官方APP下载:英语全能特训(微信小程序版,支持苹果手机、安卓手机)
创办于2003年
UNSV记不住?那就记中文谐音“忧安思危”吧!
  Slow and Steady Wins the Race!
UNSV英语学习频道 - Slow and steady wins the race!
公众微信服务号
英语全能特训(微信公众服务号)
UNSV英语学习频道淘宝网店
客服短信:18913948480
客服邮箱:web@unsv.com
初级VIP会员
全站英语学习资料下载。
¥98元/12个月

Scientists: Spiders Use Electric Fields to Move through Air

阅读次数:


VIP会员专享下载:(非VIP会员无权下载!如果想下载,但还不是VIP会员,请点此订购
下载方式:使用鼠标右键(注意是鼠标右键!)点击下面的MP3音频/MP4视频链接,然后选择“另存为…”。
MP3节目录音 MP3节目录音 
文章原文
同步字幕

Scientists have long wondered how spiders can use the webbing they make to fly.

The 19th century English naturalist Charles Darwin commented on their behavior when very small spiders landed on his ship, the HMS Beagle. He noted that they were following lines of smooth silk. He thought the creatures might have been using warm air to take to the sky. However, new research shows a totally different cause may be involved.

Erica Morley and Daniel Robert are with the University of Bristol in Britain. They were interested in exploring another explanation for the spiders’ ability. They thought spiders might sense and use electrostatic fields in the air.

Morley told VOA: “There have been several studies looking at how air movement and wind can get spiders airborne, but the electrostatic hypothesis was never tested.”

But some observers suggested electrostatic fields might be the reason the many draglines some spiders use to float never get tangled.

Kimberley Sheldon is a biologist with the University of Tennessee, Knoxville, in the United States. She said that although “these spiders will have 5 or 6 draglines, those strands of silk do not get entangled. So, we've known for a while that electrostatics probably [are] at least interacting with the spider, with the silk lines themselves to keep them from getting tangled.”

FILE - A spider sits in her web. Researchers from England think spiders might be sensing and using electrostatic fields to become airborne.
FILE - A spider sits in her web. Researchers from England think spiders might be sensing and using electrostatic fields to become airborne.

Sheldon was not involved in the latest study.

Morley and Robert created a box with a grounded metal plate on the bottom and a plate on the top. It was designed so they could send an electrical current through the box. They placed spiders inside the box and turned on the electricity, then watched as the spiders reacted to the electric field.

When the electric field was on, the spiders lifted their abdomens into the air and started raising up on the very ends of their legs. Morley told VOA that spiders only move this way before they release silk draglines to fly away, in a process called ballooning.

When the spiders did balloon and rise into the air, turning off the electric current caused them to drop.

Sheldon compares this to someone taking a balloon and rubbing it against their clothing. 'If you hold the balloon [near your head], your hair stands on end. That's kind of what's happening with the spider silk.”

Clearly the spiders were able to sense the local electrostatic field and react by releasing silk, but Morley and Robert wanted to know how.

Morley noted that as a sensory biologist, she was interested in understanding what sensory system spiders might use to sense electric fields.

“We know that they have very sensitive hairs that are displaced by air movements or even sound. So, I thought that it’s possible that they might be using these same hairs to detect electric fields,” she said.

This was exactly what she observed. The small hairs along the spiders’ legs react not only to physical experiences like air movement, but also to the electric field. In nature, it makes sense for spiders to sense both the electrostatic field around them as well as wind conditions. Spiders probably use both when taking off and moving through the sky.

Mathematician Longhua Zhao is with Case Western Reserve University in Cleveland, Ohio. She has made computer models of how spiders balloon. She told VOA that both the electrical field and the air flow are important.

“They definitely play very important roles; however, we don’t know at this point, which is the dominant factor,” she added.

Lead researcher Morley pointed out that spiders are not the only creatures to balloon. “Caterpillars and spider mites, which are arachnids but not spiders, balloon as well,” she noted.

Arachnids have eight legs and a body made of two parts.

Invertebrates have no back bone.

Morley hopes other researchers will follow up her study to see if these other creatures react in much the same way as spiders.

I’m Pete Musto.

Sadie Witkowski reported this story for VOANews.com. Phil Dierking adapted her story for Learning English. George Grow was the editor.

Are there any animal behaviors you are curious about? Write to us in the Comments Section or on our Facebook page.

Words in This Story

abdomen - n. the part of the body below the chest that contains the stomach and other organs​

dragline - n. a rope used for dragging or hauling something.

electrostatic - adj. relating to stationary electric charges or fields as opposed to electric currents.​

factor - n. something that helps produce or influence a result​

hypothesis - n. an idea or theory that is not proven but that leads to further study or discussion​

plate - n. a thin, flat piece of metal​

role - n. a part that someone or something has in a particular activity or situation

silk - n. a smooth, soft, and shiny cloth that is made from thread produced by silkworms​

tangle - v. to become or cause (something) to become twisted together​

webbing - n.

网友的学习评论(0条):
版权所有©2003-2019 南京通享科技有限公司,保留所有权利。未经书面许可,严禁转载本站内容,违者追究法律责任。 互联网经营ICP证:苏B2-20120186
网站备案:苏ICP备05000269号-1中国工业和信息化部网站备案查询
广播台