Nature Invented Inter-meshing Gears On Legs of Insects

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Nature, wonderful inventor that it is, developed inter-meshing gears long before man did. The teeny-tiny planthopper  is the creature who ended up benefiting from this genetic twist of fate. Though it’s almost as small as a flea, this insect has a very fast jump, accelerating up to 200 Gs. That is a G force near the level of the highest level a human has ever survived.

The gears with the inter-meshing teeth occur on the planthopper’s back legs, and they enable the insect to accomplish their super-fast, super-powerful jumps, according to a recently published study on these amazing creatures in the journal Science.

To film the bugs as they were jumping, University of Cambridge researchers Malcolm Burrows (a neurobiologist) and Gregory Sutton (an engineer) used a high-speed camera that they rigged up to a microscope.

By examining them closely when they put the planthoppers on their back onto wax that was sticky, the two researchers involved the study noticed that they had small toothed gears on their back legs where they join up to their bodies. The gears mesh and rotate and allow the planthoppers to time the release of their jumps perfectly.

According to the study’s author, Burrows,the specialized gears allow the insects to jump both faster and for longer distances than other insects lacking such gears can jump.  1.13723_SCIENCE_burrows5HR

The inter-meshing teeth on the gears the researchers discovered on the planthopper’s back legs help it in escaping from any potential predators that would like to make a snack out of it. The extra speed and distance gained could be what separates the quick from the dead.

Like the string of a bow pulled taut, the hind legs of the insect are cocked, and when their energy is released during a jump, the insects take of like arrows shot from bows.

According to Burrows:

You suddenly let go, and the arrow goes much faster than if you were to throw it directly.”

The 10 teeth of each of the gears are located on strips at the bases of the insects’ rear pair of legs.

Strangely enough, the inter-meshing gears only exist during the nymphal stage of the planthopper’s life cycle. When they become adults, the gears are molted off. Then, they use friction that is generated from the rubbing together of two parts of their legs to help assist their jumps.

Though structures that resemble gears have been seen on animals such as the spiny turtle, they are only for ornamental purposes.

A biologist from Harvey Mudd College, who did not take part in the study, Anna N. Ahn, enthuses that the new discovery of inter-meshing gear teeth on the hind legs of the planthoppers is “fantastic.”

Burrows theorizes that the “teeth” could have evolved from small bumps that eventually grew larger over time, until they came to resemble the inter-meshing teeth of gears.

The juvenile planthopper is fairly common. It is found in gardens and fields throughout Europe.

According to the study’s co-author, Sutton, who now is employed at the University of Bristol, unlike gears in machines that humans design, the one on the hind legs of the planthoppers “are evolved,” and they represent “high speed and precision machinery evolved for synchronization in the animal world.”

Written by: Douglas Cobb

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