Why does a single fire ant Solenopsis invicta struggle in water, whereas a group can float effortlessly for days? By using time-lapse photography to investigate how fire ants S. invicta link their bodies together to build waterproof rafts- a selfassembled hydrophobic surface.The ants can considerably enhance their water repellency by linking their bodies together, a process analogous to the weaving of a waterproof fabric.
Overlooking its diminutive size and shortcomings in soapy solutions, the ant raft has attractive traits with respect to manmade flotation devices. It simultaneously provides cohesion, buoyancy, and water repellency to its passengers. It can be constructed quickly (in approximately 100 s) without any additional equipment. It can accommodate thousands to millions of passengers with zero casualties. But perhaps most strikingly, the ant raft is self-assembling.
Many of these benefits are due to the ant’s small size. At the scale of millimeters, ants have great strength, high speed, and the ability to trap air pockets when submerged, which in turn makes their rafts water repellent. These abilities will likely vanish at large sizes. Roboticists interested in building biomimetic ant rafts will need to design robots that can both reversibly attach to and traverse over one another. Moreover, they will need to understand which processes of raft assembly process are coordinated as opposed to stochastic.
Self-assembly and self-healing are hallmarks of living organisms.The ant raft demonstrates both these abilities, providing another example that an ant colony behaves like a superorganism.
(A) An individual ant’s exoskeleton is moderately hydrophobic. (B) Enhanced water repellency of a raft of ants. (C) Buoyancy and elasticity of the ant raft. (D) The plastron air bubble of an ant in soap-free water. (E) An air pocket trapped in a submerged ant raft.
Information Source: https://www.pnas.org/content/pnas/108/19/7669.full.pdf
