Researchers Discover That Living Worm Towers Exist in Nature, Not Just in Horror Movies
A new study reveals that nematodes assemble into coordinated structures to catch a ride on passersby
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It's the stuff of nightmares: countless worms slithering over each other to form a slimy tower that can move like a single superorganism. And yet researchers from the Max Planck Institute of Animal Behavior have just confirmed it's real. Nematodes—a group of tiny worms that include around 20,000 known species—actually form these cringe-worthy living structures in nature, even if they're less than one inch tall.
Previously, researchers had only observed slime molds, fire ants and spider mites naturally assemble into such structures. Nematodes formed towers in labs, but scientists didn't know why. Did they exhibit this behavior in nature? It became a burning question for some researchers.
“It’s just something that always bugged me. I mean, yes, we’re studying nematode collective behavior in the tower context and other contexts, but is it real?” Serena Ding, a leader from the Max Planck Institute's Genes and Behavior group, tells Gizmodo's Ed Cara. “So when I started my research program four years ago, I really dedicated a push towards just actually finding nematodes at a high density and high numbers doing this stuff out there. And then we were successful.”
Ding and her colleagues captured video footage of the nematode towers in fallen apples and pears in orchards in Konstanz, Germany. They describe their discovery in a study published Thursday in the journal Current Biology, revealing the first direct evidence that nematodes create towers in nature as a means of collective transportation.
“If you think about it, an animal that is 1 millimeter long [0.039 inches] cannot just crawl all the way to the next fruit 2 meters (6.6 feet) away. It could easily die on the way there, or be eaten by a predator,” Daniela Perez, the study’s first author and postdoctoral researcher at the Max Planck Institute of Animal Behavior, tells CNN's Kameryn Griesser. “We saw that they are very reactive to the presence of a stimulus,” she adds, describing the nematodes in the towers. “They sense it, and then the tower goes towards this stimulus, attaching itself to our metal pick or a fly buzzing around.”
Either the entire tower, or part of it, then gets carried away. While researchers already knew that individual nematode worms could catch a ride by grabbing on to passersby, the study is the first to demonstrate that towers serve a similar hitchhiking capacity. “That’s the presumed function that we could confirm,” Ding tells New Scientist's Michael Le Page.
The team brought some of the natural towers into the lab, where they discovered that the coordinated structures consisted of a single nematode species, all of which were at a larval stage called "dauer.” They also watched lab-grown Caenorhabditis elegans nematode clones from all life stages build towers in two hours. The structures could grow exploratory "arms" and assemble bridges to travel over gaps, per a statement.
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Within these towers, the researchers noted that there was no clear role differentiation among the worms. However, “C. elegans is a clonal culture and so it makes sense that there is no differentiation within the tower. In natural towers, we might see separate genetic compositions and roles, which prompts fascinating questions about who cooperates and who cheats," Perez explains in the statement.
In fact, “Discovering [this behavior] in wild populations is really important as it shows this is a part of how these animals live and not just a lab artifact,” says William Schafer, a geneticist at the University of Cambridge who was not involved in the study, tells Scientific American's Jacek Krywko.
With that creepy news comes good news.
“They’re not about to take over the world, because they already did,” Ding tells Popular Science's Lauren Leffer. Nematodes are the most prolific animal on the planet. “Global worming has already happened.”
