eli5 How do we “know” how a fly sees things?

151 views

I went to an exhibit in the Tulsa Zoo that had a little area that supposedly shows how a common house fly sees the world, in a hexagonal pattern. How do we know that is how they see?

In: 1

12 Answers

Anonymous 0 Comments

That’s the shape of their compound eye lenses, and thus the image it projects onto their many retinas.

What their eyes see looks like that.

Now what does their fly brain actually do to this image in post processing?

That’s more mysterious. Your brain does a ton of image editing to flip the image and stitch your two eyes together into one field of view. Their brain is a lot smaller and presumably doesn’t have the capacity to do a ton of intense image processing, but they’re probably not just perceiving the raw image either.

What you “see” (light hitting detector cells) and what you “perceive” (the image your brain actually generates) aren’t necessarily the same. You can tell what an animal sees by dissecting their eyes. Determining what they perceive is much more difficult.

Anonymous 0 Comments

We do not know how the experience the world. What we do know is how their eyes work.

The have [https://en.wikipedia.org/wiki/Compound_eye](https://en.wikipedia.org/wiki/Compound_eye) and to quote the article

>A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia,[1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light.[2]

If you look at the lens they are not round but mostly hexagons and sometimes less-sided [https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg](https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg)

So the hexagon pattern with single colors per hexagon is a way to try to show us what they see. The low resolution is something we know their vision havs, and that is a major part of what the display tries to show. It is not perfect and has the limitation of our eye so can’t show the advantage of the compound eye.

I would expect from the point of view of a fly they do not see a large single-color block but instead, their whole vision has a lower resolution. But that is a very hard thing to illustrate to us in another way.

Anonymous 0 Comments

I’m not a fly vision expert, but I can relate this experience:

When flies are “grooming” their eyes, they aren’t paying as much attention to their surroundings, and they’re much easier to smack with a flyswatter.

Anonymous 0 Comments

We do not know how the experience the world. What we do know is how their eyes work.

The have [https://en.wikipedia.org/wiki/Compound_eye](https://en.wikipedia.org/wiki/Compound_eye) and to quote the article

>A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia,[1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light.[2]

If you look at the lens they are not round but mostly hexagons and sometimes less-sided [https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg](https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg)

So the hexagon pattern with single colors per hexagon is a way to try to show us what they see. The low resolution is something we know their vision havs, and that is a major part of what the display tries to show. It is not perfect and has the limitation of our eye so can’t show the advantage of the compound eye.

I would expect from the point of view of a fly they do not see a large single-color block but instead, their whole vision has a lower resolution. But that is a very hard thing to illustrate to us in another way.

Anonymous 0 Comments

That’s not really how it looks. We don’t know exactly what it looks like, but we can get pretty close by examining the structure. For instance you need a large aperture to get a lot of details, because you’re getting more light. But in compound eyes they don’t have very big apertures. So no part of the compound eye will get enough information from light to form a real picture.

But since there are so many, it is getting information from a huge number of points at a time. This would let you detect movement very well, but not a lot else.

We can simulate this by creating artificial lenses in the same size and shape of the eye. Its not perfect, but its close enough.

Anonymous 0 Comments

I’m not a fly vision expert, but I can relate this experience:

When flies are “grooming” their eyes, they aren’t paying as much attention to their surroundings, and they’re much easier to smack with a flyswatter.

Anonymous 0 Comments

I’m not a fly vision expert, but I can relate this experience:

When flies are “grooming” their eyes, they aren’t paying as much attention to their surroundings, and they’re much easier to smack with a flyswatter.

Anonymous 0 Comments

That’s the shape of their compound eye lenses, and thus the image it projects onto their many retinas.

What their eyes see looks like that.

Now what does their fly brain actually do to this image in post processing?

That’s more mysterious. Your brain does a ton of image editing to flip the image and stitch your two eyes together into one field of view. Their brain is a lot smaller and presumably doesn’t have the capacity to do a ton of intense image processing, but they’re probably not just perceiving the raw image either.

What you “see” (light hitting detector cells) and what you “perceive” (the image your brain actually generates) aren’t necessarily the same. You can tell what an animal sees by dissecting their eyes. Determining what they perceive is much more difficult.

Anonymous 0 Comments

That’s the shape of their compound eye lenses, and thus the image it projects onto their many retinas.

What their eyes see looks like that.

Now what does their fly brain actually do to this image in post processing?

That’s more mysterious. Your brain does a ton of image editing to flip the image and stitch your two eyes together into one field of view. Their brain is a lot smaller and presumably doesn’t have the capacity to do a ton of intense image processing, but they’re probably not just perceiving the raw image either.

What you “see” (light hitting detector cells) and what you “perceive” (the image your brain actually generates) aren’t necessarily the same. You can tell what an animal sees by dissecting their eyes. Determining what they perceive is much more difficult.

Anonymous 0 Comments

We do not know how the experience the world. What we do know is how their eyes work.

The have [https://en.wikipedia.org/wiki/Compound_eye](https://en.wikipedia.org/wiki/Compound_eye) and to quote the article

>A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia,[1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light.[2]

If you look at the lens they are not round but mostly hexagons and sometimes less-sided [https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg](https://upload.wikimedia.org/wikipedia/commons/6/64/Krilleyekils.jpg)

So the hexagon pattern with single colors per hexagon is a way to try to show us what they see. The low resolution is something we know their vision havs, and that is a major part of what the display tries to show. It is not perfect and has the limitation of our eye so can’t show the advantage of the compound eye.

I would expect from the point of view of a fly they do not see a large single-color block but instead, their whole vision has a lower resolution. But that is a very hard thing to illustrate to us in another way.