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Gears Synchronize Propulsive Leg Movements in a Jumping Insect

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gearcutter

Industrial
May 11, 2005
683
"Gears are found rarely in animals and have never been reported to intermesh and rotate functionally like mechanical gears. We now demonstrate functional gears in the ballistic jumping movements of the flightless planthopper insect Issus. The nymphs, but not adults, have a row of cuticular gear (cog) teeth around the curved medial surfaces of their two hindleg trochantera. The gear teeth on one trochanter engaged with and sequentially moved past those on the other trochanter during the preparatory cocking and the propulsive phases of jumping. Close registration between the gears ensured that both hindlegs moved at the same angular velocities to propel the body without yaw rotation. At the final molt to adulthood, this synchronization mechanism is jettisoned."

Link to the full article -
Issus-02-0913-de.jpg


Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
 
funny I saw this today earlier.

Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
 
gearcutter-

Thanks for the link.

Being a hardcore "gearhead" myself, I'd love to think that these tiny exoskeleton structures on this critter are actually a functional set of gears that resulted from millions of years of biological evolutionary forces. Unfortunately, there is one glaring problem with this theory: Every other form of life (insects, mammals, birds) has evolved to rely on independent control of each appendage (wings, legs, etc) for any movement. Independent control over wings, legs, arms, etc. combined with sensory systems providing equilibrium feedback and the basic mental capacity to control muscle systems in a logical fashion is common to almost every insect, mammal, bird, reptile, etc. If we accept the theory of evolution to be true, then a bug with geared hind legs that only allow it to leap in one direction when attempting to flee would quickly die off. Predators would quickly adapt their behavior to take advantage of this limitation.

The more likely explanation for the structures on this critter's hind legs is that they are simply just a fluke of nature that will likely disappear in a few thousand years. If nature was that brilliant birds would have propellers.
 
tbuelna,

It would be really interesting to model the profile.
Determining if the profiles are in any way conjugate would be the first thing that I'd like to look at.
Note the very low pressure angle and the amount of, what looks to be, relief near the tip and root, with the root area looking 'almost' like it has been undercut.
I may end up purchasing the paper as the authors seem to go into further detail about this.

I agree with your points about the evolution of this mechanism but, keep in mind, that the article points out that this particular mechanism is discarded and eventually replaced with a friction drive once the insect has matured.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
 
"The more likely explanation for the structures on this critter's hind legs is that they are simply just a fluke of nature that will likely disappear in a few thousand years. If nature was that brilliant birds would have propellers."

That is the theory of natural selection. Changes occur due to random mutation, not intelligence. They spread due to increasing the likelihood of survival and procreation.

 
Compositepro said:
That is the theory of natural selection. Changes occur due to random mutation, not intelligence. They spread due to increasing the likelihood of survival and procreation.

I'm not disputing the fundamental logic behind natural selection and biological evolution. Instead I was questioning the conclusions drawn by the researcher as to how and why these particular exoskeleton structures came to exist on this critter. There was no conclusive evidence presented of cause/effect. If what the researcher claims about the origin and function of these "gears" is true then we should see them on other similar insect species, right?
 
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