27 March 2011

Rotary locomotion by a tiger beetle larva


The coastal tiger beetle (Cicindela dorsalis media) lives on the beaches of Cumberland Island off the coast of Georgia.
Tiger beetles are among the fastest of insect runners, but their larvae are slow and worm-like. If they’re exposed and threatened, running isn’t an option. Instead, they turn themselves into living wheels. They leap into the air, coil their bodies into a loop, and hit the ground spinning. The wind carries them to safety...

If you touch it on its bottom half, it arches its body backwards head-to-tail, forming a loop. It then violently uncoils, launching itself off the sand and coiling in the other direction. When it hits the again, its momentum carries it forward... They move at around one mile per hour, spinning at 20 to 30 revs per second, and travelling for up to 25 metres.
More details, a diagram of the motion, and and several additional videos at Not Exactly Rocket Science, including this one -

- of salamanders and caterpillars capable of rotary movement. There is also a spider video, but old-timers at this blog will remember a better one two years ago showcasing the Saharan rolling spider.

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