When the time is right, worms gather together to create a wriggling mass, a tower of worm-ness. No, really. They climb onto each other until their bodies behave like one single organism. They then stay like this for up to 12 hours, extending exploratory “arms” whenever there’s a stimulus nearby.
But why do they do it?
A nematode tower is more than just a pile of worms
“I was ecstatic when I saw these natural towers for the first time,” says senior author Serena Ding, group leader at the MPI-AB, of the moment when co-author Ryan Greenway sent her a video recording from the field. “For so long, natural worm towers existed only in our imaginations. But with the right equipment and lots of curiosity, we found them hiding in plain sight.”
Well, I don’t know exactly whose imagination had towers of worms, but researchers were indeed speculating that nematodes build these structures.
Nematodes (worms) are thought to be the most abundant animal on Earth, with an estimated 10 million species, although only 27,000 have been described by scientists. They’re a diverse and resilient group with plenty of unusual behaviors. Some species can survive being frozen for thousands of years, while others can withstand Chernobyl radiation. Some can literally taste sunshine while others can turn plants into zombies. But worm towers, until now, had not been observed.
The behavior is not unprecedented. It’s a phenomenon known as “collective dispersal,” where individuals form a group to migrate or to escape tough conditions. Slime molds, fire ants, and spider mites are among the few animals to do it. But worm towers are different.
For starters, they’re made of genetically identical individuals — clones. Each worm in the tower seems to be equally mobile and contributing to the overall structure, so there seems to be no competition at play. There’s no leader, no pre-planned choreography, and the result is coordinated, functional, and weirdly elegant.
Finding the worm towers — then recreating them
The researchers observed two species of Caenorhabditis worms towering on decomposing apples and pears. Under natural conditions, these worms often enter a stress-resistant phase called the “dauer” stage, which helps them survive and move in tough environments. It’s these dauers that do the climbing and clumping.
The worms are about the size of a grain of salt, so Greenway spent months with a digital microscope combing through decaying pears in orchards near the university, looking for worm towers. Some of them, he brought into the lab.
Although the orchard was teeming with all sorts of nematodes, only these species seemed to create towers. But using lab experiments with C. elegans — the lab rat of the worm world — the team refined a reliable method to grow worm towers on toothbrush bristles. This allowed them to study the towers in more detail and analyze how they respond to stimuli, grow in different environments, and whether all worms or just some play special roles.
The results were striking. Towers could grow up to a centimeter tall, realign themselves if bumped, and even stretch across gaps to reach new surfaces. When touched gently with a glass pick, the towers extended in the direction of the stimulus. In some cases, dozens of worms used the opportunity to migrate en masse to a new food source.
“A nematode tower is not just a pile of worms,” says the first author Daniela Perez, a postdoctoral researcher at MPI-AB. “It’s a coordinated structure, a superorganism in motion.”
“The towers are actively sensing and growing,” says Perez. “When we touched them, they responded immediately, growing toward the stimulus and attaching to it.”
Furthermore, the tower seems to move in unison. All the worms are excellently coordinated. Despite this, the worms show no differences. The ones at the base of the tower seem to be just like the ones at the top: a true egalitarian cooperation (although researchers point out, this could be different in the wild).
We don’t understand much about this
It seems likely that worms form these towers as a strategy to escape harsh environments and disperse to new habitats, especially when food runs out. The towers act like living launchpads, helping the worms reach higher surfaces or hitch rides on passing insects or other creatures. While we can’t say with absolute certainty that this is the only reason they tower, the evidence is strong: towers form when conditions are stressful, they respond to touch by attaching to potential vectors, and they can bridge gaps to new terrain. It’s not just a random pile of worms — it’s a coordinated move to leave and find better conditions.
Despite the new insights, there’s still a lot we don’t understand about worm towering. For one, how do the worms coordinate without a leader or signals? There’s no obvious communication system, yet they form stable, organized structures.
We also don’t know what sensory cues trigger towering — touch clearly plays a role, but the potential involvement of smell, taste, or even electric fields remains murky. Another mystery: why do non-dauer worms tower in the lab, but not (yet) in the wild? Are we just missing it, or is something else going on? And finally, do individual worms differ in their motivation or roles, especially in genetically mixed groups?
For now, these worm towers are one of those intriguing phenomena in nature, the invisible drama that unfolds all around us while we mind our own business. That something so complex, so purposeful, can emerge from a crowd of brainless clones is a reminder that evolution doesn’t always need blueprints to build marvels. It just needs pressure, time, and the will to climb.
Journal Reference: Towering behavior and collective dispersal in Caenorhabditis nematodes, Current Biology (2025). DOI: 10.1016/j.cub.2025.05.026. www.cell.com/current-biology/f … 0960-9822(25)00601-3
