In an apparent display of cooperation and acrobatic prowess, fire ants are able to build Eiffel Tower-like structures whenever they run into a tall wall while they look for food or search for an escape.

Researchers from Georgia Institute of Technology observed this astounding phenomenon, discovering that the ants build the towers without a leader or coordinated efforts. The ant species wanders about adhering to a set of rules, largely unaware of their participation in constructing inches-tall towers of their own bodies.

How Fire Ants Build Towers

"If you watched ants for 30 seconds, you could have no idea that something miraculous would be created in 20 minutes. With no planning, and using trial-and-error, they create a bell-shaped structure that helps them survive," said study lead author and mechanical engineering professor David Hu in a statement.

The team set up a camera to study the ants, accidentally leaving it rolling for one hour after the ant tower was built. What they thought was a merely static capture turned out to be useful: watching the footage at 10 times regular speed showed that the middle of the tower slowly sank.

“When you speed it up, the ants on the surface are a blur and underneath the blur you can see the slow sinking movement of the tower,” explained co-lead author Craig Tovey.

The researchers realized that the sinking, shown by X-ray videography, was the result of bottom ants moving outward under the weight of top ants. Those on the outside, meanwhile, continually rebuilt the tower through moving upward.

The new study is a follow-up to their 2014 research on ant rafts, where they found that simple behavioral rules led to the tower’s creation despite no one taking charge. Each ant searched for an empty spot just like in a parking lot, and stops and allowed more ants to climb on top once she found her place.

The ants were found to withstand 750 times their body weight without injury during the process, and appeared comfortable supporting three ants on their backs at a time. Just like human skin, the ant tower constantly rebuilt and replaced the surface.

Potential Applications

This intimate understanding of how ants build their towers could be applied in robotics. During search-and-rescue operations, small robots could be deployed as they fit through tiny gaps, and they could work together to withstand barriers.

Bio-inspired design, Tovey added, could make human processes become as efficient as the workings of fire ants.

The findings were detailed July 11 in the journal Royal Society Open Science.

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