Fire ants band together into rafts and bridges by each making an average of 14 connections with adjacent ants.

Credit: David L. Hu/Tim Nowack Photography

The insects (Solenopsis invicta) form networks (pictured) to cross streams and deal with floods. To study the networks' structure, David Hu and his team at the Georgia Institute of Technology in Atlanta froze clumps of ants with liquid nitrogen, coated them with vaporized glue and imaged them with a micro-computed-tomography scanner. The team found that the ants grab hold of each other using adhesive pads on their legs. The insects also tend to orient themselves perpendicularly to one another, with smaller ants slotted in between larger ones to maximize the number of connections between them.

The ants could inspire the development of robots and smart materials that assemble into new structures, the authors say.

J. Exp. Biol. 217, 2089–2100 (2014)