Humans have long sought to walk on water—a feat associated with the divine, a metaphor for conquering one’s fears. Our attempts to do so have relied on portable flotation devices, but other animals, large and small, have evolved a natural ability to walk on water. For large creatures, the feat requires considerable power and skill, substantially more than we humans can muster. For small creatures, the topic of this Quick Study, it is a subtle art that relies on multiscale processes ranging from the creature-scale motion of the driving leg to the submicron-scale dynamics of the leg’s interaction with the water surface. As such, it is a rich interdisciplinary subject that engages biologists, fluid mechanicians, and materials scientists.
Animals move by applying a force to their environment; the equal and opposite reaction force propels them forward. Terrestrial creatures apply forces to solid ground, generating a propulsive reaction force known as...
