In fact, it is their rib cage, and their spine, and their vertebrae, and their sternum.

事實上，這就是牠們的肋骨、牠們的脊椎、牠們的胸骨。

Basically, a turtle's skeleton is inside out.

基本上，烏龜的骨架是由內而外的。

And just like you can't take a skeleton out of a person, right, you can't take a turtle out of its shell either.

就像人不能沒有骨架一樣，烏龜也不能沒有骨架。

But if you could, you'd probably be surprised by what you'd discover.

但如果你有辦法抽出它的骨架，你可能會很驚訝你將發現的東西。

Here's the inside of a turtle.

這是一隻烏龜的內部。

That's Maria Wojakowski, a biologist who's been studying turtle ecology for more than a decade.

這位是 Maria Wojakowski，一位研究烏龜生態學已有十多年的生物學家。

Here's your shoulder girdle.

肩帶在這裡。

Here's your hip girdle.

骨盆帶在這裡。

Notice how those hips and shoulders are actually inside the turtle's rib cage?

你有注意到那些臀部和肩膀實際上是在烏龜的肋骨裡嗎？

Turtles are one of the only land animals on the planet with this feature.

烏龜是地球上唯一有這個特色的陸地動物之一。

They're also some of the only animals that can breathe with their butts.

它們也是唯一能用屁股呼吸的動物之一。

You see, inside a turtle shell is a very particular respiratory system.

烏龜殼裡有一個非常特殊的呼吸系統。

You will see the lungs towards the top here.

你會看到這裡的肺部朝上。

Now, most land animals breathe by expanding and contracting their ribs, which creates a natural pump that guides air in and out of their lungs.

大多數陸地動物呼吸都是通過擴張和收縮他們的肋骨來形成一個自然泵，引導空氣在牠們的肺部進進出出。

But turtles can't do this because their rigid shells don't expand.

但烏龜不能這樣做，因為它們的硬殼不會膨脹。

So instead they rely on sheets of muscles within their shell to pump in oxygen through their mouths.

因此他們取而代之的是依靠龜殼內的肌肉來透過嘴巴吸入氧氣。

That is, most of the time.

大部分的時間是這樣呼吸啦。

Then there are other times when turtles breathe out the other end, more specifically, through what scientists call the cloaca.

有時候烏龜會用另一頭呼吸，更具體地說，是透過科學家稱作泄殖腔的地方呼吸。

It's the same opening that turtles use to urinate, defecate, and lay eggs.

這和烏龜排尿、排便，以及產卵的地方是一樣的。

And in some cases, it can double as a set of gills, sucking in water and absorbing the oxygen within.

而在某些情況下，它可以作為一組腮幫子吸水並吸收其中的氧氣。

Scientists think that turtles do this when they're spending long periods of time underwater, like when they're hibernating.

科學家認為，烏龜在水下長時間停留時就會這樣做，例如在冬眠時。

And if you look really closely at the inside of a shell, you'd discover another feature that helps with hibernating underwater: a scaffold-like structure that can store and release chemicals.

而且，如果你仔細觀察龜殼的內部，會發現另一個有助於水下冬眠的特色：可以存儲和釋放化學物質，類似支架的結構。

That structure actually helps turtles breathe without any oxygen at all.

這種結構其實是幫助烏龜在沒有任何氧氣的情況下還能呼吸。

It works like this:

它的原理是這樣：

Many turtles hibernate in frozen ponds that are starved of oxygen, and to survive, their metabolism switches over from aerobic to anaerobic.

許多烏龜在缺氧的冰凍池塘中冬眠，為了生存，它們的新陳代謝從有氧轉變為無氧。

That means they stop using oxygen for energy and start using glucose instead, via a process called anaerobic respiration.

這意味著他們通過稱為無氧呼吸的過程停止使用氧氣作為能量，而開始使用葡萄糖。

And the byproduct of that is lactic acid.

而這副產物就是乳酸。

Now, theoretically, this acid could build up in a turtle's body and kill it.

理論上，這種酸在烏龜的身體內累積會殺死它。

That's where the shell's structure comes in.

這時候就是龜殼派上用場的時候了。

It can absorb the lactic acid as well as release a bicarbonate to neutralize that acid.

它可以吸收乳酸以及釋放碳酸氫鹽來中和乳酸。

It's essentially Tums, but for turtles.

這本質上是就是 Tums (中和胃酸鈣片的品牌名稱)，但是給烏龜用的。

So as it turns out, having a shell is pretty handy for certain situations.

所以事實證明，在某些情況下有一個殼是很方便的。

In fact, scientists think that turtles originally got their shells for digging, likely more than 200 million years ago.

實際上，科學家認為，龜殼最初的演化是用來挖掘的，可能回朔到兩億多年前。

They dig, like, really, really complex burrowing structures underground.

牠們在地下挖出非常複雜的洞穴結構。

And of course, shells are incredibly useful for defense against predators, no matter how fierce they may be.

當然，無論天敵有多兇猛，龜殼對於防禦天敵也是非常有用的。

Turtles are amazing.

烏龜真的奇妙。