Bugs Use Mechanical Gears To Help Them Jump

Bugs Use Mechanical Gears To Help Them Jump

By R. L. David Jolly

Have you ever watched a leafhopper or planthopper bug jump?  They jump so fast and so far for such a small insect.   For years, scientists were baffled as to how they were able to jump the way they do.  Even more baffling was the way that both hind legs moved in perfect unison, called synchrony.  If one leg moved just a fraction of a second slower than the other, the bug would go spinning sideways instead of going straight.

Greg Sutton and Malcom Burrows were scientists who set their task to learning just how some insects jump so high, fast and straight.  While working at the University of Cambridge, they began studying the jumping mechanisms of planthoppers, leafhoppers and grasshoppers.

First, they put the insects on their backs and then used a small paint brush to sort of tickle them, causing them their back legs to kick.  However, the action was too fast to see.  They then obtained a high speed camera that filmed at 20,000 frames per second.  At that speed, they calculated that it only takes the insect a couple of milliseconds to kick their legs and jump.

In order to get the action on camera, they had to use very bright lights, which produced too much heat for the insects.  Sutton admitted that he ended up cooking some of the insects with the intensely bright lighting.

Their filming also revealed that the insect could flex and kick faster than the average neuron (nerve cell) can fire.  This is when they also noticed that both back legs were in perfect synchrony with each other, even at the incredibly fast speed.  This led the team of researchers to ask how the insects were able to synchronize both legs so precisely with each other.

Using a planthopper nymph for most of their studies, Sutton decided they needed to examine the anatomy of the insect to see if they could find any clues.  When they placed the insects under a microscope, they noticed a row of tiny bumps on the inside of each of the back legs.  Intensifying the microscope’s power, they discovered the tiny bumps were the same as the sprockets on a gear.  The bases of each leg near the body were so close together that the sprockets or gears on each leg perfectly meshed with those on the opposite leg.  The insect would use the gears to cock the legs, making them ready to jump.  Then the gears were released and the legs kicked in perfect unison and the small bug is off and away in less than the blink of an eye.

This is the first time that gears used to synchronize movement in an animal have been observed.  If any of the gear teeth are broken off, they are replaced with the nymph molts, which happens about 5-6 times before they become adults.  Curiously, they also discovered that the gears are only present during the nymph stage of the planthoppers and then disappeared in the adult insect.  Burrows speculates that this is because the adults don’t molt and form new outer shells like the nymphs do and it could not replace broken gear teeth and their lives would be much shorter.  The adults use a form of friction against the body to synchronize the legs to kick and jump at the same moment.

Neither of the authors ventured any evolutionary explanation for the gears on the legs of the nymphs and it’s probably because there isn’t any evolutionary explanation for it.  No one can argue that gears working in perfect unison with each other to produce precise movements can only be the product of an intelligent designer.  Since we know that man did not create planthoppers, the only possible explanation is that they were designed that way by the Designer and Creator of the earth and all of life, the God of the Bible.  He and He alone is responsible for such a perfect design.

References:

Cole, Adam.  Living Gears Help This Bug Jump, NPR: Science, Sept 13, 2013.

Lee, Jane L.  Insects Use Gears in Hind Legs to Jump, National Geographic: Daily News, Sept. 12, 2013.

Lewis, Tanya.  ‘Planthopper’ Insect Legs Have Interlocking Gears That Help With Hopping (VIDEO), Huffington Post: Science, Sept. 13, 2013.