Behold, the Worm Blob and Its Computerized Twin

In the wild, a worm blob looks like any other mud ball lolling around the bottom of a pond. But if you poke an unassuming worm blob, it will respond in a way a mud ball never would, wriggling out into a noodly shape that a Pastafarian might mistake for something divine.

This is how Saad Bhamla discovered his first worm blob, in a pond in California. “As you poke it with a stick, it comes alive,” said Dr. Bhamla, a bioengineer at the Georgia Institute of Technology’s school of chemical and biomolecular engineering. Dr. Bhamla’s encounter with the worm blob haunted him for years (in a good way, he says) until he started his own lab and needed a first project.

California blackworms, soft and slender ropes as surreally red as grocery store meat, often live in seasonal pools. When times are good, a worm is simply a worm, wiggling about on its own. When times are bad, a worm must become a blob, entangling with hundreds or thousands of other worms into a slimy, writhing ball. And, like an animated ball of yarn, the worm blob can move as one unit, meandering away from predators or stress.

“They remain braided and twisted into this cohesive unit that’s crawling around,” said Chantal Nguyen, a postdoctoral associate and physicist at the BioFrontiers Institute at the University of Colorado Boulder.

But how does a worm attain and maintain blobdom? In a recent study in the journal Frontiers in Physics, a group of researchers including Dr. Nguyen and Dr. Bhamla unraveled the secrets of the blob’s ability to move. They did so by creating a computer model of entangled California blackworms.

“It was pretty horrific and pretty shocking, but also kind of beautiful,” said Albert Kao, a postdoctoral fellow studying collective behavior at the Santa Fe Institute in New Mexico, of the worm blobs. The simulation, he added, “lays a path forward for new kinds of models for similarly entangled systems.”

Since time immemorial, people have witnessed groups of animals moving collectively and in unison: starlings flock, fish school, midges swarm, and heavy metal heads mosh. But few people have had the privilege of, or the interest in, observing worm blobs.

A worm blob behaves as a solid and a fluid, like a ball of dough or a glob of shampoo. It only takes around 10 worms to form a coherent blob. A blob of about 100,000 worms resembles a lump of (red) pizza dough. There is no known limit to how many worms can form a blob, except, perhaps, your imagination.

When Serena Ding, a researcher at the Max Planck Institute of Animal Behavior, first saw a photo of blackworm blobs, her mind raced. “I was first just shocked,” said Dr. Ding, who was not involved with the paper. “And then I was grossed out, and then I was fascinated.”

Dr. Ding, who studies blobbing in the much-studied nematode Caenorhabditis elegans, described her C. elegans blobs as “strongly overlapping, like a bowl of spaghetti noodles.” Blackworm blobs “are more like spaghetti noodles dropped on the floor,” she said, frowning, in a Zoom call. “C. elegans is named for being elegant. These ones are just … not.”

But it was precisely this messy splat of blackworm blobs that captured…