Sandfish swim through sand by making waves

摘要

Granular solids such as sand are like fluids in many ways and yet are also quite different. For example, you can pour both sand and water, but piles of sand do not flatten out as a result of gravity, as water does; there are no analogous "water piles". So what about swimming in sand?rnDaniel Goldman of the Georgia Institute of Technology and colleagues have studied the motion of the desert-dwelling sandfish Scincus scincus - a lizard that "swims" as it burrows through sand. High-speed X-ray photography shows that rather than moving its limbs, the creature generates large-amplitude travelling waves on its body to propel it in a truly novel way, which exploits the unique mechanical properties of sand.