The Science of Underground Kingdoms
upstart writes:
The Science of Underground Kingdoms:
Next, Andrade's team set about analyzing what the ants were actually doing as they worked, and a few patterns emerged. For one, Andrade says, the ants tried to be efficient as possible. That meant they dug their tunnels along the inside edges of the cups, because the cup itself would act as part of their tunnels' structures, resulting in less work for them. They also dug their tunnels as straight as possible.
"That makes sense because a straight line is the shortest path between two points," Andrade says. "And with them taking advantage of the sides of the container, it shows that the ants are very efficient at what they do."
The ants also dug their tunnels as steeply as they possibly could, right up to what's known as the angle of repose. That angle represents the steepest angle that a granular material-a material made of individual grains-can be piled up before it collapses.
To understand the angle of repose, picture a child building a sand castle at the beach. If the child uses dry sand, every scoop of sand they add will slide down the sides of the pile they've already made. More sand will make the pile taller, but also wider, and it will never get steeper. On the other hand, if the child uses wet sand, they will be able to pile the sand steeply enough to build walls, and towers, and all the other things a sand castle might have. Wet sand has a higher angle of repose than dry sand, and every granular material has an angle that is unique to it. The ants, Andrade says, can tell how steep that angle is for whatever they're digging in, and they don't exceed it. That, too, makes sense, he says.
"If I'm a digger, and I'm going to survive, my digging technique is going to align with the laws of physics, otherwise my tunnels are going to collapse and I'm going to die," he says.
Citation: "Unearthing real time 3D ant tunneling mechanics," appears in the August 23 issue of the journal Proceedings of the National Academy of Sciences.
DOI: https://doi.org/10.22002/D1.1996
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