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What's the difference between a hard-shelled blue crab anda soft-shelled blue crab?
你知道軟殼青蟹和硬殼青蟹有什么區別嗎？
Is this a trick question?
這個問題很難嗎？
I'll give you a hent.
我來給你個提示。
It has to do with the crab's skeletal system.
這與螃蟹的骨骼系統是緊密相關的。
Skeletal system? You got me there, I know that like other crustaceans, periodicallymolt.
骨骼系統？哦，我大概懂了。就像是其它的甲殼類動物一樣，螃蟹會定期的褪殼。
That is, the crab sheds it shard shell and forms a new one.
也就是說，螃蟹褪掉原有的硬殼再重新長出新殼。
But I don't have a clue as to what that means about the skeletalsystem?
但問題是，我想不明白這怎么就和骨骼系統扯上了關系。
Well, I'll tell you.
那就由我來告訴你吧。
When a blue crab sheds its hard shell, its exoskeleton, it has to wait about aweek for the new shell to harden.
當一只青蟹褪掉了它的硬殼（也就是它的外骨骼）之后，新長出的殼要等上大概一個星期才能變硬。
Before that happens, this outer layer of tissue is too soft andflexible to transmit muscle contractions as it did, and will do again when the crab's new shell hardens.
在殼變硬之前，外面的那層“殼”太軟太韌了，以致于無法進行正常的肌肉收縮。
And yet these creatures are somehow still able to move about, even immediately after molting.
在新殼變硬之時還要再進行一次。而且，不知為何，青蟹在這種情況下還是能到處爬來爬去的，即使是剛剛褪殼的時候也是如此。
How is that possible?
這怎么可能呢？
It's possible using a hydrostatic skeleton.
使用鈴靜力骨架就可以了！
Many animals, such as worms, rely on hydrostaticskeletons all their lives.
許多種動物，比如說蠕蟲，它們一生都是靠鈴靜力骨架支撐下來的。
What this means is that muscle contractions are transmitted through anincompressible fluid.
這也就是說，肌肉的收縮通過不可壓縮鈴被傳送到了身體各部分。
Immediately after molting, the hydrostatic pressure inside crabs jumpssignificantly higher, allowing the crabs to use this pressure to move their muscles.
青蟹剛剛褪殼的時候，體內的鈴靜壓力陡然飚到很高，這使得青蟹可以利用壓力來使肌肉活動。
While ahydrostatic skeleton isn't so remarkable in itself, what is remarkable is that the crab alternatesbetween using the two kinds of skeletons.
青蟹的鈴靜力骨架并不是特別出眾，真正出眾的是青蟹在外骨骼和鈴靜力骨架之間出眾的交替使用能力。
Scientists suspect that crabs probably aren't alone inthis feat and plan to investigate the skeletal systems of other creatures that molt.
科學家們猜測，蟹并不是唯一一種此類動物，接下來，科學家們將會研究更多褪殼生物的骨骼系統。
