Fire Ants Build Sinking Eiffel Towers When Trying to Escape

Posted on July 12, 2017

Scientists have observed fire ants building vertical structures in an effort to escape. The ant towers resemble the Eiffel tower. They enable the fire ants to move vertically without harming any members of the ant colony. Researchers at the Georgia Institute of Technology observed ants building the towers in a recent study.

David Hu, a professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering and co-author of the study, says in a statement, "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."

The study builds on the group's ant raft research from 2014. The ants follow a certain set of rules when building the towers. Each ant looks for an empty spot like a car trying to find a space in a crowding parking lot. Once an individual fire ant finds an empty space (typically at the top of the tower) it stops and braces itself enabling more ants to climb over it. The tower grows wider as it grows vertically to support the structure. The ever-widening base enables the ants to better distribute their weight. The tower is also in constant motion and the column sinks as the insects work. The sinking was confirmed using X-ray videography.

The Verge reports that the fire ants appear to follow these three rules when building a tower:

Craig Tovey, a co-author of the study and professor in the Stewart School of Industrial & Systems Engineering, says, "We found that ants can withstand 750 times their body weight without injury, but they seem to be most comfortable supporting three ants on their backs."

A research paper on the study was published here in the journal, Royal Society Open Science. Here's a video of ants building a bell-shaped tower.

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