Imagine jets of water endlessly cascading up in a fountain; it's a mesmerizing and soothing sight, inspiring quiet appreciation of the hypnotic flow.

Now, picture that fountain made of thousands of wriggling fly larvae.

That's what scientists found while studying the dinnertime of black soldier fly larvae, or maggots. When vast quantities of these larvae feed together, their surging movement around their food creates a living fountain of writhing bodies. That may sound revolting, but the strategy makes maggots uniquely efficient at devouring meals en masse, scientists reported in a new study. [Ear Maggots and Brain Amoeba: 5 Creepy Flesh-Eating Critters]

Larvae of the black soldier fly (Hermetia illucens) typically hatch, live and eat together in the hundreds and thousands, and each voracious grub can consume up to twice its body mass in a day, lead study author Olga Shishkov, a doctoral candidate in mechanical engineering at Georgia Tech, told Live Science.

Other animals, such as piranhas and flesh-eating dermestid beetles, are also known to feed quickly in large groups, and these carnivores can swiftly reduce a corpse to a stripped skeleton. But the dynamics of group-feeding behavior are not well-understood, so the researchers decided to dive deep into piles of maggots (figuratively speaking) to see what the energetic larvae might reveal.

"If you watch a video of any kind of maggots, they squirm around a lot. They're constantly in motion," Shishkov said. "If this didn't benefit them, they probably wouldn't be wasting their energy."

A single maggot eats about twice its own body mass in a single day.
A single maggot eats about twice its own body mass in a single day.
Credit: Shishkov and Hu, Georgia Tech

Using cameras positioned above and below fish tanks, the scientists filmed feeding sessions of groups of larvae — from 500 to 10,000 individuals — as the maggots swarmed around orange slices. The researchers then used a technique called particle image velocimetry (PIV) to analyze the flow and movement of the group as a whole.

As the larvae fed, their movements seemed random to the naked eye, but algorithms detected "a coherent flow direction," the study reported. Viewed from the top, particle analysis showed the mass of maggot bodies flowing outward. Meanwhile, the view from the bottom revealed a flow inward, along with a vortex of the entire feeding mass.

The writhing of black soldier fly larvae around their food may seem random, but it turns out there's a reason for their wriggling.
The writhing of black soldier fly larvae around their food may seem random, but it turns out there's a reason for their wriggling.
Credit: Shishkov and Hu, Georgia Tech

What was happening? When the larvae swarmed around their food, wriggling maggots at the bottom closed in for the first bites. But as the diners' eager neighbors squirmed around them, the first eaters were carried upward by waves of other hungry maggots. Once they reached the top, they tumbled all the way down — an effect resembling water flow in a fountain, the study authors said.

"New larvae crawl in from the bottom and are 'pumped' out of the top," the authors wrote.

Larvae typically eat for only 5 minutes at a time; a flowing momentum in the group means that larvae that are close to the food and resting get moved aside to make room for maggots with empty bellies. This "fountain of larvae" feeding strategy is unique to maggots, because it involves a level of prolonged, full-body contact that is simply not feasible for other types of animals, the scientists explained in the study.

The findings were published online Feb. 6 in the Journal of the Royal Society Interface.

Originally published on Live Science.