Toothed gears observed in living organism for first time

Nature : In order to perfectly synchronize their hop, insects of the species Issus coleoptratus have developed a jumping mechanism that involves rounded joints with cog teeth analogous to the gears in rotating machinery. The joints intermesh and rotate in unison so that the insect’s two hind legs move at the same angular velocity. Cambridge University’s Malcolm Burrows and Gregory Sutton, whose paper appeared today in Science, say this may be the first example of rotary motion with toothed gears to be observed in nature. Interestingly, the mechanism has only been observed in nymphs, not adults. When a nymph sheds its exoskeleton for the last time before reaching adulthood, the gears disappear. The researchers have proposed various reasons, including that the mechanism could be subject to breaking and is only repairable in the young and that the frictional-contact method observed in the adults simply works better for older animals.