Nature: the Engineer

Posted by Science Explored on October 14, 2013

Nature turns out to be as prodigious an engineer as human beings.  The University of Cambridge recently discovered that a European plant-hopping insect called the Issus coleaptratus possesses natural, biological gears not unlike those found in bicycles, transmissions, and automobile differentials.  Adding to the surprise of this discovery, the Issus has been living comfortably in European gardens for decades.  Only ornamental “gears” have been spotted in nature prior to this discovery; those of the Issus, however, play an essential role in the insect’s survival.

Gears
No, this isn't something out of horror movie.  These are the gears - a remarkable feat of "organic engineering" - of a Issus coleaptratus nymph (photo courtesy of The University of Cambridge).

Asymmetrical in design, the Issus’s gears are interlocked but only function in one direction, unlike the gears of an automobile transmission.  Ten to twelve teeth and grooves serve to synchronize the jumping action of the insect’s hind legs.  Whereas mammals, such as a dog, utilize neuromuscular signals to leap across a roadside curb while on a run, the Issus cannot rely on the same technique.  “The precise synchronization would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinary tight coordination required,” explains Professor Malcolm Burrows of the Department of Zoology at Cambridge University.  The gears thus force both legs to “fire” in tandem, preventing the tiny insect from jumping askew and flying out of control.  Thanks to these “biogears” the insect’s legs spring so close in time that their timing is measured in fractions of a second: both legs move within 0.000030 seconds of one another.  Compare that to human reaction time at 0.1 seconds, which is how quickly we can interpret the firing of a gun to begin sprinting down a track.  The insect accelerates so quickly that the amount of force generate on its minuscule body can be measured at upwards of 500 Gs (a sharp curve or loop on a roller coaster hardly generates 2-3 Gs)!

Scientists are still baffled, however, about why only the nymph stage of the Issus possesses these gears.  As the Issus molts into its adult body, the gears seemingly disappear.  Without these gears, the Issus might encounter trouble when it comes to leap frogging between leaves, escaping predators, or even preventing itself from crash landing into the ground below its leafy canopy environment.  Entomologists, or scientists who study insects, theorize that because the Issus, like other insects, stops molting when it reaches adulthood, it cannot repair its gears should they become damaged.  This phenomenon might indicate why the adult insect displays no gears – a gear with a broken tooth becomes ineffective.  Regardless, the adult Issus is still able to perform impressive leaps – how exactly this is done is still a mystery.  On the other hand, there is no mystery when it comes to nature’s status as an excellent engineer.  After years of thinking otherwise when it comes to mechanical gears, it appears that nature beat humanity to the punch!

 

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