The Issus Bug’s “Mechanical” Gears

Well Wonderguests, Nature has done it again! Humans with microscopes have recently discovered the use of organic moving gears on a life form. This find proves that, while humans are a resourceful bunch, the natural process of evolution has accomplished a great deal more than we previously thought. In this instance a clock-like mechanism was first created by a creature other than humans.

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To find these mechanical gears we have to take a close – very close- look at the Issus insect. This little bugger is most common in Europe and the surrounding area. It spends a lot of time living off of the precious phloem sap from plants like the European climbing Ivy. Generally speaking, the Issus are considered to be nondescript and rather uninteresting but, if you look closely, you’ll find a whole lot more than you expected. Specifically the use of mechanical gears. If you expect to find these gears on just any of the Issus insects you’ll be sorely disappointed.

The Issus nymphs, or insect “children,” use the gears in a similar sort of way that people use training wheels to ride bikes. At a certain point they no longer need them for balance. From the published abstract in Science magazine:

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.

These gears encourage proper jumping from the adolescent Issus bug. Without the organic apparatus, the nymphs would rotate uncontrollably along their y-axis (see Yaw Rotation). This would cause the Issus younglings to land facing a different direction.

The strangest part is how effective the gears are! From the University of Cambridge website:

The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box. Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to man-made gears such as bike gears – essentially a shock-absorbing mechanism to stop teeth from shearing off.

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To get a better idea of exactly how these gears work, check out this video! It truly is amazing that such a mechanism can exist in an organic setting.