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  • Jumping spiders have great eyes

  • four pairs of them, each pair with a different task.

  • The result is fantastic vision that allows them

  • to stalk and hunt prey, and make some spectacular jumps.

  • But how exactly do those eyes work?

  • Scientists know they interact with each other,

  • but in what way?

  • To give a spider an eye test, researchers

  • had to attach the creature to the apparatus.

  • They held it down with a plastic and paraffin film

  • and made an opening to dab some wax on the spider head.

  • Then, they attached a hat straight out of Dr. Seuss,

  • and put the spider in a custom-built eye tracker

  • one of only two such machines in the world.

  • Held in place on a trackball, the spider

  • watched video images.

  • Ultraviolet light penetrated the spider's head

  • to illuminate what was going on in there,

  • and researchers aimed a camera at the spider's

  • two main eyesthe big ones up front.

  • Flexible tubes from the eye to the retina

  • allow the spider to look here and there.

  • See them moving?

  • Here, the image that the spider is seeing

  • is superimposed over the retinas.

  • They look like boomerangs.

  • You can see them following the black dot across the screen.

  • But the retinas have a small field of vision.

  • They mainly pick up fine detail,

  • so they have to know where to look.

  • That's the role of the most forward pair of small eyes.

  • They pick up motion and alert the main eyes.

  • When the small eyes were painted over,

  • the main eyes were in the dark, like in this example.

  • See, the retinas don't track the dot.

  • Figuring out how the spider's tiny brain

  • manages this eye-to-eye communication

  • is next on the agenda.

  • And in case you were wondering,

  • the spiders are freed at the end of the experiment.

  • Off comes the hat, off goes the spider.

Jumping spiders have great eyes

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