Living creatures adapt to their environment in all kinds of ways, in order to survive. Some camouflage themselves to blend in, while others learn to live off arsenic substances. The biggest hazard to survival for the South American red ants is the constant flooding - So they get around it, by holding onto each other, and floating away on their 'living' rafts.
What's even more amazing is the pace at which they do it - Apparently at the slightest inkling of a flood, the entire ant colony gathers its eggs and makes their way to a pre-made underground network of tunnels. As soon as the waters start to rise above the ground, they hold on to each other and form a floating structure. This entire endeavor takes less than two minutes. If needed, the fire ants can float around like this for months on end.
While the survival technique has been well documented, nobody had ever figured out the mechanics of how they stay afloat, until recently. Intrigued by the many tales they had heard Georgia Institute of Technology engineering professor David Hu, graduate student Nathan J. Mlot and systems-engineering professor Craig Tovey decided to investigate how these virtually indestructible insects perform this neat trick, by conducting a number of experiments.
They began by throwing a clump of them into the water to test what would happen. The insects immediately spread out into a pancake-shaped raft by gripping onto each other's legs with claws or jaws and forming an interweaving pattern that resembled a waterproof fabric. What was interesting was that even the ones at the bottom, were buoyant, thanks to the thin layer of air trapped amongst the tiny hair on their bodies.
The scientists than tried to create a hole in the raft, by taking a couple of ants away from the bottom - To their astonishment, two of the passengers immediately scuttled over to take their place making them realize that the ants could somehow sense the exact density they needed to keep floating. Even poking the raft with a twig to make it sink did not deter these smart insects - They simply contracted their muscles, which helped trap air better and prevent them from drowning.
The only way they could prevent the raft from happening was by adding a film of soap to the water. That's because soap reduces the surface tension of the water, which in turn makes the ants less buoyant. It is no wonder that these pesky creatures are virtually indestructible.
Another cool experiment the researchers tried was placing the ants inside a dry beaker and swirling it around - The ants once again realized the power of being united and clumped themselves into a ball, tight enough to be picked up by a pair of tweezers.
The scientists also concluded that the optimal size for a 'living raft' was 100 ants and that while they seem to work better if they are from the same colony, a mixture from different colonies works fine too. The conclusion? - It's all about being united!
The researchers hope that their findings will be useful for designing boats that can self-repair and also help engineers develop more-effective waterproof materials.
Resources: NationalGeographic.com,dailymail.co.uk, sciencemag.org