How do we know what colors animals see? Are any creatures able to see more colors?

Factual Questions
1

I guess we all know bulls don’t really see red as a color, and flys don’t think a yellow bulb is lit.

And I’ve often heard most animals are colorblind.

But I wonder. Bears seem to have no trouble picking out the red berries at the zoo that would be well hidden to my red-green colorblind friend.

Obviously apes must have color vision, since they never wear plaid.

But can’t we tell exactly what they see by looking at the chemicals in their retinas? Just see which dyes react to different colors.

Since humans have 3 reacting dyes they see the rainbow.
My friend as only 2 dyes and sees a much simplified rainbow.

But what if an animal (a bat or a fish or a dragonfly) had different dyes entirely? Ones that react to ultraviolet or infrared. Would we have bothered to test for this?

We always seem to think of animals as inferior to us, but we know some birds have sharper vision. Might animals also see more colors?

2

I think Cecil touched on this topic in More of the Straight Dope. The colors an animal sees are ascertained by its ability to tell a foodless tray, or card, or whatever, from one with food, by association of one color, or no color, with an empty tray or whatever, and another color with a tray containing food. Admittedly with cats and dogs this takes a very long time, as Cecil noted; but eventually they determined that cats and dogs can see color–it’s just not very important to them.

3

Try to imagine a color you havn’t seen before, like a color in the Infrared spectrum, or like your colorblind friend trying to imagine when green is like. It boggles the mind.

4

Many animals are dichromats, as are people who have red-green colorblindness. They can distinguish some colors that trichromats can, but not all.

It has been determined that cats can see into the infrared, and that bees can see into the ultraviolet.

Cecil’s column is Are cats and dogs really color-blind? How do they know?

A related thread can be seen here: Colorblind animals

5

The human retina is actually sensitive to ultraviolet as well, but the lenses of our eyes are opaque to it. So, we could see ultraviolet with the proper modifications. I wonder how an adult brain would process it. I have little doubt that a person growing up able to see UV would find it completely natural.

6

That sounds like great news.
When we get cataracts we can specify artificial lenses that are UV-transparent and see more things.

?? Guess they would probably just translate into the normal colors, since only the normal neurons would be activated.
Sort of like night-vision goggles that change the extra wavelengths to green. Only in this case, probably purple.

So you could read in a black-light filled room, which would look bright purple and white to you. Others could only see your bleached shirt and blackness.

7

a friend’s grandad had cataract surgery and had his lenses removed. what with his already bad vision, he wore thick glasses for most of his life. but a few years back he gt contacts, and was stunned to find he could see into the ultraviolet range.

I believe he could see the patterns on flowers and all, but they were purplish or bluish.

8

I was always told animals are colourblind.
I was also told bright colours in nature either attract things (like birds to flowers) or scare them off, as in I’m bright red, I’m poisonous.
I decided not to believe everything I was told, so I tried an experiment on my poor unsuspecting dog. I took her to a park with a couple of oranges and lemons, walked about 20 metres away from her and threw them like they were balls. After catching the first lemon, she avoided anything I threw that was yellow. Orange didn’t bother her. However, when I felt guilty and got her tennis ball out, she avoided that at first.
My conclusion is that my dog, and probably cats too, can distinguish different colours.
Um, I should probably also mention that my dog catches everything on the full and tends to bite hard, so when she caught the oranges and lemons, she got the juice in her mouth straight away.

9

Many fish have excellent color vision.

10

Ever look directly AT a black light? It’s violet, but there’s just something odd about the colour… Like it sticks out of something. Can anyone else see this?

11

Near-ultraviolet is possible - many flowers are very bright in UV, and many insects use this to find flowers. Far UV would be difficult to detect since water absorbs a lot of it, and it’s hard to imagine a completely dry eyeball evolving naturally.

Infrared - especially far infrared - would be problematic for warm-blooded animals because the eyeball itself emits a lot of far infrared. All you would see is a constant bright glow. It’s less of a problem with cold-blooded animals, and certain snakes do detect infrared, not with their normal eyes but with a separate organ. Of cousre, one could imagine a mammal with eyes on stalks to cool them down and detect infrared - it would be a big advantage to be able to detect the body heat of prey in complete darkness. Even easier for aquatic mammals (water-cooled eyes!), though I’m not sure how useful IR is in the water.

I have no idea if there are animals out there with more than 3 types of cones. I’m glad we only see 3 colors though - imagine how expensive TVs and color film would be if they had to reproduce, say, 5 colors.

12

I’ve got a printer that can use six “primary” (not really, but you know what I mean) ink colours. So that’s probably not that big a deal. But yes, CRTs and other displays would be more complex.

I’ve been wondering about this ever since I read in one of Arthur C Clarke’s (I think) books that the Brits had discovered that the human eye was sensitive to UV back during the World Wars. And yes, it was cataract sufferers with new UV-transparent glass lenses that clued them in.

So what did they do? Gave the ex-cataract-sufferers UV-only flashlights and got them to send and receive coded spy messages on the shores of Nazi Europe…

I keep wondering what would UV look like… purple, but more so I presume. Presumably it is something that is literally indescribable to anyone who can’t see it.

I read also that the reason our normal lenses do not pass UV is that they can’t focus red and UV to the same point, and everything would appear colour-fringed: in other words the chromatic aberration would be hell. The same effect occurs through very thick glasses. Do these UV-seeing people experience that?

Perhaps related to this is the fact that the range of normal vision is just under one “octave”, or doubling of frequency. Does the range of viewed UV frequencies reach that doubling? Are there strange visual effects when it does?

And what happens to the viewed colour balance of artwork, painted surfaces, TV sets, computer displays, and so on, for viewers who have a greater visual colour range than the designers anticipated? I could just see a UV-viewer raising hell in art class…

I almost want to have a UV-transparent lens put in… in ONE eye.

13

No, I think it will look perfectly ordinary. If you put in a UV-transparent lens, one or more types of rods (red, green and/or blue) and probably the cones would react to UV. Which means that UV would appear as red, green, blue, or a combination of those colors. If they excited the cones but not the rods, maybe that would feel different and strange, but I think that’s unlikely. If UV just escited the rods, it would appear white (gray).

Wouldn’t the UV damage the retina though? Would you really want UV-transparent lens?

14

I can… looks fuzzy too, but I see similar things when I look at any blue lights when it’s dark out, or the sun shining through a blue stained-glass window. I’ve always wondered if that’s normal or if I’m just unable to focus higher frequency light very well (blue and violet are higher, right?).

15

First, I was under the impression that glass was UV-opaque, which was the reason why sunlamp tubes are made of quartz rather than glass. Second, if the lenses in our eyes are UV-opague, why are concerned about sunglasses having UV protection?

16

To answer Frogstein’s question, I believe the corneas (lenses) themselves can be damaged by UV light, so dark glasses help protect against developing cataracts, which is the fogging of the cornea.

I just got back from my father’s first check-up after getting a new cornea in his left eye, because of cataract surgery. At my request he asked the doctor if he would be able to see UV, but she said that the replacement lenses that are put in nowadays are opaque to UV light.

17

Sit back, get comfortable, enjoy:

Colour scanning in the mantis shrimp Odontodactylus

[snip]
Their eyes are basically compound eyes of the ordinary apposition type, which provide an erect two-dimensional image. However, stretching more or less horizontally across each eye is a band of enlarged facets, six rows wide. This mid-band, which has a field of view only a few degrees in width, contains the animals’ extraordinary colour vision system.

This consists of four of the mid-band rows (the other two subserve polarization vision; and in each row the receptors are in three tiers. Each of these 12 tiers contains a different visual pigment, giving the animal the potential for dodeca-chromatic colour vision, with eight pigments covering the visible spectrum, and a further four in the ultraviolet (Marshall et al. 1999).
[ital original; reformatted and some references omitted]

From the all-around extraordinary Animal Eyes, Michael F. Land (NY:Oxford University Press, 2002).

FWIW, these same shrimp buggers wham-bam their pincers with such force they produce an underwater optical shock:

…[their] weapons are employed with blinding quickness, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 m/s from a standing start.[10] Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as cavitation bubbles.[10] The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow.[11] Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill.

The impact can also produce sonoluminescence from the collapsing bubble. [wiki]

ETA: just saw this blurb in Nature from 2014 “debunking” super duper color vision, according to title …havent read it.

18

Cataracts are in the lens, not the cornea. I’ve had the surgery. In my case, the surgery itself caused some misery in the cornea that took a long time to approach normal, so maybe your dad’s cornea was replaced for a similar problem. Or one of you is confused about what was replaced and why.

UV light can damage the retina and lead to macular degeneration.

19

Getting a bit off topic but I’ve noticed focus problems with blue light too, especially the bright blue LED Christmas lights. Also I can’t focus on red and blue objects together, like alternating color text.

20

Note that this is a 17 year old thread.

Anyway, there is some evidence that a minority of women are tetrachromats, with 4 color vision instead of three.