During the lockdown of 2020, Dr Victor Ortega Jiménez watched as tiny insect-like creatures performed acrobatics in a creek near his home. He observed these tiny arthropods jump up to ten centimetres high, perform a flip in the air, and land smoothly on the surface of the water, all within the blink of an eye. What were these animals? Springtails.
Springtails are tiny, semi-aquatic invertebrates that live in creeks, marshes and ponds. These flea-like creatures are “as small as a grain of sand“, and capable of jumping over 10 times their own height at a speed faster than any wingless organism previously recorded. This leaping motion was thought to be random and uncontrolled, but researchers at the Georgia Institute of Technology and Ajou University in South Korea have discovered that the hopping of the springtail is a precise skill which requires control of the take-off, mid-air spinning, and landing.
Springtails have a tail-like organ on their underside called a furcula, which they use to propel themselves off the water’s surface. When this occurs, the collophore, a tube-like structure which can hold and adhere to water, takes up a droplet of water. As the springtails launch themselves into the air, they curve into a U-shape, generating a force which causes their bodies to rotate to the right side up. The creatures then land on the water’s surface, gliding on their hydrophilic collophores which adhere to the liquid below to ensure a stable landing. All of this happens within 20 milliseconds.
Dr Ortega Jiménez and his team used mathematical modelling and fluid dynamic experiments to work out the mechanism behind the springtails leaping motion and, alongside the researchers at Ajou University, built tiny robots that imitate the movement. These robotic imitators can stick their landing 75% of the time, compared to the real springtails 85%.
These tiny creatures, and their robot siblings, could lead to huge advances in the fields of robotics and aerodynamics, allowing robots which can explore new terrains. Not bad for a tiny almost-flea.