Zoologger: Transformer insect has gears in its legs

[Nipuna]

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FOR a disconcerting experience, consider how mechanical you are: joints, valves and a whole lot of plumbing. Impressive, but not as impressive as the insect whose larvae have interlocking gears.

Issus coleoptratus is a type of plant hopper – a bugs that is known for its prodigious jumping. It takes off in just 2 milliseconds, and moves at 3.9 metres per second.

Malcolm Burrows of the University of Cambridge first ran into the larvae poking around a colleague's garden, and noticed that each one had meshing gears connecting its two hind legs (see photo). High-resolution microscopy and high-speed photography showed that the top of each hind leg has 10 to 12 teeth, each between 15 and 30 micrometres long (Science, doi.org/ntc).

The biological cogs mean the legs interlock and move in unison. Burrows suspect they evolved to synchronise the hind legs better and faster than neurons. Videos showed the legs moved within 30 microseconds of each other during a jump.

Adult plant hoppers lose their gears, but still jump well: they rely on friction between the tops of the legs. The reason might be, simply, that gears are easily broken, and as soon as one tooth is sheared off, the mechanism doesn't work as well.

This article appeared in print under the headline "Transformer bug has gears in legs"