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Using the example of the mole, explain two different types of underground adaptation.
請以鼴鼠為例，解釋說明進化出的兩種不同的地下能力類型。
Listen to part of a lecture in a biology class.
請聽生物課上的部分內容。
Many animals live underground, in the soil.
很多動物都生活在地下，在土里。
Not just little animals like worms but also bigger animals like mammals.
不只是像蟲子這樣的小動物，還有像哺乳動物這樣的大一些的動物。
Living underground has its advantages. It protects animals from above ground predators.
生活在地下有其優勢，能夠保護動物不受地上捕食者的侵害。
However, the underground environment also presents challenges.
可是，地下環境同樣也存在著挑戰。
And animals that live underground have developed physical adaptations to deal with them.
所以生活在地下的動物進化出了能夠對付這些挑戰的身體能力。
One challenge is, well, simply how to move underground through the dirt.
其中一個挑戰，只不過就是如何穿過泥土在地下行動。
Another challenge for the animal is to protect vulnerable parts of its body from the environment that it's moving through.
動物們面臨的另一個挑戰就是從它們穿過的環境中保護它們脆弱的身體部位。
Now, moving through soil is not like moving through air or water,
穿過泥土和在空中或水中行動完全是兩回事，
because soil, earth, is thick and dense,
因為泥土，土壤，又厚又密，
so animals that live underground have evolved physical features that help them move through dirt efficiently.
所以生活在地下的動物們進化出了能夠幫助它們有效地穿過泥土的身體特征。
For example, the mole, a small, furry mammal, has really wide, super strong front feet with big claws.
比如鼴鼠，一種小小的，毛茸茸的哺乳動物，它長著有一對大爪子的前腳，它的前腳很寬，超級強壯。
The mole's feet act like, uh, like shuffles, so it can dig through dirt.
鼴鼠的前腳就像...像鏟子一樣，所以它可以在土里挖通道路。
The claws cut into the dirt, loosen it up, and once the dirt is loosened up,
鼴鼠在土里前進的時候，會把爪子插進土里，把土弄松，一旦土松了，
the broad feet throw the dirt behind the mole as it moves forward.
它就會用寬闊的前腳把土扔到身后。
These shuffle-like front feet allow a mole to dig its way through the dirt astonishingly quickly.
這些鏟子一樣的前腳使得鼴鼠可以很快地在土中挖出道路前進，速度快得令人震驚。
But even for an animal that can move efficiently through the dirt, living underground can still be problematic.
但是即使對那些能夠在土中迅速移動的動物來說，生活在地下也還是充滿問題的。
Because it's easy for particles to get caught in sensitive parts of the animal's body, like for mammals, in their eyes.
因為泥土顆粒很容易會掉進動物身體的敏感部位，比如對于哺乳動物來說，會掉進它們的眼睛里。
So underground animals have developed adaptations to prevent this.
所以生活在地下的動物進化出了能夠預防這種情況的能力。
Again, let's take the example of the mole.
我們再次以鼴鼠為例。
To begin with, moles have tiny eyes and these eyes are covered with a thin skin,
首先，鼴鼠們的眼睛非常小，而且眼睛上覆蓋著一層很薄的皮膚，
a protective membrane that's actually got hair on it.
這是一種實際上長著毛的保護性薄膜。
These hairs protect the moles' eyes from dirt particles.
這些毛發能夠防止泥土顆粒進入鼴鼠的眼睛。
So as the mole goes digging through the dirt with its head push forward,
所以當鼴鼠頭朝前在土里挖通道路的時候，
the dirt particles come into contact with the hairy membrane covering the mole's tiny eyes.
這些泥土顆粒接觸到的就是覆蓋著它的小眼睛的毛茸茸的薄膜。
And the particles just slide by. Don't get caught in the mole's eyes.
接著這些顆粒就會順勢滑落，不會掉進鼴鼠的眼睛里。
So the eyes, the mole's sensitive parts, are protected.
于是鼴鼠的眼睛，它的敏感部位，就得到了保護。
