Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

It’s a bug’s life: MIT team tells moving tale

29.09.2005


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.

Elizabeth Thomson | EurekAlert!
Further information:
http://www.mit.edu

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>