Fire ants assemble as a 'super-organism' (w/ video)

Apr 25, 2011 By Katharine Gammon
Ants float because of the buoyancy of the air bubbles trapped next to their bodies. A thin layer of air can be seen around its antennae and body as well. Credit: Ant Laboratory, Georgia Institute of Technology

The ants may go marching one by one, but they end up forming a superstructure of thousands -- and together they can form a raft that stretches the boundaries of the laws of physics, according to new research released today.

Ants have exoskeletons that are naturally hydrophobic, or water repellant. A single ant can walk on water because of the buoyancy of the air bubbles trapped next to its body, and the water's own surface tension. However, when thousands of ants stand on top of each other, their multiplied weight should cause them to sink. But for years, biologists have observed fire floating down flood plains and rivers in their native South America.

For the first time, a group of engineers has attacked the question of ant flotation from a physics perspective. Ants float as a group because they can harness the power of nearby air bubbles. Grasping each other's mandibles or front legs with a force 400 times their body weight, the ants are able to trap small pockets of air between them -- like a group floatation device.

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"The ants are so tightly knit together, that air pockets form between the water and the ants, and water cannot penetrate through any part," said Nathan Mlot, a graduate student at the Georgia Institute of Technology in Atlanta and one of the study's authors.

The bottom layer of ants rests on top of the water's surface, and others pile on above them. Even when they do get submerged, the pockets of air bring them back to the surface quickly -- and allow them to breathe. When they get submerged, the ants flex their muscles in unison to form a tighter weave.

To understand exactly how the structure worked, the researchers took a raft of several thousand ants and dropped it in , immediately freezing it. Then they were able to look at the structure on an ant-by-ant level under an electron-scanning microscope. "We were surprised at just how waterproof raft was -- its ability to repel water and keep afloat," said Mlot.

What if you want to drown the ants? Just add soap to the water, which greatly reduces its of water and sinks the raft, said Mlot. "With soap, the ants will drown within a matter of seconds, whereas they can survive for days or even weeks on the raft otherwise."

When fire ants are gathered into a group, they have some of the same properties as a liquid, like the ability to flow from one container to another. Credit: Ant Laboratory, Georgia Institute of Technology

To test some of the behavioral dynamics inside the pancake-shaped raft, the researchers painstakingly picked ants one by one from the top of the structure. Soon, a new one would climb from the bottom to keep the raft the same thickness.

"We know that self-assembly and self-healing are attributes of living organisms, and we have seen that ant rafts develop these on a macro scale," said Mlot. The study was published today in the journal Proceedings of the National Academy of Sciences.

"Each ant does one tiny job, but they can build these incredible structures," said Kenneth Ross, an entomologist with the University of Georgia who was not involved in the work. Ross says that the rafts include not only worker ants, but also the queen and her brood -- the reproductive cells of the giant superorganism. From what he has seen in his research, the queen usually stays in the center of the raft, with an even tighter ball of ants around her.

This level of social organization isn't common, said Joshua King, an insect ecologist at the Central Connecticut State University, in New Britain. "This study reinforces how unique the collective behaviors of social insects are when compared to other animals."

This type of research could eventually help in many fields, from making a better rain jacket to building robots that can think. When the ants link up their mandibles and legs, they form a highly waterproof weave, which could be the basis for next-generation materials for lifejackets or boats. In addition, social insects like ants have long been the inspiration for autonomous robotics that could link up to build a larger structure.

" are like little computers, acting on a few simple rules of engagement," said Mlot.

Explore further: Physics team uses pixel sensitivity of smartphone as a random generator for encryption

More information: -- Mlot, Tovey & Hu. 2011. Fire ants self-assemble into hydrophobic rafts to survive floods. PNAS , dx.doi.org/10.1073/pnas.1016658108

Ants as Fluids: Physics-Inspired Biology, Micah Streiff, Nathan Mlot, Sho Shinotsuka, Alex Alexeev, David Hu, arXiv:1010.3256v1 [physics.flu-dyn] arxiv.org/abs/1010.3256

Abstract
Fire ants use their claws to grip diverse surfaces, including each other. As a result of their mutual adhesion and large numbers, ant colonies flow like inanimate fluids. In this sequence of films, we demonstrate how ants behave similarly to the spreading of drops, the capillary rise of menisci, and gravity-driven flow down a wall. By emulating the flow of fluids, ant colonies can remain united under stressful conditions.

Provided by Inside Science News Service

4.7 /5 (18 votes)

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User comments : 20

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JRDarby
3.9 / 5 (7) Apr 25, 2011
Obligatory: I, for one, welcome our new Formicidae overlords!
TheGhostofOtto1923
4.1 / 5 (13) Apr 25, 2011
One wonders if a similar species couldnt travel through space in a similar manner by forming into spores. But how would they get there to begin with? Maybe they began in the interior of a comet? Or in an icy moon, blown into space by ice volcanos?
mthorn10
1.7 / 5 (10) Apr 26, 2011
That's cool!! Romans 1:20 For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse.
J-n
4 / 5 (6) Apr 26, 2011
It's very interesting!!

Exodus 21:20-21 When a man strikes his male or female slave with a rod so hard that the slave dies under his hand, he shall be punished. If, however, the slave survives for a day or two, he is not to be punished, since the slave is his own property.

From today forward every bible quote i see here on Physorg, i will respond to with a bible quote of my own. Same Bible Same infallibility no?
Modernmystic
3 / 5 (2) Apr 26, 2011
Maybe they began in the interior of a comet?


How the hell would that happen??

Or in an icy moon, blown into space by ice volcanos?


Far more likely than the previous...
Diggs
5 / 5 (2) Apr 26, 2011
Cool. I wonder if I can use this bunch of fire ants I dug out of my lawn to float on the surface of my pool?
Here goes...
TheGhostofOtto1923
3.8 / 5 (16) Apr 26, 2011
How the hell would that happen??
Comets may possibly contain all the materials and conditions necessary for life.
http
://www.space.com/4233-scientist-calculations-prove-life-began-comet.html

-I usually like to do a little research before posting embarrassing comments.
J-n
5 / 5 (3) Apr 26, 2011
I just try not to post embarrassing comments regardless of my research ;)
Modernmystic
3.7 / 5 (3) Apr 26, 2011
Comets may possibly contain all the materials and conditions necessary for life.


Uh yeah I know, but how is there going to be chemistry there without liquid water you moron. How is life going to "get started" on a comet?

Talk about research....

From YOUR source:

"It looks to me as if their conclusions are constructed from a series of speculations, none of which is based on much evidence. It is a theory built on air, not solidly grounded in scientific facts," said David Morrison, a senior scientist at the NASA Ames Research Center in Moffett Field, California, who was not involved in the study.


Did you even read it?
TheGhostofOtto1923
3.7 / 5 (15) Apr 26, 2011
Did you even read it?
No you picklehead. I didnt read this one either:
http://www.physor...634.html

Or this one you buttmonkey:
http://en.wikiped...mophiles

-What makes you think there cant be liquid water in slushy comets for at least part of their orbit or lifetime? Maybe you should read this one like I didnt:
http://www.scienc...1658.htm

Pootyface.
TheGhostofOtto1923
3.7 / 5 (15) Apr 26, 2011
"Recent experiments suggest that if bacteria were somehow sheltered from the radiation of space, perhaps inside a thick meteoroid or an icy comet, they could survive dormant for millions of years."

"African lungfish (Protopterus), burrow deeply into the mud when their water supply is diminished. They surround themselves with a cocoon of slime and remain inactive. Their gills are nonfunctional during this period of dormancy, and they use a lunglike air..."

-Kind of reminds you of xians in basements during times of tribulation eh? Or this:
http://www.mold.p...nium.htm
rawa1
2.3 / 5 (3) Apr 27, 2011
What if you want to drown the ants? Just add soap to the water


Surprisingly, some caterpillars really vomit detergents to wreck ant waterproofing

http: //blogs.discovermagazine.com/notrocketscience/2008/11/05/caterpillars-vomit-detergents-to-wreck-ant-waterproofing/
Modernmystic
3.7 / 5 (3) Apr 27, 2011
No you picklehead. I didnt read this one either:
http://www.physor...634.html


So a million years of chemistry and then a frozen iceball for billions of years is how life got started, that's what you're telling us?

There isn't a thing in any of your other links to suggest that life did or could have gotten started in comets. How about making an actual case for your point instead of throwing links you either don't understand or haven't read all over the board...
Skeptic_Heretic
not rated yet Apr 27, 2011
The more interesting bit, and more on the philosophical side is how does this relate to human societies and societal structures. Yet more data for emergence theory.
Medical_Intuitive
4 / 5 (1) Apr 30, 2011
WHOA! SURFACE TENSION! The report as given above ignores the obvious, to me, aspect of surface tension. Ants have no visual capacity; they are kinesthetic in NLP terms. In forming a raft, they appear to be organizing a size of raft ACCORDING TO SURFACE TENSION, organizing according to how many ant layers the surface tension can support.

What I speculate is in CLEAN WATER the surface tension can support an ant layer two ants deep allowing all ants to breathe.

YOUR RESEARCH IS NOT DONE. To test this you would need to WITH GREAT LOVING retry the experiment with ants in liquids of lower surface tension. Do not do this unless you have compassion for ants and a good reason beyond curiosity. killing ants for curiosity is not a good reason to do so.
Medical_Intuitive
1 / 5 (2) Apr 30, 2011
The APPLICATION TO HUMAN CULTURE IS OBVIOUS, so obvious the comments above appear to be missing it. Ants are living/surviving in water by LIVING LIGHTLY on the surface of their supporting material; they are living SUSTAINABLY on their supporting material. THEY ARE NOT STRESSING their supporting material beyond what it can handle to support ant life.
The few humans who are doing this, showing the way, are in ecovillages, notable Findhorn in Scotland and in a world ecovillage summit in Portugal summer of 2011: ecovillagenews.org
J-n
not rated yet May 02, 2011
What if you want to drown the ants? Just add soap to the water, which greatly reduces its surface tension of water and sinks the raft, said Mlot. "With soap, the ants will drown within a matter of seconds, whereas they can survive for days or even weeks on the raft otherwise."


Medical Intuitive -- Did you miss this part of the article?
Javinator
not rated yet May 02, 2011
Medical, that is not a good metaphor.

Also, I (and likely others) imagine that every chunk of text you have CAPITALIZED is being SHOUTED LOUDLY.
Paljor
not rated yet May 03, 2011
First all of this shouting is giving me a headache. second if you just left particles in a way in which they would form new ones eventually through random chance something would happen. imagine the complex molocules of life being the odds of getting a perfect row of cards (correctly suited) from a randomly shuffled hand. (yes i know the odds are a lot slimmer) eventually through countless reshuffling you would get a perfect line of cards (correctly suited)
TheGhostofOtto1923
3.9 / 5 (14) May 03, 2011
So a million years of chemistry and then a frozen iceball for billions of years is how life got started, that's what you're telling us?
Funny. I reviewed my prior comments and it seems I was only suggesting that life could have spread in comets the way fire ants or spore-producing organisms spread. The links I posted definitely refute MMs uninformed incredulity at this.

So apparently his Putzness has confused panspermia with abiogenesis in a panic to win at any cost. Of course I blame religion for ruining MMs ability to reason fairly and accept defeat gracefully. Moses never gave up did he?