Most of us have only seen fire ants where they are outside of their mounds, swarming around the ground looking for something to eat, but it's actually the way the insects move underground that scientists at Georgia Institute of Technology have been studying. They think the way that fire ants move through sand could inspire more effective search-and-rescue robots that would help save human lives.
"Lots of the materials in disaster sites — landslides, rubble piles — are loose materials, which you're going to potentially have to create structures out of," lead researcher Nick Gravish told the BBC this week. "You might want, for example, to create a temporary structure for people buried down beneath."
Gravish and his fellow researchers built several massive ant farms — like the ones many of us had as kids but of "scientific grade" — so they could watch fire ants move through their tunnels. They used special high-speed cameras and X-ray tomography to examine how the ants — which often need to evacuate their nests quickly in case of flooding — travelled through the loose, sandy soil. They jostled the ant farms to make the insects fall and then watched how they righted themselves and continued their journeys. Gravish said it wasn't easy to travel through the sand tunnels, as the ants made constant "slips and falls," but they did move quickly. They did all that despite the challenges of moving through tight, crowded spaces with limited visual sensory input and very limited ranges of motion.
"We were so surprised to see them move so fast," Gravish told Discovery News. "You get a sense that slipping and falling is not a problem. We see that ants can run over the top of each other, and lift each other up. They can scramble as fast as possible and there's no penalty for that."
One of the major revelations of the research was that the fire ants didn't rely solely upon their legs for movement. They also used their antennae as additional limbs to help maintain their balance when they started to fall. The behavior has not previously been documented to this extent and could be useful in building locomotion systems for future robots.
The research also revealed how the ants actually built their tunnels, keeping them to one body length in diameter so they would always be close enough to tunnel walls to right themselves if they started to slip or fall.
"We're very interested in how the next generation of robotics, which is going to be at the millimeter scale, will move through torturous complex environments," Gravish told Discovery.
The research into fire ant locomotion was published May 20 in the Proceedings of the National Academy of Sciences.
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