Vctor Ortega-Jiménez was looking at springtails early in the Pandemic. The organisms are the most abundant non-insect arthropods on the planet, and they are able to jump on the water surface and land in the same spot.
The hypothesis was brought to his lab in Georgia Tech's school of chemical and biomolecular engineering. The researchers were able to see the mechanics of springtail movement for the first time using a combination of computational androbophysical modeling. They were able to figure out how springtails control their jump, self-right in midair, and land on their feet, all within the blink of an eye.
The water surface is a very precarious place for these extraordinary organisms. We need to understand the effects of both aerodynamic and hydrodynamics when they jump from and land on water. The puzzle we set to solve in this paper was how they land on their feet on the water.
The research was published in the Proceedings of the National Academy of Sciences.
Understand springtails.
The researchers found that springtails are successful because of their posture and appendages. They adjust the angle of their jumping organ when they take off. They change their posture midair into a U-shape that creates aerodynamic Torque, which is the fastest of all wingless organisms. The springtail has an appendage that holds water.
Springtails are part of the Collembola family and are known for having a tube-like structure that holds a water droplets. The researchers found that the collophore is necessary for the springtail to glide on the surface of water and land on its feet. The researchers calculated how the springtail takes advantage of its collophore for stable landings using a mathematical model.
"We're showing that the collophore is for their survival, and we've never shown anything like that before," he said. They need this for stability, controlling their takeoff, and how to perfect land.
Springtails were able to control their takeoff angle and speed. They used a mathematical model to figure out how precise the jumps were. If springtails can control the angle of their body, they can glide on the surface of the water, according to the model.
The self-righting ability of springtails was explored by using dead and living springtails in a wind tunnel. The perfect landing was created by the U-shaped posture of the springtails and the droplets collected by the collophore.
The research shows how important controlled motion is for predator escape and survival. Without being able to control their gymnast-like escape response, springs couldn't have become the most abundant non-insect hexapods. This new understanding of how springtails control their jump, spin in midair, and land safely on water could lead to advances in fields from robotics to aerodynamics.
In order to replicate their observations in a physical environment, the researchers built small robots to do so.
The orientation of the robot in the air for landing and jumping has been a challenge. This research could inspire insect-scale jumping robots that are able to land safely and expand their capabilities in new terrains, such as the open-water surfaces in our planet's lakes and oceans.
The researchers created a small robot with drags that they could use to land.
Bhamla said that the native robot spins out of control and lands unpredictably. We show the robot can achieve stability and land on its feet if you add each of these increment.
The results are significant since the robot has a 75% success rate. The results could affect more than just springtails.
We are opening this box of what smaller animals can do. They don't have as much control as big animals because they are small. There are possibilities of control at this small scale that could give insight into the origins of flight in organisms.
More information is available in the Proceedings of the National Academy of Sciences. The DOI is 10.1073/pnas.2211283118.
Journal information: Proceedings of the National Academy of Sciences
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