are super old, super cool, and they deserve your respect.

非常古老也非常酷，牠們值得你的尊重

They may have already saved your life.

牠們也許曾救過你一命

First of all, they aren’t crabs. They’re members of their very own family of arthropods

首先，牠們並非螃蟹。牠們是節肢動物門底下獨特的一科

-- arthropods include insects, arachnids, and crustaceans -- known as Limulidae,

節肢動物成員包括昆蟲綱、蛛型鋼以及甲殼亞門，而鱟屬於節肢動物門底下的鱟科

and there are only four species of them in the world.

世界上屬於鱟科的僅有四個種

They’re more closely related to arachnids, like spiders and scorpions, than anything else,

相較於其他生物，牠們與蛛型鋼的關係較近，像是蜘蛛和蠍子

but really, they’re their own deal.

但說真的，牠們是獨特的

They’re also mega-ancient. The oldest horseshoe-crab fossil we’ve found is around 450 MILLION years old!

牠們非常古老，現今已發現最早的鱟化石大約距今四億五千萬年!

That means they have survived, virtually unchanged, for nearly half a billion years,

這表示牠們生存至今，幾乎沒什麼改變，長達五億年

outliving pretty much everything else.

活得比許多物種都要來得長

These guys are survivors.

他們是生存者

So what makes them so tough? Well, part of it has to do with their amazing blood.

是什麼讓他們命這麼硬呢? 有一部分關係源自於牠們神奇的血液

For one thing, it’s blue. Baby blue. Our blood is red because the substance it uses

首先，牠們的血是藍色的，粉藍色。我們的血液呈現紅色是因為負責運送氧氣的

to ferry oxygen around, called hemoglobin, contains iron. But horseshoe crabs use hemocyanin,

血紅素其中含有鐵。但鱟卻是使用血青素(血藍蛋白)

which is copper-based. So, just like iron turns red when it oxidizes, when copper meets oxygen,

血青素中含有銅。因此就如同鐵氧化會呈現紅色，當銅碰上氧氣

it turns blue.

就會呈現藍色

But that’s not even half of what makes horseshoe crab blood so cool.

但這些甚至還不到鱟的血液之所以酷的地方的一半

So sea water is chock full of bacteria, and unlike mammals, horseshoe crabs don’t really

海水是一個充滿細菌的環境，不像哺乳類，鱟並不具有

have an immune system -- no infection-fighting white blood cells at all. So if they get,

免疫系統，牠們沒有半點白血球。所以如果

say, a crack in their shell, all that bacteria just gets into their bodies and could wreak

某天牠們殼上裂了條縫，那麼各種細菌就能直接進入牠們的血液中

all kinds of havoc.

造成災難性的後果

But what they do have is a glorious chemical -- found only in their blood cells -- that

但牠們擁有驚人而獨特的化學物質(目前只在牠們的血球中發現過)

binds to and inactivates unwanted bacteria, viruses, and fungi.

可以與不請自來的細菌、病毒和黴菌結合並抑制它們作用

When the blood cells sense bad-guy invaders, they release a protein called coagulogen that

當血球偵測到不速之客時，它們會釋放出一種稱為凝固蛋白原(尚無定譯)的蛋白質

forms a gooey barrier around the infecting agents, preventing their spread.

凝固蛋白原會在感染源附近形成一層黏稠的壁壘，防止它們擴散

That clot of gooieness also essentially creates a physical barrier, sealing up the wound and

這團黏稠物質製造了一到物理屏障，封住傷口並且

preventing further infection. It’s an amazing internal defense mechanism.

避免再次遭受感染。這真是個驚人的內部防禦機制

Humans: we have no such ability. So for the past 50 years, we’ve been stealing it from

人類:我們可沒有這樣的能力。因此在過去50年之間，我們一直在

the horseshoe crabs.

從鱟的身上偷取這樣的能力

Ever since American physician Fredrick Bang discovered the weird power of horseshoe crab

自從美國外科醫師Fredrick Bang於1960年發現鱟血的非凡能力之後

blood in the 1960s, these ancient sea creatures have played an essential, yet largely-unknown,

這古老的海洋生物就一直扮演著不可或缺但也不為人知的角色

role in human medical treatment.

於人類醫療行為之中

If you have ever received any kind of drug or vaccine injection, it’s because these crabs

如果你曾經接受過任何種類的藥物或者疫苗注射，都必須歸功於鱟

made sure that injection was bacteria-free.

才能確保該次注射完全無菌

The whole thing starts when horseshoe crabs are collected from the wild, transported to

整件事情始於一隻鱟於野外中被捕獲並運送到

one of only five production labs in the world, and then rigged up for a blood drive.

世界上只有五間的實驗室，然後被迫成為血液供應源

Needles are inserted around the heart, and up to 30 percent of the animal’s blood is removed.

針頭被放置在心臟附近，接著30%的鱟血被抽出

This stuff is liquid gold, and can go for $15,000 a liter.

這玩意簡直是液態的黃金，一升要價15000美金

From there, scientists extract the coagulogen from the blood cells, and use it to test solutions

自此以後，科學家們由鱟的血球中取出凝固蛋白原，並用凝固蛋白原作為試劑

that are used in injectable drugs and vaccines.

用來檢測注射用藥物和疫苗是否無菌

If the crab-blood extract finds unwanted bacteria in the solution, it immobilizes it in a gooey clot.

如果鱟血試劑在溶液中碰上了不請自來的細菌，它會將細菌包圍在黏稠的團塊中

So if your sample doesn’t form any clots, you know that it’s bacteria-free

因此如果你在溶液中沒有發現任何團塊，那就能得知該溶液是無菌的

and safe for human use.

可供人使用無虞

This simple procedure, called the LAL, or Limulus amebocyte lysate test, is nearly instantaneous,

這簡單的檢測過程稱為LAL或者鱟血檢測，該檢測能及時看到結果

and no other test works as well.

沒有比這更好用的了

As for the crabs themselves, most seem to bounce back several days after being released

至於鱟本身，大部分的鱟都能順利恢復，在他們被放生

back into the wild, but some folks are concerned that the blood-letting weakens them more than we think.

回到野外後。但有部分人認為抽血對牠們的影響高乎我們原本預期

So LAL manufacturers tend to only collect blood once a year, to ensure they’re not

因此LAL製造流程規範一年之中只能進行一次抽血，確保人們不會

double-dipping on the same crabs, and research is being done to come up with a synthetic

剝削同一隻鱟兩次。同時用其他合成物質替代鱟血的研究正在進行當中

alternative so that we can eventually leave them alone.

因此這些生物總有一天能逃離我們的魔掌

Until then, next time you get a shot, give thanks to all those old horseshoe crabs who

下次你去打針時，記得要感謝這些古老的鱟，牠們

made your good health -- and your sore arm -- possible.

為你的健康奉獻了一份心力(也害你被打針的手臂腫痛)

Thanks for watching this SciShow Dose -- especially our Subbable subscribers. To learn how YOU

感謝收看這集SciShow Dose，特別是訂閱 Subbable的人。希望能跟我們

can help us keep sharing wonderful science like this, just go to Subbable.com. And don’t

一起傳遞這些超棒的科學訊息嗎? 那就快到Subbable.com. 最後

forget to go to YouTube.com/scishow and subscribe!

別忘了到YouTube.com/scishow 訂閱我們的頻道哦!