Nematodes Form Collective Towers to Hitch Rides on Insects

In a groundbreaking study, scientists from the Max Planck Institute of Animal Behavior (MPI-AB) and the University of Konstanz have observed nematodes forming living towers to enhance their survival and mobility. This behavior, previously documented only in laboratory settings, was recorded in natural environments, specifically in decaying fruits such as apples and pears. The findings, published in the journal Current Biology on June 17, 2025, reveal that these structures serve as a means of collective transport, allowing the worms to hitch rides on insects to escape unfavorable conditions.

Historically, nematodes, despite being the most abundant animals on Earth, have faced challenges in mobility when resources are scarce. For decades, researchers had speculated about the existence and function of these so-called 'towering behaviors' in the wild. Senior author Serena Ding, a group leader at MPI-AB, expressed her excitement at witnessing this phenomenon in nature, stating, "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."

The research team, led by Ding and technical assistant Ryan Greenway, meticulously examined decaying orchard fruits over several months to capture footage of these natural towers. Their observations indicated that these towers are not mere piles of worms; instead, they represent a coordinated structure of a superorganism. According to Daniela Perez, a postdoctoral researcher at MPI-AB and the first author of the study, "A nematode tower is not just a pile of worms; it's a coordinated structure, a superorganism in motion."

The study identified that the natural towers were composed of a single species of nematode at the larval stage known as 'dauer.' The researchers noted that these towers exhibited remarkable behaviors, including synchronized movements and responses to external stimuli. When touched, the towers could detach from surfaces and collectively latch onto passing insects, effectively hitching rides to new environments.

To further investigate the dynamics of these structures, Perez created controlled towers using laboratory cultures of *Caenorhabditis elegans* (C. elegans). Within just two hours, these towers were formed, demonstrating stability and the ability to extend 'arms' into their surroundings. These findings suggest that the capacity for towering may be a broader strategy for group movement among nematodes than previously believed.

Despite the complexity of these towers, the worms within them exhibited no clear role differentiation, indicating a form of egalitarian cooperation. However, the researchers caution that natural towers may display diverse genetic compositions and roles, raising questions about cooperation and competition within these structures.

This research opens new avenues for understanding collective behavior in organisms, from microscopic nematodes to large-scale animal migrations. Ding noted, "By harnessing the genetic tools available for C. elegans, we now have a powerful model to study the ecology and evolution of collective dispersal."

The implications of this study extend beyond the realm of nematodes, offering insights into the evolutionary strategies of group movement among various species. As researchers continue to explore the dynamics of collective transport, these findings may contribute to a deeper understanding of social behaviors in the animal kingdom.

This study contributes significantly to the field of evolutionary biology and collective behavior, establishing a new model for examining how and why animals move together. The researchers' observations not only shed light on previously unrecognized behaviors in nematodes but also invite further investigation into the ecological and evolutionary significance of collective strategies across diverse species.