How tiny worms leap through the air to catch their prey

Researchers have unraveled the secrets of the predatory worm Steinernema carpocapsae, which has quite a dramatic lifestyle. When the worm sees an insect fly overhead, it folds its body into a loop and launches itself into the air.

Steinernema carpocapsae twirls around wildly, and – if all works well – clings to its target insect using electrostatic attraction.

The worm then crawls inside and releases symbiotic bacteria that kill the host within 48 hours. Feeding on the bacteria and the decaying tissue, it reproduces inside the carcass before releasing new generations into the soil.

Steinernema carpocapsae can jump as much as 25 times its body length. That would be like a human jumping above a 10-story building.

As it jumps, the worm spins at a rate of about 1,000 times a second. And it’s accomplishing all of this while it’s roughly as big as the tip of a needle.

The worm’s secret jumping weapon

The real surprise? These worms are not just jumping – they’re employing static electricity to heighten their opportunity for making contact with their insect prey.

Researchers recently learned this by capturing video of the worms in action using ultra high-speed cameras and running computational models to determine how it all works. The study was led by researchers from Emory University and the University of California, Berkeley.

“We’ve identified the electrostatic mechanism this worm uses to hit its target, and we’ve shown the importance of this mechanism for the worm’s survival,” said Justin Burton, a physics professor who led the modeling work.

How does static electricity help?

When an insect like a fruit fly flaps its wings, it builds up an electrical charge – hundreds of volts just from interacting with the air.

That charge attracts the worm, which picks up the opposite charge through electrostatic induction. The opposite charges pull the worm toward the insect, giving it that final nudge needed to stick the landing.

“Higher voltage, combined with a tiny breath of wind, greatly boosts the odds of a jumping worm connecting to a flying insect,” explained Professor Burton.

Behind the scenes of a worm jump

To actually capture what was happening, biomechanics expert Victor Ortega-Jiménez had to get creative. He glued tiny wires to fruit flies so he could control their voltage.

“It’s very difficult to glue a wire to a fruit fly,” he explained. “Usually, it took me half an hour, or sometimes an hour.”

The setup had to be just right. The worms needed moist – but not too wet – paper to sit on. And even then, they wouldn’t jump unless they felt a light puff of air or a tiny movement.

Ortega-Jiménez filmed the jumps at 10,000 frames per second. That’s how fast you need to go to catch something this small, spinning that quickly, and moving through the air.

He even built a miniature wind tunnel to test how air flow affected the worm’s success.

Evolution of jumping predatory behavior

Ranjiangshang Ran, a physicist and co-lead author of the study, went through the videos and marked every jump by hand when the worms moved out of focus.

Next, he used a computer algorithm called Markov chain Monte Carlo to test different variables and see what conditions helped the worms land on their targets.

Without static electricity, only 1 in 19 worms hit their mark. When the charge reached 800 volts -something common for flying insects – success shot up to 80 percent.

“Our findings suggest that, without electrostatics, it would make no sense for this jumping predatory behavior to have evolved in these worms,” Ran said.

The team also found that even a faint breeze – just 0.45 miles per hour (0.72 kilometers per hour) – helped a charged worm land on a flying insect more reliably.

These worms aren’t just jumping randomly. Their whole movement is tuned by physics that most people never think about.

Creatures that use static electricity

This isn’t the first time scientists have caught small organisms using electric forces to their advantage. In 2013, Ortega-Jiménez showed that spider webs can electrostatically attract flying insects.

Other research has found that static electricity helps bees collect pollen and allows flower mites to ride hummingbirds. Even ticks can be pulled off the ground by the static charge in the fur of passing animals.

The idea that something as invisible and fleeting as static electricity plays such a big role in nature is gaining traction.

“We live in an electrical world, electricity is all around us, but the electrostatics of small organisms remains mostly an enigma,” Ortega-Jiménez said. “We are developing the tools to investigate many more valuable questions surrounding this mystery.”

Big science from tiny creatures

There’s something poetic about finding hidden physics in creatures so small they’re nearly invisible.

The jumping worm’s ability to use electricity to increase its chances of survival doesn’t just help us understand this one species. It points to a bigger idea: electrostatic forces may be shaping tiny ecosystems all over the world.

“You might expect to find big discoveries in big animals, but the tiny ones also hold a lot of interesting secrets,” said Ortega-Jiménez.

Turns out, some of the biggest shocks in science come from the smallest sources.

The full study was published in the journal Proceedings of the National Academy of Sciences.

Image Credit: Vitor Ortega-Jiménez

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