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

牠們有四對眼睛，每一對都有不同功用

The result is fantastic vision that allows them

這些功用使牠們擁有絕佳視力，得以

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

追蹤、獵殺獵物，還有跳得老遠

But how exactly do those eyes work?

那這些眼睛是如何作用的？

Scientists know they interact with each other,

科學家知道每對眼睛之間會交互作用

but in what way?

但不知道是在哪方面

To give a spider an eye test, researchers

為了給蜘蛛視力測驗，研究人員

had to attach the creature to the apparatus.

必須把裝置裝在蜘蛛身上

They held it down with a plastic and paraffin film

再將牠壓在塑膠和石蠟做成的薄膜下

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

並開一個缺口，在蜘蛛頭上塗上少量的蠟

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

接著，他們幫蜘蛛戴上像蘇斯博士故事裡的帽子 (出自其作品：魔法靈貓)

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

之後，將蜘蛛放入一個量身打造的眼睛追蹤器中

one of only two such machines in the world.

此追蹤器全世界僅有兩台

Held in place on a trackball, the spider

最後，將蜘蛛安置在追蹤球上，讓牠

watched video images.

觀看影片圖像

Ultraviolet light penetrated the spider's head

紫外線會穿入蜘蛛腦內

to illuminate what was going on in there,

照亮蜘蛛的腦中活動

and researchers aimed a camera at the spider's

研究人員將一台攝影機架在蜘蛛

two main eyes — the big ones up front.

主要的眼睛上 — 也就是頭部前方最大的那一對

Flexible tubes from the eye to the retina

眼睛到視網膜中靈活彎曲的軟管

allow the spider to look here and there.

讓蜘蛛可以四處張望

See them moving?

有看到眼睛在動嗎？

Here, the image that the spider is seeing

看這裡，蜘蛛看到的景象

is superimposed over the retinas.

在視網膜上呈現疊映狀態

They look like boomerangs.

看起來就像迴力鏢

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

可以看得出來牠們目光會跟隨螢幕上的黑點

But the retinas have a small field of vision.

但視網膜的視力範圍很小

They mainly pick up fine detail,

以至於牠們主要是看最細節部分

so they have to know where to look.

所以，牠們必須知道，哪些該看、哪些不該看

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

這時，頭部最前方的小眼睛就派上用場了

They pick up motion and alert the main eyes.

牠們捕捉影像的移動，並警惕主要的那對大眼睛

When the small eyes were painted over,

當那對小眼睛被塗上顏料

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

主要的大眼睛只會看到一片漆黑，像你眼前所見

See, the retinas don't track the dot.

看到了吧，視網膜不會跟著黑點移動

Figuring out how the spider's tiny brain

挖掘蜘蛛小小的腦袋裡

manages this eye-to-eye communication

到底是如何處理這種眼對眼的溝通方式

is next on the agenda.

是下一個待研究事項

And in case you were wondering,

另外，如果你好奇的話

the spiders are freed at the end of the experiment.

這些蜘蛛在實驗後都被釋放囉！

Off comes the hat, off goes the spider.

一旦脫下帽子，蜘蛛就自由了！