首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Birds are literally half-asleep--with one brain hemisphere alert and the other sleeping, according to a new study of sleeping du
Birds are literally half-asleep--with one brain hemisphere alert and the other sleeping, according to a new study of sleeping du
admin
2010-01-13
36
问题
Birds are literally half-asleep--with one brain hemisphere alert and the other sleeping, according to a new study of sleeping ducks.
Earlier Studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird flocks led researchers to predict extra alertness in the more vulnerable, end-of-the-row sleepers. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds dozing (打盹) at the end of the line resorted to single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Rotating 16 birds through the positions in a four-duck row, the researchers found outer birds half-asleep during 32 percent of dozing time versus about 12 percent for birds in internal spots.
"We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness simultaneously in different regions of the brain," the researchers say.
The results provide the best evidence for a long-standing supposition that single- hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the. lockout side could be widespread, he predicts. He’s seen it in a pair of birds’ dozing side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it’s only been found in birds and such water mammals (哺乳动物) as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds’ half-brain sleep "is just the tip of the iceberg (冰山) ". He speculates that more examples may turn up when we take a closer look at other species.
While sleeping, some water mammals tend to keep half-awake in order to ______
选项
A、alert themselves to the approaching enemy
B、emerge from water now and then to breathe
C、be sensitive to the ever-changing environment
D、avoid being swept away by rapid currents
答案
B
解析
由第七段可知,象海豚、鲸鱼和海豹这类的哺乳动物也经常要保持一侧大脑的清醒,这样这些睡眠的动物就可以偶尔浮出水面,以免溺水。也就是说,他们要偶尔浮出水面进行呼吸(emerge from water now and then to breathe)。
转载请注明原文地址:https://kaotiyun.com/show/Mgmi777K
0
在职申硕(同等学力)英语
相关试题推荐
Anyonewhocanstudyabroadisfortunate;but,ofcourse,itisnoteasytomakethe______fromoneculturetoanother.
Accordingtothepassage,thevolunteers______.Accordingtothelastparagraph,thetypicalvolunteernowmaybe______.
Accordingtothepassage,thevolunteers______.AllthestatementsaretrueaboutPrinceWilliamEXCEPTthat______.
Thebasisofremotediagnosiswillbe______.Theword"problem"inthefourthparagraphreferstothefactthat______.
WhichofthefollowingistrueaboutEllis?Accordingtopsychologists,successfulpeoplewholieaboutthemselves______
Aqualityeducationistheultimateliberator.Itcanfreepeoplefrompoverty,givingthemthepowertogreatlyimprovetheirl
Withoutquestion,people’slivesinChinahaveimproveddramaticallyinthepasttwodecades.
Accordingtothewriter,theshiftfrom"education"to"learning"______.Accordingtothispassage,theNewLabour’sgovernment
Accordingtothewriter,theshiftfrom"education"to"learning"______.Inthesecondparagraph,thewritersuggeststhat_____
Averyimportantworldproblemistheincreasingnumberofpeoplewhoactuallyinhabitthisplanet.Thelimitedamountoflanda
随机试题
下列属于知识产权的特征的是()。
关于缓进型高血压的描述错误的是
A.呕吐物为隔餐食物,带腐臭味B.呕吐物为黄绿色,带粪臭味C.呕吐物为大量黏液及食物D.呕吐物为血液E.吐出胃内容物后仍干呕不止急性胃炎的临床表现是
下列哪种属感染性疾病
下列关于国库单一账户体系的表述中,正确的有()。
中国证券业协会会员自收到对本单位及本单位从业人员奖励决定文书之日起()个工作日内向协会诚信管理系统申报,协会审核后记入诚信信息系统。
世界上讲述方程最早的著作是()。
儿童出现想象萌芽的时期是2~2.5岁。()
“其身正,不令而行;其身不正,虽令不从。”体现的德育方法是
A、8:30inthemorning,Tuesday.B、8:30intheevening,Tuesday.C、8:30inthemorning,Monday.D、8:30intheevening,Monday.A根
最新回复
(
0
)