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When you think of a shark, what do you picture in your mind?
你想到鲨鱼时，脑海里是什么画面？
Do you think of a big thing sticking out of the water or maybe a huge set of sharp teeth?
你想到的是从水里伸出来的巨物还是一排巨大的尖牙？
Sharks are some of the most famous animals in the ocean.
鲨鱼是海洋里最著名的生物之一。
But do you know what makes a shark? A shark?
但你知道什么造就了鲨鱼吗？
Well, for one thing, all sharks are fish.
首先，所有的鲨鱼都是鱼。
That might not surprise you since they live and swim in the water.
你可能不会惊讶，因为它们在水里生活游动。
But sharks are a special kind of fish.
但鲨鱼是一种特殊的鱼。
One of the things that make them different from other fish like goldfish is that sharks have a special skeleton.
它们与金鱼等其他鱼不同的地方是鲨鱼的骨骼特殊。
Our skeletons are made of bone and so are the skeletons of most kinds of fish.
我们的骨骼是由骨头构成的，大多数种类的鱼也是如此。
But a shark skeleton isn't made of bone, it's made of cartilage.
但鲨鱼的骨骼不是由骨头构成的，而是软骨。
And you have cartilage in your body, too.
你身体里也有软骨。
You can feel it right now.
你现在就可以感受一下。
Touch the tip of your nose, wiggling around. How's it feel?
摸摸你的鼻尖，左右摆摆。感觉如何？
What about your ear? Can you bend it?
那么你的耳朵呢？你能使它弯曲吗？
You sure can. Because the tip of your nose and your ear aren't filled with bone.
当然能。因为你的鼻尖和耳朵不是骨头。
They're filled with cartilage.
它们是由软骨构成的。
Cartilage is a lot lighter than bone and it bends easily.
软骨比骨头轻很多，也容易弯曲。
So having a skeleton made of this stuff help sharks swim further and faster than if their skeletons were made of bone .
所以由这种物质构成的骨骼能帮助鲨鱼游得更远也更快。
Now, let's look at another body part that sharks are famous for. Their teeth.
现在，我们看看鲨鱼出名的另一个身体部位。它们的牙齿。
Have you ever lost a baby tooth and then an adult tooth grew in？
你曾经掉过乳牙，而后长出来固齿吗？
Well, sharks lose their teeth all the time throughout their entire lives and they just keep growing new ones.
鲨鱼一生一直在掉牙，然后又不断长出新牙。
How can they do that?
它们怎么做到的？
You and I just have one row of teeth in our mouths,
你我的嘴里只有一排牙齿，
but sharks have a lot of rows of teeth on the top and the bottom,
但鲨鱼在最外面和最里面有很多排牙齿，
so when a shark loses a tooth, another tooth that's right behind it can just move on up to take its place.
所以鲨鱼掉牙时，它正后面的一颗会移到前面代替它。
Because they always have new teeth to replace the old ones,
因为它们总有新牙来代替旧牙，
some sharks can lose thousands of teeth during their lives.
一些鲨鱼一生可能掉牙数千次。
Alright, the next cool thing about sharks? Their skin.
那么，鲨鱼下一个厉害的东西是什么？它的表皮。
If you could rub the skin of a shark,
如果你能摩擦鲨鱼的表皮，
you'd find that it would feel smooth if you rub your hand in one direction,
就会发现沿一个方向摩擦感觉很光滑，
but if you rub your hand the other way, it would feel rough like a cat's tongue.
但如果你用其他方式摩擦，就会感觉粗糙，就像摸猫的舌头。
That's because a shark skin is covered in tough bony scales that actually look a little like tiny teeth.
这是因为鲨鱼表皮覆盖着坚硬的盾鳞，看上去有点儿像微小的牙齿。
These little scales are stacked on top of each other like tiles on a route.
这些小鳞片堆叠在一起就像路上的瓦片一样。
This helps sharks swim through the water quickly and quietly.
它能帮助鲨鱼在水中快速安静地游动。
So those are some of the things that all sharks have.
这些东西都是鲨鱼共有的。
But there are over 450 types of sharks in the world. And that means a lot of differences too.
但世界上的鲨鱼有450多种，这就意味着它们有很多不同。
Take a look at this one, it's called a whale shark.
看看这个，它被称为鲸鲨。
And it's the bigger shark there is.
它是较大的鲨鱼。
In fact, it's the largest fish in the whole world.
事实上，它是世界上最大的鱼。
Whale sharks can grow to be as long as a school bus, but even though they're so big,
鲸鲨可以长到和校车一般长，但即使它们体型巨大，
they eat tiny plants and super small animals called plankton that flow in the water.
还是吃小植物和水里游动的浮游动物。
But not all sharks are as big as the whale shark, some can also be tiny.
但不是所有的鲨鱼都与鲸鲨一样大，有些可能很小。
Meet the dwarf lanternshark, it's so small that could fit in my hand.
见见矮子灯笼鲨吧，它很小，可以放在我的手上。
This shark lives in the deep ocean where there's very little light,
这种鲨鱼生活在没有光的深海里，
so it has big eyes to help see in the dark.
所以它有一双大眼睛，帮它在黑暗中看东西。
Plus it has a really neat feature.
另外，它还有一个非常奇特的特征。
It has special organs on its belly, fins and tail that actually glow.
它的腹部、鳍和尾巴上都有特殊的发光器官。
Scientists think this might help the lanternshark luring pray for it to eat.
科学家们认为这可能帮助它吸引被捕食者。
Plus when it's in shallow water where there's more light,
而且浅水处有更多的光，
these glowing lights can help it blend in to avoid predators.
这些发光的灯可以帮它融入环境逃避捕食者。
Finally, I'd like you to meet a very special shark.
最后，我想让你看一种非常特殊的鲨鱼。
Say hello to the Greenland shark.
和格陵兰鲨打个招呼吧。
This big shark spends most of its time swimming in very cold water,
这种大鲨鱼大部分时间都在冷水中游动，
hanging out near the sea floor, looking for an easy snack.
在海底附近闲逛，寻找简单的小吃。
But scientists have recently discovered something amazing about these animals.
但科学家们最近发现了这种动物的惊人之处。
Greenland sharks can live to be up to 400 years old.
格陵兰鲨可以活到400岁。
Of all the animals in the world with backbones, known as vertebrates,
就我们所知，在世界所有带骨的脊椎动物中，
Greenland sharks live the longest, at least that we know of.
格陵兰鲨活得最长。
But scientists are still discovering new kinds of sharks all the time.
但科学家们仍在研究鲨鱼的新种类。
So who knows what kind of super sharks are still out there waiting to be found.
所以，谁知道有什么超级鲨鱼等着被发现呢？
What's your favorite animal?
你最喜欢的动物是什么？
Do you want to learn more about it?
你对它想有更多的了解吗？
Just ask a grown-up to help you and leave a comment below,
找个大人在下方留言
or send us an email to or send us an email to kids@scishow.com.
或发邮件至kids@scishow.com。
We're excited to hear from you.
我们期待您的来信。
Oh and we're also really excited, because we're making some changes to the Fort,
噢，我们也很兴奋，我们对沃斯堡做了一些改变，
so stay tuned and we'll share a few surprises with you in the upcoming weeks.
所以请继续关注，我们将在接下来的几周与大家分享一些惊喜。
Thanks and we'll see you next time, here at the Fort!
感谢您的收看，我们下期见，沃斯堡等你哦！
