Featured Research

from universities, journals, and other organizations

It's A Bug's Life: MIT Team Tells Moving Tale

Date:
September 29, 2005
Source:
Massachusetts Institute of Technology
Summary:
MIT mathematicians have discovered how certain insects can climb what to them are steep, slippery slopes in the water's surface without moving their limbs -- and do it at high speed. Welcome to the world of the tiny creatures that live on the surface of ponds, lakes and other standing bodies of water. There, "all the rules change," said David Hu, a graduate student in the Department of Mathematics and first author of a paper on the work to appear in the Sept. 29 issue of Nature.

The larva of a waterlily leaf beetle gets ready to propel itself up onto a leaf using a technique recently discovered by MIT researchers.
Credit: Photo courtesy Hu and Bush, 2005

MIT mathematicians have discovered how certain insects can climb what to them are steep, slippery slopes in the water's surface without moving their limbs -- and do it at high speed.

Welcome to the world of the tiny creatures that live on the surface of ponds, lakes and other standing bodies of water. There, "all the rules change," said David Hu, a graduate student in the Department of Mathematics and first author of a paper on the work to appear in the Sept. 29 issue of Nature.

For the last four years, Hu and John Bush, an associate professor in the department, have been studying the novel strategies these insects use to navigate their environment. To do so, they took high-speed video of the creatures using a camera provided by MIT's Edgerton Center, then digitized and analyzed the images.

In 2003, the two and Brian Chan, a graduate student in the Department of Mechanical Engineering, reported in Nature how some of these creatures walk on water. Both that paper and the current one were Nature cover stories.

Now Bush and Hu are describing how three species of insects are able to climb the slippery slopes, or menisci, that arise when the water surface meets land, floating bodies or emergent vegetation.

Why would they want to leave the water? "There are many reasons, such as laying eggs or escaping predators," said Hu.

Menisci are all around us--picture the slight upward curve of water in a glass where it meets the side. "But we don't notice them because they're so small, only a few millimeters in height," said Hu. But if you're a creature that's much smaller than that, those slopes "are like frictionless mountains," Hu said. "Plus, it's slippery."

In these conditions, the insects' normal modes of propulsion won't work. Hu and Bush took high-speed video of insects trying to ascend menisci with a running start and found they got partway up, then slid back down.

The solution? The creatures adopt special postures that create forces that pull them up the slope at speeds of almost 30 body lengths per second (for comparison, an Olympian sprinter moves at about five body lengths per second).

For example, Hu and Bush found that two species of water treaders have retractable claws on their front and hind legs that allow them to "grasp" the surface of the water and pull it into a miniscule peak. The insect simultaneously presses down on the water with its central pair of legs, forming dimples in the water surface that bear the creature's weight.

Because the insects are so small, these perturbations create forces that suck them up the slope, similar to the way champagne bubbles rise to the edge of a glass.

Bush explains that the insect is actually "generating tiny menisci" with its front and hind legs. Since menisci are attracted to other menisci, the cumulative effect is to pull the insect up and over the meniscus at the water's edge.

Remember the champagne bubbles? Each essentially forms its own meniscus, hence the attraction to the edge of the glass.

The larva of the waterlily leaf beetle solves the same problem a different way. The sluglike creature simply arches its back, creating menisci at each end. The effect has the same end result, propelling the larva up the slope.

Bush and Hu got involved in this work because they wanted to explain how these creatures do what they do. Bush notes, however, that "the physics is also of interest to people working in nanotechnology because they, too, are concerned with problems at very small length scales."

Hu will be defending his thesis on Sept. 28.

This work was sponsored by the National Science Foundation.


Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts Institute of Technology. "It's A Bug's Life: MIT Team Tells Moving Tale." ScienceDaily. ScienceDaily, 29 September 2005. <www.sciencedaily.com/releases/2005/09/050929082253.htm>.
Massachusetts Institute of Technology. (2005, September 29). It's A Bug's Life: MIT Team Tells Moving Tale. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2005/09/050929082253.htm
Massachusetts Institute of Technology. "It's A Bug's Life: MIT Team Tells Moving Tale." ScienceDaily. www.sciencedaily.com/releases/2005/09/050929082253.htm (accessed April 24, 2014).

Share This



More Plants & Animals News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Fungus Killing Bats, Spreading in US

Deadly Fungus Killing Bats, Spreading in US

AP (Apr. 24, 2014) — A disease that has killed more than six million cave-dwelling bats in the United States is on the move and wildlife biologists are worried. White Nose Syndrome, discovered in New York in 2006, has now spread to 25 states. (April 24) Video provided by AP
Powered by NewsLook.com
Blood From World's Oldest Woman Suggests Life Limit

Blood From World's Oldest Woman Suggests Life Limit

Newsy (Apr. 24, 2014) — Scientists say for the extremely elderly, their stem cells might reach a state of exhaustion. This could limit one's life span. Video provided by Newsy
Powered by NewsLook.com
Raw: Kangaroo Rescued from Swimming Pool

Raw: Kangaroo Rescued from Swimming Pool

AP (Apr. 24, 2014) — A kangaroo was saved from drowning in a backyard suburban swimming pool in Australia's Victoria state on Thursday. Australian broadcaster Channel 7 showed footage of the kangaroo struggling to get out of the pool. (April 24) Video provided by AP
Powered by NewsLook.com
Could Marijuana Use Lead To Serious Heart Problems?

Could Marijuana Use Lead To Serious Heart Problems?

Newsy (Apr. 24, 2014) — A new study says marijuana use could lead to serious heart-related complications. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins