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PeteyMax t1_j93sebp wrote

Most spiders have two main eyes similar to ours, each having a lens and a retina with multiple light sensing organs for detecting images. Unlike our eyes, however, it is the retina rather than the eye that moves in order to both focus and direct the view. Since the field of view tends to be quite narrow and spiders cannot move their heads, in addition to the two main eyes, spiders also have between four and six other simple eyes scattered around their heads. These eyes can detect motion so that the spider can orient itself towards the source of interest.

Here is a video showing a translucent spider where you can see the motion of its retina:

https://www.youtube.com/watch?v=gvN_ex95IcE

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quaoarpower t1_j93xi5v wrote

“Most spiders” may be stretching things a bit because a lot of spiders do not have this kind of sophisticated arrangement

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BackWaterBill t1_j941gax wrote

Name which ones don't because the three banded South American silk weaver certainly does.

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HopesBurnBright t1_j96qzwy wrote

You really pulled a “oh you like spiders? Name every spider”

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BackWaterBill t1_j96r8s0 wrote

You'd be surprised how often that works, I got a geography buff to teach me about the entire eastern seaboard after I "Mistook" where Ontario was.

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Mjolnirsbear t1_j9481hm wrote

I like spiders, and I knew that spider eyes are basically tubes inside the head that move...

...but this here is creepy a f.

Cool, but creepy.

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