国家地理:Explorer: Ultimate Shark 终极者——鲨鱼

What exactly is the power that drives nature's most famous jaws²? In New Zealand, this great white shark drowned in a fisherman's net. And scientists Kara Yopak and Clinton Duffy are preparing an ultra-rare great white shark dissection³.

"Ah, I've never dissected⁴ one that is the size before."

It's a unique opportunity to study a great white's near-perfect design, including its fearsome jaws.

"The jaws of great white are really, really valuable. So most of the time, if we do get a specimen⁵ to measure, it looks a little bit more like this. Not nearly as pretty. That fishermen know pretty much. We're catching⁶ animal of, yes, for, um, a fishing competition or even just in its net. Um, we'll remove the jaws and quite often its fins⁸ as well. The jaws are amazingly valuable. Uh, they can go anywhere, from ten to twenty thousand dollars. Um, you can see them, I mean, being sold on eBay. It's kind of such a status symbol. Everybody knows the great white shark. When you have an idea of shark in your head, it's gonna be this one."

Look at the jaws.

The jaws of a great white are evolutionary⁹ marvel¹⁰. They actually burst forward, allowing for a bite that shears¹¹ up to 30 pounds of flesh in a single mouthful. About 50 teeth lie in the front of a great white's jaws. The lower teeth act like daggers¹², stabbing and holding prey¹³ in place. The larger upper teeth are like steak knives, slicing off giant mouthfuls of a victim. And behind this front row of teeth are literally¹⁴ hundreds of others, ready to be pressed into service. But to truly understand this extreme design, you have to go beneath the skin.

Unlike human beings, the great white's jaws aren't fused to the skull¹⁵. They hang loosely underneath¹⁶ the braincase, ready to execute their signature bite. First, the snout rises and opens the mouth. At the same time, the lower jaw¹ pushes down, widening the gape¹⁷. Next, special muscles in grooves¹⁸ in the skull push the upper jaw forward, exposing gums and teeth. The lower jaw rises, latching¹⁹ onto the prey, and the snout slams down, hammering the upper jaw with almost 700 pounds of force.

These extraordinary teeth are clearly designed to kill, but they may also serve another purpose: delivering a message to other great whites.

"She actually has some scarring out here. You can see where this scar's coming down, turn around underneath the eye. The ones on the side of a pectoral fin⁷, they appear to be shark bites. This one is likely to be a tooth mark, possibly another shark. These guys are not necessarily one big happy family when they get together."

Great whites can be covered in battle scars. It's believed they bite one another to assert dominance, compete for a meal and even to mate.

"How these guys get together, of course, and don't kill each other is an, it's a really interesting question."

braincase: The part of the skull that encloses the brain; the cranium. Also called brainpan

snout: The projecting nose, jaws, or anterior facial part of an animal's head

pectoral fin: Either of the anterior pair of fins attached to the pectoral girdle of fishes, corresponding to the forelimbs of higher vertebrates

1 jaw   

n.颚，颌，说教，流言蜚语；v.喋喋不休，教训

参考例句：

• He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
• A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

2 jaws   

n.口部；嘴

参考例句：

• The antelope could not escape the crocodile's gaping jaws. 那只羚羊无法从鱷鱼张开的大口中逃脱。
• The scored jaws of a vise help it bite the work. 台钳上有刻痕的虎钳牙帮助它紧咬住工件。

3 dissection   

n.分析；解剖

参考例句：

• A dissection of your argument shows several inconsistencies.对你论点作仔细分析后发现一些前后矛盾之处。
• Researchers need a growing supply of corpses for dissection.研究人员需要更多的供解剖用的尸体。

4 dissected   

adj.切开的，分割的，（叶子）多裂的v.解剖（动物等）( dissect的过去式和过去分词 )；仔细分析或研究

参考例句：

• Her latest novel was dissected by the critics. 评论家对她最近出版的一部小说作了详细剖析。
• He dissected the plan afterward to learn why it had failed. 他事后仔细剖析那项计划以便搞清它失败的原因。 来自《简明英汉词典》

5 specimen   

n.样本，标本

参考例句：

• You'll need tweezers to hold up the specimen.你要用镊子来夹这标本。
• This specimen is richly variegated in colour.这件标本上有很多颜色。

6 catching   

adj.易传染的，有魅力的，迷人的，接住

参考例句：

• There are those who think eczema is catching.有人就是认为湿疹会传染。
• Enthusiasm is very catching.热情非常富有感染力。

7 fin   

n.鳍；(飞机的)安定翼

参考例句：

• They swim using a small fin on their back.它们用背上的小鳍游动。
• The aircraft has a long tail fin.那架飞机有一个长长的尾翼。

8 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句

9 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

10 marvel   

vi.(at)惊叹vt.感到惊异；n.令人惊异的事

参考例句：

• The robot is a marvel of modern engineering.机器人是现代工程技术的奇迹。
• The operation was a marvel of medical skill.这次手术是医术上的一个奇迹。

11 shears   

n.大剪刀

参考例句：

• These garden shears are lightweight and easy to use.这些园丁剪刀又轻又好用。
• With a few quick snips of the shears he pruned the bush.他用大剪刀几下子就把灌木给修剪好了。

12 daggers   

匕首，短剑( dagger的名词复数 )

参考例句：

• I will speak daggers to her, but use none. 我要用利剑一样的话刺痛她的心，但绝不是真用利剑。
• The world lives at daggers drawn in a cold war. 世界在冷战中剑拨弩张。

13 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

14 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

15 skull   

n.头骨；颅骨

参考例句：

• The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
• He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。

16 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。

17 gape   

v.张口，打呵欠，目瞪口呆地凝视

参考例句：

• His secretary stopped taking notes to gape at me.他的秘书停止了记录，目瞪口呆地望着我。
• He was not the type to wander round gaping at everything like a tourist.他不是那种像个游客似的四处闲逛、对什么都好奇张望的人。

18 grooves   

n.沟( groove的名词复数 )；槽；老一套；（某种）音乐节奏v.沟( groove的第三人称单数 )；槽；老一套；（某种）音乐节奏

参考例句：

• Wheels leave grooves in a dirt road. 车轮在泥路上留下了凹痕。 来自《简明英汉词典》
• Sliding doors move in grooves. 滑动门在槽沟中移动。 来自《现代汉英综合大词典》

19 latching   

n.闭塞；闭锁；关闭；闭塞装置v.理解( latch的现在分词 )；纠缠；用碰锁锁上（门等）；附着（在某物上）

参考例句：

• They have a reputation for latching onto all the latest crazes. 大家都知道他们对所有的最新时尚都有兴趣。 来自《简明英汉词典》
• Sometimes we should tolerate people's mistakes instead of latching on to them. 有的时候我们要能够容错，不要揪着对方的失误不放。 来自互联网