How 'crazy ants' band together to carry food

The degree of cooperation found among longhorn crazy ants is rare outside of humans and ants, according to a new study.

Courtesy of Asaf Gal and Ofer Feinerman
A foraging longhorn crazy ant often encounters food items that are considerably larger than herself (a Cheerio in this case).

It’s all about teamwork.

That’s what a new study by the Weizmann Institute of Science in Israel has found after years of people curiously watching ants take off with their food raised questions about how the tiny insects were able to carry away morsels many times bigger than themselves.

The ants the researchers have been examining, also known as longhorn crazy ants or Paratrechina longicornis, have a distinct pattern of zigzagging as they move, and until now, scientists didn't understand why that might be.

According to the study, published Tuesday in Nature Communications, the ants optimize their ability to transport heavy loads, such as cat or dog food – or in this case, light-colored Cheerios scented with cat food for bait – by conforming to each other’s behavior. “It is the give and take of cooperation,” as National Geographic puts it.

To determine how this teamwork comes about, researchers filmed groups of ants carrying nearly 100 different loads of varying sizes, also adding obstacles to the paths back to their nests to see how they’d manage to maneuver around them.

Scientists tagged individual ants and found that they were trading off positions of leading, steering, and carrying. When a heavier object was placed to see if the ants would chomp it down into smaller pieces or collaborate to carry it as a whole, they decided to work together. 

The degree of cooperation required is rare outside of humans and ants, the study authors wrote. To be able to efficiently work together, no tug-of-wars are permitted.

And ants shouldn’t get any funny ideas about slacking off: Another ant, monitoring the group’s progress, will prod them right back on track.

“The ‘romantic view’ of ants, explains systems physicist Ofer Feinerman, an author of the study, is that each single ant is stupid, but together ‘emerges some kind of collective intelligence,’ ” reported National Geographic.

Simon Garnier, who researches collective behaviors of ants and other organisms at New Jersey Institute of Technology's Swarm Lab, praised the study for its data collection method, according to Popular Science.

“What is especially impressive is that [the study] is based entirely on field data. They captured the behavior of the ants in their natural context and managed to come up with very clean data,” he said. “It is an excellent example of how tracking technologies, in this case computer vision, are making it possible to collect good data on animal behavior in the wild.”

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