The little jumping bug Issus coleoptratus uses "toothed gears" in its joints to precisely synchronize its hind legs as it leaps forward.
It is the first case of "mechanical gears" found in nature.
Only case
This fulgoromorph is the first animal that we know that has structures in the body that work like gears, which synchronize the propulsion impulse of the hind legs.
However, this ability is quickly lost : as I. coleoptratus transitions from nymph to adult state, these gears disappear.
Insects of the genus Issus, commonly called ‘grasshoppers’, are found throughout Europe and North Africa. The discoverers of these gears used electron microscopes and high-speed video capture to discover the existence of the gear and also to discover its exact function.
The reason for the gear, they say, is coordination: To jump, both the insect’s hind legs must push forward at the same time. Because they both swing sideways, if one were to reach out a fraction of a second before the other, it would push the insect off course to the right or left, instead of jumping forward.
The gears are located on top of the insects’ hind legs (in segments known as the trochanter) and include 10 to 12 conical teeth, each about 80 micrometers wide (or 80 millionths of a meter).
In all the cases studied, the same number of teeth was present on each hind leg, and the gears were perfectly attached. The teeth even have rounded curves at the base, a design built into man-made mechanical gears because it reduces wear over time .