Hot secret behind toucan's bill 犀鸟喙发热的秘密
文章来源:未知 文章作者:meng 发布时间:2009-07-24 05:52 字体: [ ]  进入论坛

For centuries, scientists have puzzled over why the toucan1's bill is so remarkably2 large - but now one team thinks it might have an answer.


As the surroundings heat up, the <a href=toucans3 dump body heat into their bills" width="226" border="0" src="/upimg/090724/4_055418_1.jpg" />
As the surroundings heat up, the toucans dump body heat into their bills

Writing in the journal Science, the researchers say that the toucan uses its enormous beak4(鸟嘴) to stay cool.

They used infrared5 cameras(红外摄像机) to show the bird dumping heat from its body into its bill, helping6 it to regulate its body temperature.

The toucan has the largest bill of any bird, relative to body size.

It makes up about one-third of its total body length.

Hot secrets

The oversize appendage7(附加物) has received many different interpretations8(解释): Charles Darwin thought it might be used to attract mates, more recent ideas centre on fruit peeling, nest predation(掠夺行为) and visual warnings.

To investigate further, a team of researchers from Brock University, Canada, and Universidade Estadual Paulista, Brazil, looked at the toco toucan (Ramphastos toco), which has the biggest bill of all the toucans.

Dr Glenn Tattersall, the lead author of the paper, from Brock University, Canada, said: "We used infrared thermal9 imaging technology to assess the surface temperature of the bill of toucans while they were encountering a range of air temperatures from 10C to 35C.

"This allowed us to measure the exact temperature of the bill."

The scientists found that as the surroundings got warmer, the toucan's bill would rapidly heat up, effectively acting10 as a radiator11 to draw heat away from the bird's body, allowing it to stay cool.

Conversely, in cooler temperatures, little heat would radiate from the bill, letting the bird conserve12 its warmth.

The effect was particularly evident at night: at sunset, the birds would, in a matter of minutes, pump out heat from their beaks13, lowering their body temperature as they slept.

The birds' bills have a network of blood vessels14 that can increase or restrict the flow of blood.

Dr Tattersall said: "By altering blood flow to the bill's surface, toucans can conserve body heat when it is cold or cope with heat stress by increasing blood flow.

"Essentially15, the large surface area of the bill, and the fact it is not insulated(绝缘), means that the blood flowing through is able to release heat into the bill, thus cooling the bird.

"This blood-derived heat in the bill is then dissipated(浪费的) into the air."

Effective radiators16

Other animals also use parts of their bodies to regulate temperature, for example, elephants and rabbits radiate heat from their ears to cool down.

But the sheer size of the toucan's bill means that relatively17, it has one of the largest "thermal windows" in the animal kingdom.

The Science study also shows that the toucan is extremely effective at controlling its body heat with it: its bill can account for as much as 100% of body heat loss or as little as 5% if the blood flow is shut off.

Dr Tattersall explained: "Bird bills are not 'dead tissues', incapable18 of playing a role in heat balance, but are active contributors to thermoregulation(温度调节)."

He added: "Birds do not sweat, so must cope with other mechanisms19 to deal with elevated temperatures."

The researchers say that the finding that the toucan uses its beak to regulate body temperature does not rule its other suggested functions.

The team now plans to look at other birds to see how their bills are involved with temperature regulation.


1 toucan OgRzPt     
  • A toucan is a South American bird.巨嘴鸟是北美的一种鸟。
  • There is a toucan in this zoo.这个动物园有一只巨嘴鸟。
2 remarkably EkPzTW     
  • I thought she was remarkably restrained in the circumstances. 我认为她在那种情况下非常克制。
  • He made a remarkably swift recovery. 他康复得相当快。
3 toucans 1bed8326dd2ce6bc3b3e4bb405c5a491     
n.巨嘴鸟,犀鸟( toucan的名词复数 )
  • Against it, parakeets and toucans and blue-winged macaws swoop. 晨光下,小鹦鹉、巨嘴鸟和翅膀鲜蓝的金刚鹦鹉展翼翱翔。 来自互联网
  • Toucans also have a narrow, feather-like tongue. 巨嘴鸟也有狭窄部份,像羽毛一样的舌。 来自互联网
4 beak 8y1zGA     
  • The bird had a worm in its beak.鸟儿嘴里叼着一条虫。
  • This bird employs its beak as a weapon.这种鸟用嘴作武器。
5 infrared dx0yp     
  • Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
6 helping 2rGzDc     
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
7 appendage KeJy7     
  • After their work,the calculus was no longer an appendage and extension of Greek geometry.经过他们的工作,微积分不再是古希腊几何的附庸和延展。
  • Macmillan must have loathed being judged as a mere appendage to domestic politics.麦克米伦肯定极不喜欢只被当成国内政治的附属品。
8 interpretations a61815f6fe8955c9d235d4082e30896b     
n.解释( interpretation的名词复数 );表演;演绎;理解
  • This passage is open to a variety of interpretations. 这篇文章可以有各种不同的解释。 来自《简明英汉词典》
  • The involved and abstruse passage makes several interpretations possible. 这段艰涩的文字可以作出好几种解释。 来自《现代汉英综合大词典》
9 thermal 8Guyc     
  • They will build another thermal power station.他们要另外建一座热能发电站。
  • Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
10 acting czRzoc     
  • Ignore her,she's just acting.别理她,她只是假装的。
  • During the seventies,her acting career was in eclipse.在七十年代,她的表演生涯黯然失色。
11 radiator nTHxu     
  • The two ends of the pipeline are connected with the radiator.管道的两端与暖气片相连接。
  • Top up the radiator before making a long journey.在长途旅行前加满散热器。
12 conserve vYRyP     
  • He writes on both sides of the sheet to conserve paper.他在纸张的两面都写字以节省用纸。
  • Conserve your energy,you'll need it!保存你的精力,你会用得着的!
13 beaks 66bf69cd5b0e1dfb0c97c1245fc4fbab     
n.鸟嘴( beak的名词复数 );鹰钩嘴;尖鼻子;掌权者
  • Baby cockatoos will have black eyes and soft, almost flexible beaks. 雏鸟凤头鹦鹉黑色的眼睛是柔和的,嘴几乎是灵活的。 来自互联网
  • Squid beaks are often found in the stomachs of sperm whales. 经常能在抹香鲸的胃里发现鱿鱼的嘴。 来自互联网
14 vessels fc9307c2593b522954eadb3ee6c57480     
n.血管( vessel的名词复数 );船;容器;(具有特殊品质或接受特殊品质的)人
  • The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
  • All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》
15 essentially nntxw     
  • Really great men are essentially modest.真正的伟人大都很谦虚。
  • She is an essentially selfish person.她本质上是个自私自利的人。
16 radiators 3b2bec7153ad581082a64cd93346b77f     
n.(暖气设备的)散热器( radiator的名词复数 );汽车引擎的冷却器,散热器
  • You can preset the radiators to come on when you need them to. 你可以预先调好暖气,使它在你需要的时候启动。
  • Stars are radiators of vast power. 恒星是强大的发光体。 来自《现代英汉综合大词典》
17 relatively bkqzS3     
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
18 incapable w9ZxK     
  • He would be incapable of committing such a cruel deed.他不会做出这么残忍的事。
  • Computers are incapable of creative thought.计算机不会创造性地思维。
19 mechanisms d0db71d70348ef1c49f05f59097917b8     
n.机械( mechanism的名词复数 );机械装置;[生物学] 机制;机械作用
  • The research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
  • He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》
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