射水鱼的喷水技能超乎想象-凯发k8官网

射水鱼的喷水技能超乎想象
文章来源:未知 文章作者:enread 发布时间:2014-09-05 06:29 字体: [ ] 
(单词翻译:双击或拖选)
archerfish hunt by shooting jets of water at unsuspecting insects, spiders, or even small 1 on leaves or 2 above, knocking them into the water below before gobbling them up. now, a study in the cell press journal current biology on september 4 finds that those fish are much more 3 and skillful target-shooters than anyone had given them credit for. the fish really do use water as a tool, the researchers say, making them the first known tool-using animal to adaptively change the hydrodynamic properties of a free jet of water. it's rather easy to see the usefulness of their impressive skill.
 
"the predominant impression from our field work in thailand over several years is that there is very little to actually shoot at, so it's important for the fish to be efficient," says stefan schuster of the university of bayreuth in germany. "it pays to be able to powerfully hit 4 over a wide range of distances."
 
schuster and peggy gerullis made the discovery by first training fish to hit targets ranging in height from 20 to 60 centimeters from a precise location. they then monitored various aspects of jet production and propagation as the fish did their thing.
 
those studies showed that the time needed before water masses up at the jet tip isn't 5. rather, archerfish make adjustments to ensure that a nice drop of water forms just before impact. surprisingly, the researchers report, the fish achieve this by 6 the 7 of changes in the cross-section of their mouth opening. the 8 adjustments that archerfish must make to powerfully hit their targets over an extended range are surprisingly comparable to the "uniquely human" ability of powerful throwing, the researchers write.
 
"one of the last strongholds of human uniqueness is our ability to powerfully throw stones or spears at distant targets," schuster says. "this is really an impressive 9 and requires -- among many fascinating aspects -- precise time control of movement. it is believed that this ability has forced our brains to become bigger, housing many more neurons to afford the precision. with the many neurons around, they could be used for other tasks apart from applying them for powerful throws. it is 10 that the same line of reasoning could also be 11 to archerfish."
 
it's possible that the 12 the fish use to control water with such precision might also find application in human-built nozzles, he adds, noting that 13 jets are big business in many industries, including medicine.
 
"the biggest problem is how to modify the 14 properties of a jet," schuster says. "usually this is done by modulating the release pressure or by varying the 15 added to the jet. we are not aware of someone actually using a dynamically adjustable valve."


点击收听单词发音收听单词发音  

1 9e3fa64f20794483b9c33d06297dcbfb     
n.蜥蜴( lizard的名词复数 )
参考例句:
  • nothing lives in pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外,没有别的生物。 来自辞典例句
  • can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗? 来自辞典例句
2 17ff1ed5da672aa443a4f6befce8e2cb     
细枝,嫩枝( twig的名词复数 )
参考例句:
  • some birds build nests of twigs. 一些鸟用树枝筑巢。
  • willow twigs are pliable. 柳条很软。
3 vjdyi     
adj.能适应的,适应性强的,可改编的
参考例句:
  • he is an adaptable man and will soon learn the new work.他是个适应性很强的人,很快就将学会这种工作。
  • the soil is adaptable to the growth of peanuts.这土壤适宜于花生的生长。
4 g1czh     
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。
5 jskzzj     
adj.固定的,不变的,准备好的;(计算机)固定的
参考例句:
  • have you two fixed on a date for the wedding yet?你们俩选定婚期了吗?
  • once the aim is fixed,we should not change it arbitrarily.目标一旦确定,我们就不应该随意改变。
6 3831b0b9165a263a37199f6886a6a3ff     
调整( modulate的现在分词 ); (对波幅、频率的)调制; 转调; 调整或改变(嗓音)的音调
参考例句:
  • in his horn solo,he kept modulating from key to key. 他在喇叭独奏时不断地变调。
  • water vapour and clouds are the primary variables modulating direct solar absorption. 水汽和云是调节直接太阳吸收的主要要素。
7 nuszqq     
n.力学,动力学,动力,原动力;动态
参考例句:
  • in order to succeed,you must master complicated knowledge of dynamics.要取得胜利,你必须掌握很复杂的动力学知识。
  • dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。
8 rguzgc     
n.时间安排,时间选择
参考例句:
  • the timing of the meeting is not convenient.会议的时间安排不合适。
  • the timing of our statement is very opportune.我们发表声明选择的时机很恰当。
9 jsgzz     
n.能力;才能;(pl)可发展的能力或特性等
参考例句:
  • she has the capability to become a very fine actress.她有潜力成为杰出演员。
  • organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。
10 8vbx6     
adj.显著的,异常的,非凡的,值得注意的
参考例句:
  • she has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
  • these cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。
11 tz2zxa     
adj.应用的;v.应用,适用
参考例句:
  • she plans to take a course in applied linguistics.她打算学习应用语言学课程。
  • this cream is best applied to the face at night.这种乳霜最好晚上擦脸用。
12 zcwxr     
n.机械装置;机构,结构
参考例句:
  • the bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • the mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
13 vzozkc     
adj.可调整的,可校准的
参考例句:
  • more expensive cameras have adjustable focusing.比较贵的照相机有可调焦距。
  • the chair has the virtue of being adjustable.这种椅子具有可调节的优点。
14 3ydz3     
adj.使表面磨损的;粗糙的;恼人的
参考例句:
  • his abrasive manner has won him an unenviable notoriety.他生硬粗暴的态度让他声名狼藉。
  • she had abrasions to her wrists where the abrasive rope had scraped her.她的手腕有多出磨伤,那是被粗糙的绳子擦伤的。
15 e65100847db55bc695b9577a4c0a57ba     
(研)磨料,磨蚀剂( abrasive的名词复数 ); 磨蚀岩屑
参考例句:
  • the most common finishing operations are mechanical, such as milling, grinding, or polishing with abrasives. 最普通的精加工工序是用机械的方法,如研磨,磨削或用磨料抛光。
  • many of these products contain mild abrasives, chemicals or polishing agents. 许多这些产品都含有微量的腐蚀剂,化学物或抛光剂。
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