Would you let your co-workers walk all over you? Army ants do it - fitting their bodies into "potholes" to smooth over rough terrain. It helps keep the colony fed by speeding up the route from nest to prey and back.
Scientists from the University of Bristol say they first noticed the army ants' (Eciton burchellii) unusual behaviour in the insects' native rainforest home in Panama. To investigate this further, the researchers inserted wooden planks, drilled with a variety of different sized holes, into the army ants' trails.
They found that the ants did indeed plug the holes, but the team also discovered that individuals would size-match themselves to a hole for the best fit. The ants range in size from .08 to .4 inches. Biologist Dr. Scott Powell says, "When the ants bump into a hole they cannot cross, they edge their way around it and then spread their legs and wobble back and forth to check their fit. If they are too big, then they carry on and another ant will come along and measure itself in the same way. This carries on until an appropriately sized ant plugs the hole."
At this point, Dr Powell told the BBC News website, the ant becomes a "living surface" remaining in place for hours at a time while thousands of foragers walk back and forth across the trail. At the end of the day, when the traffic eventually diminishes, the ant that forms this motionless plug will detect that and pop out of the hole and run home," Dr Powell said.
The scientists found ant-plugged smoother surfaces speeded up the route from prey to nest and also increased the daily prey intake, which for army ants consists of other species of ants and other bugs.
Co-author Professor Nigel Franks, also from the University of Bristol, added: "I think every road user who has ever inwardly cursed as their vehicle bounced across a pothole - jarring every bone in their body - will identify with this story. When it comes to rapid road repairs, the ants have their own do-it-yourself highways agency."