NewsFlash: Insect Uses Leg Gears to Jump
Think only humans use gears? Think again! Some insects use “gears” to synchronize their legs during jumps.
When humans prepare to jump, the brain synchronizes our legs to initiate uniform motion in the appropriate direction, and to prevent us from spinning. Insects use other methods, and one, the Issus coleoptratus plant hopper, actually employs leg “gears.” When the plant hopper prepares to jump, these gears lock into place to ensure that the insect’s legs push off at the same speed and direction.
Interestingly, the “gears” disappear from plant hoppers that have shed their exoskeleton for the final time and reached adulthood. Instead, the adult insects rely on friction for leg synchronization.
It is not known why adult plant hoppers have no leg “gears.” However, it has been hypothesized that “gears” broken while the insect is young can be repaired by subsequent moltings. If so, broken “gears” may compromise a young insect’s survivability for a limited time, but similar damage in an adult plant hopper would be permanent. It also has been suggested that an adult insect’s body size and rigidity enable frictional synchronization to work more effectively than would be possible before a plant hopper is fully developed.
Can your students form other hypotheses? How might they test these ideas?
For more information about the insect and to view a video by scientist Malcolm Burrows, one of two scientists who discovered the gears, check out the story from the University of Cambridge.