THE ants may go marching one by one, but they end up forming a superstructure of thousands — and together they can form a raft that stretches the boundaries of the laws of physics, according to new research released today. Ants have exoskeletons that are naturally hydrophobic, or water repellant. A single ant can walk on water because of the buoyancy of the air bubbles trapped next to its body, and the water’s own surface tension. However, when thousands of ants stand on top of each other, their multiplied weight should cause them to sink. But for years, biologists have observed fire ant colonies floating down flood plains and rivers in their native South America.
For the first time, a group of engineers has attacked the question of ant flotation from a physics perspective. Ants float as a group because they can harness the power of nearby air bubbles. Grasping each other’s mandibles or front legs with a force 400 times their body weight, the ants are able to trap small pockets of air between them — like a group floatation device.
