Urine Catapulting: This Tiny Bug’s Energy-Saving Strategy


| LAST UPDATE 03/04/2023

By Stanley Wickens
sharpshooter insect weird features
Instagram via @cicadagobrr

In a world where we're always looking for ways to save energy, it seems like the tiny glassy-winged sharpshooter insect is ahead of the game. Not only does this little critter pee at an impressive velocity, but it can also fling its urine at speeds of up to 30 centimeters per second! How's that for efficient expulsion?

Scientists have discovered that the sharpshooter's unique peeing behavior is a result of smart engineering and physics innovations. Using a stylus appendage that acts as a catapult, these insects are able to propel their droplets of pee at more than 40Gs - ten times faster than top-end sports cars. But why have sharpshooters evolved in this way? It turns out that their energy-efficient method allows them to expel relatively large amounts of fluid more easily. With xylem sap containing just 95% water and few nutrients, sharpshooters need to drink huge volumes of it - up to 300 times their body weight each day - to get enough energy to survive. And since they're small in size, they need a less demanding method of expulsion.

glassy-winged sharpshooter insect research
Instagram via @lanaturalezadelori
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But there's more: scientists also think that the way sharpshooters fling their pee could help them escape detection from predators. By throwing droplets large distances, they may be able to mask chemical cues in urine and avoid being eaten. The study's lead author, Saad Bhamla from Georgia Institute of Technology in the US, says that "little is known about the fluid dynamics of excretion" despite its impact on animals' morphology, energetics, and behavior. That's why he and his team wanted to investigate whether these insects had come up with any clever engineering or physics innovations in order to pee this way. It turns out they had - by evolving a spring-and-lever-like catapult using tools that they use repeatedly at high accelerations. The final question was why evolution led them down this path; through analysis of morphology, hindgut and fluid dynamics within xylem sap itself, the researchers believe this energy-efficient method lets Sharpshooters expel relatively large amounts of fluid more easily.

Who knew that such tiny creatures could teach us so much about efficiency? Perhaps one day, we'll even be able to apply what we've learned from Sharpshooters' super propulsion technique when designing low-power gadgets like smartwatches. As Elio Challita from Georgia Institute of Technology puts it: "This work reinforces the idea of curiosity-driven science being valuable."

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