RESEARCH NEWS

Collective Worm and Robot “Blobs” Protect Individuals, Swarm Together

 Individually, California blackworms live an unremarkable life eating microorganisms in ponds and serving as tropical fish food for aquarium enthusiasts. But together, tens, hundreds, or thousands of the centimeter-long creatures can collaborate to form a “worm blob,” a shape-shifting living liquid that collectively protects its members from drying out and helps them escape threats such as excessive heat.

While other organisms form collective flocks, schools, or swarms for such purposes as mating, predation, and protection, the Lumbriculus variegatus worms are unusual in their ability to braid themselves together to accomplish tasks that unconnected individuals cannot. A new study reported by researchers at the Georgia Institute of Technology describes how the worms self-organize to act as entangled “active matter,” creating surprising collective behaviors whose principles have been applied to help blobs of simple robots evolve their own locomotion.

The research, supported by the National Science Foundation and the Army Research Office, was reported Feb. 5 in the journal Proceedings of the National Academy of Sciences. Findings from the work could help developers of swarm robots understand how emergent behavior of entangled active matter can produce unexpected, complex, and potentially useful mechanically driven behaviors.

The spark for the research came several years ago in California, where Saad Bhamla was intrigued by blobs of the worms he saw in a backyard pond.

“We were curious about why these worms would form these living blobs,” said Bhamla, an assistant professor in Georgia Tech’s School of Chemical and Biomolecular Engineering. “We have now shown through mathematical models and biological experiments that forming the blobs confers a kind of collective decision-making that enables worms in a larger blob to survive longer against desiccation. We also showed that they can move together, a collective behavior that’s not done by any other organisms we know of at the macro scale.”

Such collective behavior in living systems is of interest to researchers exploring ways to apply the principles of living systems to human-designed systems such as swarm robots, in which individuals must also work together to create complex behaviors.

“The worm blob collective turns out to have capabilities that are more than what the individuals have, a wonderful example of biological emergence,” said Daniel Goldman, a Dunn Family Professor in Georgia Tech’s School of Physics, who studies the physics of living systems.