TAMPA, FLORIDA—The rapid acceleration of a cheetah chasing down its prey is slow motion compared with the pee flying out of the rear end of a glassy sharpshooter. A new study has found this centimeter-long, plant-sucking insect has specialized structures to accelerate the removal of waste at 200 meters per second squared, an order of magnitude faster than a cheetah can get up to speed. More than just an excretory curiosity, the sharpshooter’s behavior could one day help engineers design new kinds of printers and other devices that move tiny amounts of fluids around.
The sharpshooter has an unquenchable thirst. It taps into the water-conducting tissue of a variety of plants, from which it needs to suck up as much as 300 times its weight in liquid a day to get enough nutrients to survive. All that liquid has to go somewhere, and the droplets flung from these insects’ rear ends rain down from infested trees.
Splattered one day by leafhopper showers, one biophysicist decided to take a close look at the sharpshooter’s rainmaking machinery. High-speed videos revealed each droplet accumulates on a pointy tip at the far end of the sharpshooter’s anus, which has a joint that catapults the water away, he and colleagues report here today at the annual meeting of the Society for Integrative and Comparative Biology.
When the researchers looked closely at this tip using x-ray tomography and micro–computerized tomography scans, they realized it has two projecting hairs, which flick the water as it’s ejected. That greatly speeds the droplet’s departure, they report. That’s not surprising, as insects tend to fling their excrement as far away as possible to avoid attracting predators. The hairs are kept poised for action by means of a tiny latch, and they are activated by a spring that releases to flick the water away. Both structures are very hard to pinpoint in living organisms.
The researchers hope their findings will improve the booming field of microfluidics, in which tiny amounts of fluids are manipulated to diagnose disease, sequence DNA, and study cells one at a time to learn about their DNA and proteins. And because the insect can infect its host with disease-causing bacteria, a better understanding of its biology could be crucial to plant scientists and farmers. The team is already taking the first step—recreating the sharpshooter’s rear end by attaching false eyelashes to a motor.