Sharpshooter insects excrete vast amounts of urine using an anal catapult

Snipers produce 300 times their body weight in liquid waste each day, saving energy through a phenomenon called hyperpropulsion.

To Christa Leste-Laser

Small sniper insects produce so much urine that instead of shedding it, they expel it from their bodies as energy-efficient, high-velocity droplets.

These insects are forced to eat small amounts of nutrients in large amounts of water and excrete 300 times their body weight in liquid waste each day. By twisting part of the anus to release a drop of urine and then spring-loading the urine out, waste can be expelled for a fraction of the energy cost of creating a stream, says the Georgia Institute of Technology in Atlanta. He said Saad Bhamla.

A species of leafhopper, only a few millimeters long, the sniper feeds on the sap in the xylem tubes that extend from the roots to the leaves of the plant. Composed of 95% water and 5% minerals and other nutrients, xylem sap is naturally sucked into the interior of plants, making it difficult for insects to pump. This means the insects are already working hard to return very little of the energy-providing nutrients, he says, Bhamla.

He and his colleagues wondered how tiny insects could afford to expend the additional energy needed to urinate.

“If you were only drinking diet lemonade and that was your entire diet, you wouldn’t want to waste energy on any part of the biological process,” he says. It’s how small creatures should be.”

To understand their secret, the team analyzed 22 waste emissions from five glassy-winged snipers (Homalogiska vitripenis). In particular, we observed the movement of a pointed, hairy appendage called an anal stylus as it rotated open to squeeze out droplets. Each droplet grew for about 80 ms, after which the stylus was rotated slightly to create spring loading.

At that point, the stylus was twisted quickly, sending droplets into the air. Amazingly, the droplets moved 40 percent faster than when he pressed the stylus, says Bhamla.

This mechanical phenomenon, in which droplets move up and down faster than the rotating surface that ejects them, is known as “super-propulsion”. It’s rare in engineered designs and has never been detected in vivo, says Bhamla.

Through physical and mathematical modeling, the team found that the sniper stylus transfers energy to wastewater droplets very efficiently. The system’s success depends entirely on timing, he says, Bhamla. Just like a high diver jumping off a diving board.

Because the droplets are soft and easily deformed, they can store energy, increasing their speed while propelling them through the air. As a result, snipers use an estimated 4 to 8 times less energy to dislodge waste than to generate jet streams, which require considerable energy to produce ejection velocity. “All our models suggest that he is one of the most energy efficient pathways to repel droplets,” says Bhamla.

Larger animals and humans don’t need such energy efficient urination systems.Because the cost of creating a stream of urine is negligible compared to their energy intake, muscle strength and urine output. [as a sharpshooter] It’s very difficult,” says Bhamla.

The discovery could inspire the engineering design of energy-efficient self-cleaning systems for smart wearable electronics, anti-fogging systems for goggles and eyeglasses, or transportation systems for soft robotics, he says.

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