own "active" vision.

We also have many creatures on earth which use sonar as an augmented sense. If you imagine creatures at the scale of a blue whale it's not completely improbable that they could perceive radio waves. Imagine for example a huge gas filled organism which flies around filter-feeding spores from the atmosphere.

We also know that birds can perceive electromagnetic radiation although they don't "see" it but rather "feel" it in the form of a sense of direction.

A more interesting question is whether an alien race with completely different sensory organs could reach a technologically advanced state. What would a civilisation of blind creatures look like?


You mention IR and UV vision. UV vision in birds works through cone cells which are slightly different from human ones. IR vision in snakes uses another mechanism.

For sufficiently small values of "outside" there could be more types of cone cells. Would that go far enough for your requirements?


Humans see best in that part of the spectrum that is strongest with our sun.
That makes it very plausible that any species evolving on a planet that orbits a star with a different spectrum to see best wherre that star has its maximum.

Additionally, as @o.m. already mentionned, snakes and birds see in a different spectrum than humans do.

So, there is no reason not to believe that a different species could evolve that has eyes seeing a different or even a much wider spectrum.


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