Grasshoppers use a biological catapult mechanism in their legs to launch themselves into the air.

Grasshoppers rely on a specialized anatomical structure called the semi-lunar process, which is a hinge-like part of the knee made of elastic cuticle. This mechanism allows the insect to store massive amounts of potential energy that muscles alone could not provide. By using a 'catch' or locking mechanism, the grasshopper can contract its large extensor muscles slowly to build tension without moving the leg.Research conducted by scientists like Dr. Malcolm Burrows at the University of Cambridge has shown that this process is similar to drawing a bow before firing an arrow. When the catch is released, the energy is discharged in as little as 1 millisecond. This rapid release generates a peak power output that far exceeds the maximum power capability of any known animal muscle fiber.The energy density stored in the grasshopper's pleural arch and semi-lunar process is approximately 50 joules per kilogram. This mechanical advantage allows a grasshopper to accelerate at rates reaching 20g, or twenty times the force of gravity. Without this biological spring system, the muscles would simply tear themselves apart trying to generate such explosive force.This evolutionary adaptation is crucial for survival, providing a near-instantaneous escape from predators like birds or rodents. Similar catapult mechanisms have been identified in other insects, such as froghoppers and fleas. However, the grasshopper remains the classic model for studying biomechanical energy storage in the field of entomology.