Now you can add bridge building to the remarkable abilities of the unstoppable ant army. Researchers at the University of Sydney, Australia, have captured a time-lapse video of ants using their own bodies to build a bridge.
The army ants use their bridges to span gaps in the forest floor as they forage for food, says the newly published paper detailing the process. They don’t just bridge the gap, either. The ants continuously vary the length, width, and even the position of the bridge depending on traffic rate and the surrounding environment.
“After starting at intersections between twigs or lianas travelled by the ants, the bridges slowly move away from their starting point,” co-author Dr Christopher Reid told Sydney University News, “creating shortcuts and progressively lengthening by addition of new workers, before stopping, suspended in mid-air.”
The researchers performed field experiment to examine the method behind these structures, and found that the bridges are adjusted “in response to a cost–benefit trade-off.” The cost is ant bodies–more are needed to make bigger bridges–and the benefit is that the whole army can take a shortcut. And these often are just shortcuts. The ants use bridges to avoid walking around the edge of a hole, not just to cross an otherwise-impassable crevasse.
The team, at the University of Sydney’s Insect Behavior and Ecology Lab, found that often the ants stopped moving their bridges before they’d reached the shortest possible route, suggesting that they are balancing the need to keep ants foraging with the need to create better shortcuts.
One possible outcome of this research would be to control robot swarms, letting them reorganize themselves autonomously as they slowly advance on the helpless humans that foolishly built them. Or, more likely, to operate in disaster areas where humans may not have safe access.
“Such swarms could accomplish remarkable tasks, such as creating bridges to navigate complex terrain, plugs to repair structural breaches, or supports to stabilize a failing structure,” says Reid.