this is one sound you don't want to hear.

這是一個你不想聽到的聲音。

The warning of a rattlesnake.

響尾蛇的警告。

Now, just because a rattlesnake's tail

就因為響尾蛇的尾巴...

sounds like a built-in maraca

聽起來像一個內置的馬拉卡

doesn't mean it works like one.

並不意味著它的工作方式像一個。

There are no beads rattling about in here.

這裡沒有珠子的響動。

So, what's really going on inside?

那麼，裡面到底發生了什麼？

If you opened up a rattlesnake's rattle and shook it,

如果你打開響尾蛇的撥浪鼓，然後搖動它。

absolutely nothing would fall out.

絕對不會掉出來。

After all...

畢竟...

Tim Colston: So, rattlesnake rattles are hollow.

蒂姆-科爾斯頓所以，響尾蛇的響聲是空心的。

Narrator: That's herpetologist Tim Colston.

旁白：那是爬行動物學家Tim Colston.

He says the secret to that rattling sound

他說這聲音的祕密是什麼？

comes from the shell itself.

來自於外殼本身。

It's made of keratin,

它是由角蛋白製成的。

the same hard substance as your fingernails.

和指甲一樣的硬物。

The keratin is arranged in a chain of interlocking rings,

角蛋白以連鎖的方式排列，環環相扣。

which are hooked together by tiny grooves along their edge.

邊緣有細小的凹槽勾在一起。

Now, watch what happens to those rings

現在，看看那些戒指會發生什麼吧

when Colston shakes the rattle.

當科爾斯頓搖動撥浪鼓時。

Colston: Whenever I shake them very fast,

科爾斯頓每當我搖晃他們非常快。

they bump together, producing the sound.

它們碰撞在一起，產生了聲音。

Narrator: Because the rattle is hollow inside,

旁白：因為撥浪鼓裡面是空的

sound waves can bounce off the walls and echo,

聲波可以從牆壁上反彈併產生回聲。

the same way shouting in a cave amplifies the sound.

就像在山洞裡大喊大叫會放大聲音一樣。

And the bigger the cave, or hollow rings in this case,

而且是越大的洞穴，也就是這裡的空心環。

the more amplification, so the louder the rattle.

擴音越大，所以響聲越大。

But a big, hollow chamber can't get the job done on its own.

但一個大而空的腔體是無法獨立完成任務的。

That's where the tail muscles come in.

這就是尾部肌肉的作用。

Rattlesnakes are equipped with three powerful shaker muscles

響尾蛇擁有三塊強大的甩尾肌肉。

at the base of their spine.

在其脊柱基部。

These can contract so fast,

這些可以收縮得這麼快。

they vibrate the rattle up to 90 times a second.

它們每秒振動響聲高達90次。

For comparison, the human eye blinks

相比之下，人眼眨動

15 to 20 times a minute.

每分鐘15到20次。

By vibrating so quickly,

通過如此快速的震動。

the rattle makes a sound that hits

滴答滴答

between these specific frequencies.

這些特定頻率之間。

And it just so happens that that range

而恰好那個範圍

is best heard by mammals.

哺乳動物最容易聽到。

It turns out, that tail is custom designed

原來，那個尾巴是定製的

to make predators like bears, raccoons,

來製造熊、浣熊等食肉動物。

and weasels listen up.

和黃鼠狼聽好了。

Unfortunately, snakelets

不幸的是，小蛇

(yes, that's what baby snakes are called),

是的，這就是小蛇的名字）。

don't have this warning signal.

沒有這個警告信號。

Colston: Whenever a rattlesnake is born,

科爾斯頓。每當響尾蛇出生。

it just has a single button.

它只是有一個單一的按鈕。

It looks similar to the one,

看起來和那個差不多。

I don't know if you can see, that's on the end here.

不知道你看不看得到，那是在這頭。

Narrator: Without a second button to clack against,

旁白：沒有第二個按鈕可以抵擋

the baby rattle can't make any noise.

嬰兒搖鈴不能發出任何聲音。

But every time they shed their skin,

但每一次他們脫皮。

they add another button to the base of the rattle,

他們在撥浪鼓的基礎上又增加了一個按鈕。

which grows into the segment above,

其中成長為上面的部分。

sort of like the structure of a Russian stacking doll.

有點像俄羅斯堆積娃娃的結構。

The rattle will keep growing until...snap!

撥浪鼓會不斷壯大，直到......啪啪啪!

Just like your fingernails,

就像你的指甲一樣

those rattles are pretty fragile,

這些搖鈴是相當脆弱的。

and they can break off if they get too long.

而且如果太長的話，它們會斷掉。

In fact, the rattles rarely make it past eight to 10 rings

事實上，響聲很少能超過8到10環

before snapping off.

才啪啪啪地離開。

Luckily, snakes shed their entire lives.

幸運的是，蛇的一生都在蛻變。

So the rattle will grow back good as new,

所以老鼠會恢復如初。

which is good news for you hikers,

這對你們徒步旅行者來說是個好消息。

because that handy tail can mean the difference

因為那條方便的尾巴可以決定一切

between an exciting day on the trail

興奮的一天之間

and a painful trip to the hospital.

並痛苦地前往醫院。