If you don’t like insects, and ants in particular, the video above is going to do nothing to enhance your day. But what it does show is quite incredible. When in water, fire ants band together and create a water-tight floating raft capable of holding a large amount of weight without breaking.
On the one hand this is nature at its coolest with the ants clearly evolving to automatically carry out this survival behavior when necessary. On the other, it’s behavior that could lead to the development of better waterproof materials.
Scientists have been studying these ants for years, but until now have never looked into this raft system they form with their own bodies. A single ant doesn’t do very well in water, but when a group are dropped into liquid they create a raft that no water can break through. Better yet, none of the ants get wet even on the lowest level of the raft.
The trick to this is the use of air molecules trapped in the hairy, rough exterior of each ant. The air gives buoyancy and a barrier from getting wet. When lots of ants hold on to each other using their mandibles, its as if they are floating above the water on this layer of air. In fact, the researchers found they hold together like adhesive with a force 400x their own body weight.
Such a technique for staying dry is known as the Cassie-Baxter law of wetting. It states that as a surface gets rougher it’s harder for water to maintain contact. In this case the ants not only manage to float, they strengthen their grip on each other when pushed underwater and manage to keep the raft intact. You will also notice in the video that the raft remains flexible.
Research into these ant rafts has been carried out by researchers Nathan Mlot, Craig Tovey, and David Hu at the Georgia Institute of Technology. It is hoped that the technique used by fire ants can be applied to groups of robots working together as well as in the development of new waterproof materials (fire ant jackets, anyone?).