字神帝國英語天地

今日主題：Sharks Head Straight Home by Smell  鯊魚靠著嗅覺回家

洪欣老師推薦：托福聽力最好的課外教材：60-Second Science
康康精選托福會考的主題，堅持每天精聽一定會進步的哦!!

建議方法：
1. 先聽兩三遍 (不看文稿)
2. 再一句一句聽寫 (每句都要聽寫數遍，直到寫出85%以上的字)
3. 最後check文稿，看哪聽不出來，單字沒背過，還是發音不熟。
4. 堅持天天聽，就能每天進步哦。

MP3音檔 (按右鍵可下載聽)：喜歡的同學，幫忙推或按讚哦~~
http://online1.tingclass.net/voaspe/…/20160303sa_science.mp3

只有音檔怎夠，聽不懂地方，不用怕，康康幫你準備好中英文稿了：

中英文稿：
Some sea creatures can find their way through thousands of miles of seemingly featureless oceans. Even more impressive is the route that they take.
一些海洋生物能夠在茫茫的大海中找到方向，而最讓人印象深刻的是它們的航線。

“Well, we've known for a long time that sharks are capable of long-distance migrations, and in some cases those migrations occur along very straight paths.” Scripps Institution of Oceanography biologist Andy Nosal. “And this has always begged the question : how exactly do they know where they're going?...So, there have been a lot of hypotheses floated over the last several decades, including the idea that these sharks are using, for example, geomagnetic cues, chemical cues and others . But none of these have really been systematically tested in the field.”
“很久以前我們就知道，鯊魚能夠長途遷移，並且在某些情況下，它們的的遷徙路線是直的。” 斯克瑞普思研究生海洋生物學家安迪•諾薩爾說到。“一直以來人們都未探討問題的實質：鯊魚究竟是怎樣知道自己的去向呢?因此，過去幾十年來，人們有無數的 假設，例如鯊魚在利用地磁信號、化學信號等等。但是，所有這些假設都尚未得到系統地檢測。”

Nosal and his team suspected that the navigational secret of some sharks might be their sense of smell. They use their keen noses to find food, of course. And other fish, like salmon, are known to use olfaction to navigate.
諾薩爾和他的團隊猜測，鯊魚的導航秘訣可能是嗅覺。鯊魚可以使用自己靈敏的鼻子來尋找食物。人們知道鮭魚等其他魚類利用嗅覺進行導航。

To see if his hunch was right, Nosal scooped up some adult female leopard sharks in their preferred environment, waist-deep water off the San Diego coast. He attached a small radio transmitter behind their dorsal fins. And he half of the sharks by shoving cotton balls soaked with petroleum jelly blocked the sense of smell in their nostrils.
為了驗證猜測是否正確，諾薩爾在聖地亞哥海岸齊腰深的海水處，圈養觀察一些成年雌性豹鯊。這裡的環境為這些豹鯊所喜愛。諾薩爾在豹鯊的背鰭出裝上小型的無線電發射器。並利用佔有凡士林的棉花堵塞了一半鯊魚的鼻孔，通過這種方法來阻塞鯊魚的嗅覺。

Nosal and his crew dropped the sharks about six miles away at a spot in the open ocean. The researchers then tracked the sharks as they tried to swim back home. Four hours later, the sharks that could smell were two-thirds of the way back home—and had swum in very straight paths. But the ones with stuffed noses took erratic routes and only made it about half as far.
諾薩爾和同事們將這些鯊魚放到六公里外的開放海域中。研究人員對這些鯊魚進行跟踪記錄，因為這些鯊魚試圖游回家。四小時後，嗅覺正常的鯊魚距離家園只有1/3的路程，並且，它們游的路徑是直的。但是，鼻子被堵塞的鯊魚行程不穩，只游了約一半的距離。

Nosal thinks they all eventually got back home. “And we know that because even though their movements, even though they didn't get as close to shore and even though their paths were more wind-y, their movements were still biased towards shore. On average they still finished closer to shore than when they started.” And those jelly-soaked cotton balls eventually disintegrate, returning the sharks to normal. The experiment is the first to show that sharks can indeed sniff their way back home.
諾薩爾認為這些鯊魚最終都能夠回到家。“即使這些嗅覺受到限制的鯊魚並未靠近海岸，同時它們的航線非常曲折，但他們仍在向海岸游行。總體而言，它們比開始時離海岸的位置近了。”這些棉花球最終會失效，鯊魚的嗅覺就會恢復正常。此實驗首次驗證鯊魚是靠嗅覺找到回家的路。

But it also shows that they must have some kind of back-up system that lets them that lets them navigate non-nasally. For Nosal, the next questions are: What's the back-up system? And if sharks navigate by smell, what exactly is it they're smelling that leads them—by the nose.
但是，此實驗也表明，鯊魚必須擁有一些在嗅覺失靈時進行導航的備用系統。諾薩爾的下一個問題是，那麼這些備用系統是什麼?如果鯊魚利用嗅覺導航，它們到底用鼻子在聞什麼。