This insect's 'pee droplets' accelerate faster than a cheetah

Transcript

Researchers have measured the speed of a sharpshooter's "pee droplets," after the insect uses a mechanism similar to a catapult to send them flying.

Saad Bhamla says the peak acceleration speed of the droplets is faster than a cheetah, or Usain Bolt. 

"When you watch it in real time, you barely can see anything. So we were just trying to figure out what was going on," said Bhamla, an assistant professor at Georgia Tech's School of Chemical and Biomolecular Engineering, told As It Happens host Carol Off.  

There are instances where these insects, nicknamed the "pissing fly," have left passersby wondering if it's raining.

The researchers set up cameras to watch glassy-winged sharpshooters and blue-green sharpshooters and saw that the insects use a mechanism similar to a catapult to fling their waste droplets.  

Sharpshooters are agricultural pests that consume up to 300 times their body weight in fluid per day from plants, according to a video titled "Insect pee: Ultrafast fluidic ejection from sharpshooters," that the team submitted to a conference last month.

Bhamla worked with colleagues at the United States Department of Agriculture (USDA) lab in California, where the insects ability to spread disease has threatened the wine industry.  

Bhamla says the insects have a "droplet ejection mechanism" that works in three phases.  

First, Bhamla explains, an appendage on the insect's back called an anal stylus rotates and opens up. He compares this to a valve that opens up when you turn on a faucet.

That's when the droplet forms.

At this point, "you noticeably see a spring loading mechanism where the anal stylus actually pushes down a little bit more just like you would if you had a gun and you were loading the trigger," he said.

Then "off goes the droplet."

"We measured the accelerations of these droplets from these insects and they achieve about 200 m/second sq. in acceleration," said Bhamla.

"If you want me to put that into perspective, cheetahs or Usain Bolt ... the peak accelerations are about 10 m/second sq. So these things are 20 times faster."

Bhamla's team has come up with a mathematical formula for this, which could be helpful in applying this knowledge in a practical way.  

"If I wanted to come up with an easier way to move droplets for say, fuelling a tiny reactor … we now know a clever way that insects do it. So we may be able to, you know, be inspired by that and build a fast moving droplet shooter."

"We use droplets all the time for blood diagnostics, for space stations. We're surrounded by fluid. So there's no dearth of applications where this could be useful in lots of chemical engineering processes."  

In November, As It Happens spoke with another researcher at the Georgia Institute of Technology who was looking into how wombats produced cubed feces.

• AS IT HAPPENS: Scientist figures out how wombats poop cubes

When asked about the fascination with animal waste at the university in Atlanta, Bhamla said, "We're very curious, passionately curious."

"We're willing to explore questions that initially may seem a little bit, perhaps, not as valid … but nonetheless, tell us something about our own self or about the natural world."

Written and produced by Katie Geleff.