Insect With Built-In Mechanical Gears


Wed, Sep 18th, 2013 12:00 by capnasty NEWS

On the Smithsonian, a fascinating look at the small hopping insect Issus coleoptratus, the only animal to use toothed gears "to precisely synchronize the kicks of its hind legs as it jumps forward." The above image, which has been magnified with an electron microscope, is credit to Emeritus Professor Malcom Burrows at the Department of Zoology of the University of Cambridge.

The main mystery is the fact that adults of the same insect species don’t have any gearing—as the juveniles grow up and their skin molts away, they fail to regrow these gear teeth, and the adult legs are synchronized by an alternate mechanism (a series of protrusions extend from both hind legs, and push the other leg into action).

Burrows and Sutton hypothesize that this could be explained by the fragility of the gearing: if one tooth breaks, it limits the effectiveness of the design. This isn’t such a big problem for the juveniles, who repeatedly molt and grow new gears before adulthood, but for the mature Issus, replacing the teeth would be impossible—hence the alternate arrangement.

There have been gear-like structures previously found on other animals (like the spiny turtle or the wheel bug), but they’re purely ornamental. This seems to be the first natural design that mechanically functions like our geared systems.



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