An international group of German and American scientists has found that Army Ants can create complex bridges in Central America’s rainforest floor. The lead author, Dr. Christopher Reid of the New Jersey Institute of Technology’s Department of Biological Sciences with colleagues from Princeton University and George Washington University as well as Harvard University and the Max Planck Institute for Ornithology and the University of Konstanz wrote about the study in the scientific journal Proceedings of the National Academy of Sciences. Nomadic species, ants move their colonies throughout the rainforest on a daily basis. It can be very difficult to move up to one million people on an uneven forest floor. A team of army ants creates a “living bridge”. (Image: movie-usa.glencoesoftware.com) In this study, the authors said they observed several of the ant workers using their own bodies to plug holes the colony was travelling through. The ‘living bridges’ were created by army ants. In some cases, workers attached themselves to one another to make living bridges. They were capable of constructing and disassembling living bridges in a matter of seconds. This allowed the colony members to move at great speeds over new terrain, which was often unknown or unpredicted. Dr. Reid stated that the bridges are dynamically affected by the flow of traffic on the trail. Think about how the George Washington Bridge, New York City-New Jersey, would change its position depending on traffic. The ants wanted to find the shortest possible route. Dr. Reid was shocked by this stoppage and said that it was surprising for them. Although the bridge could have moved faster to make better shortcuts in many instances, the authors found that the ants were unable to keep the bridge open. They also had to stop workers from being used for vital tasks like brood transport and prey capture. The army ants made a decision to make this trade-off when building their bridges. They could not construct longer bridges without causing a shortage of workers. Reid stated that ants’ system could be used by swarms of robotics. He said, “Our work can have implications for other self-assembling technologies such as reconfigurable material and autonomous robot swarms.” A network of independent robots would create large-scale structures using the same principles of the army ants. The robot swarm could perform remarkable tasks such as building bridges that can navigate difficult terrain or plugging structural cracks. They also have the ability to support structures in distress. This system could help robots perform better in unpredictable and complex settings, where humans are not present. Citation: “Army Ants dynamically adjust living Bridges to respond to a Cost-benefit Trade-off,” Chris R. Reid and Matthew J. Lutz. Simon Garnier. Proceedings of the National Academy of Sciences. Publication online prior to print November 23, 2015. DOI: 10.1073/pnas.1512241112. Video: Army Ants make a living bridge
