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The snout of a shark is covered in tiny pores called Ampullae of Lorenzini, which convert electrical impulses in the water to an electrical signal in the shark's nerves.
鲨鱼的鼻子上覆盖着一种叫做劳伦氏壶腹的小孔，这种小孔能将水中的电脉冲转换成鲨鱼神经中的电信号。
Therefore the shark can "feel" extremely tiny electrical currents in the water--a skill it uses to hunt, even in complete darkness.
因此，鲨鱼可以“感觉到”水中极其微小的电流——这种技能能帮助鲨鱼甚至在完全黑暗的环境中捕猎。
Speaking of darkness, many people believe that sharks have poor eyesight. Not true!
说到黑暗，很多人认为鲨鱼的视力很差。不是这样的!
They don't see in color, but they have sharp eyesight, and super powerful night vision.
鲨鱼虽然看不见颜色，但它们有敏锐的视力和超强的夜视能力。
That's because they have a shiny "mirror" called the tapedum lucidem located behind the retina that reflects light back through the retina a second time, increasing its sensitivity.
这是因为鲨鱼视网膜后面有一个闪亮“镜子”，我们称之为“光神经纤维层”，它能第二次将光线反射回视网膜，增加了视网膜的敏感度。
Many sharks like to hunt at dawn, dusk and night, because they can see their prey much better than the prey can see them.
许多鲨鱼喜欢在黎明、黄昏和夜晚捕猎，因为它们能比猎物看得更清楚。
Sharks are also the only fish to have eyelids.
鲨鱼也是唯一有眼睑的鱼类。
They're called nictitating membranes and sharks use them to protect their eyes when something gets too close.
它们被称为瞬膜，当有东西靠得太近时，鲨鱼利用瞬膜来保护眼睛。
Sharks never need to go to a dentist, since they don't really care about cavities.
鲨鱼根本不需要去看牙医，因为它们根本不在乎蛀牙。
They have many rows of teeth. As old teeth break or become too dull, they fall out and new ones rotate into place.
鲨鱼有很多排牙齿。当旧的牙齿断裂或变得太钝时，就会脱落，新的牙齿就会旋转到位。
For the entire life of a shark, it never runs out of new teeth, and it never worries about the teeth it has.
鲨鱼的一生中从不缺新牙，也从不担心自己的牙齿。
And you may find this hard to believe, but sharks are really important in the ecosystems of the ocean.You'll never see a fish that needs glasses.
你可能觉得这难以置信，但是鲨鱼在海洋生态系统中真的很重要。你永远看不到一条需要眼镜的鱼。
That's because a nearsighted fish would quickly be devoured by a shark.
那是因为近视的鱼很快就会被鲨鱼吃掉。
So sharks help keep fish populations healthy by weeding out the sick and the weak.
因此，鲨鱼通过清除生病和虚弱的鱼类来保持鱼群的健康。
Healthy fish can get away from sharks, so they reproduce and make more fish.
健康的鱼可以摆脱鲨鱼，繁衍生息。
As top predators, sharks have an important role to play.
作为顶级掠食者，鲨鱼扮演着重要的角色。
And because they do not reproduce quickly, sharks are vulnerable to overfishing.
而且由于它们繁殖速度不快，鲨鱼很容易过度捕捞。
And while many people are afraid of sharks, most do not represent a threat to people at all.
虽然许多人害怕鲨鱼，但大多数鲨鱼对人类根本构不成威胁。
The world's largest shark, the Whale shark, grows larger than a bus, but eats only plankton and small fish.
世界上最大的鲨鱼——鲸鲨，比公共汽车还大，但只吃浮游生物和小鱼。
Even mean looking sharks with pointy teeth like the Sand Tiger shark prefer to eat fish and never attack people.
即使是像沙虎鲨那样长着尖牙的鲨鱼也喜欢吃鱼，从不攻击人类。
The more we learn about sharks, the more we discover how little we know about them.
我们对鲨鱼了解得越多，就越发现我们对它们知之甚少。
Even the idea of a feeding frenzy isn't really true.
甚至我们认为鲨鱼疯狂进食的想法也是不对的。
I get up close to sharks all the time while they are feeding and I have never been bitten.
鲨鱼觅食的时候，我总是靠近它们，我从来没有被鲨鱼咬过。
This group of over 30 Caribbean reef sharks is competitively feeding on a frozen chum ball.
这群超过30只的加勒比礁鲨正在争夺狗鲑。
They are all around me, but they are not interested in biting me.
它们就在我周围，但它们并没有兴趣咬我。
They know that there is food available, and I'm not it, so I just sit back and enjoy watching the action.
他们知道那里有食物，但并不是我，所以我只是在后面观看。
And when all the bait is gone, the action is over, and I'm perfectly fine.
当所有的诱饵都没了，行动就结束了，我完好无损。
Far from being the horrific monsters of legends, sharks are actually highly evolved and sophisticated animals with a range of senses and abilities unmatched in the animal world.
鲨鱼远非传说中可怕的怪物，实际上是高度进化和复杂的动物，它拥有动物世界无法比拟的各种感官和能力。
The study of sharks may teach us many things about our world and maybe even about ourselves.
对鲨鱼的研究可以教会我们很多关于我们这个世界，甚至可能关于我们自己的事情。
