Blobs of worms untangle in milliseconds with a corkscrew wiggle

Worms that create intricately entangled blobs with their bodies can untangle in milliseconds when threatened. This rapid decipherment is possible because each worm wriggles with a special corkscrew motion.

California blackworm (Lumbriculus variegatus) entangles its body in knotted “worm clumps” to keep it hydrated during droughts. In the wild, these balls can contain up to 50,000 worms. It takes several minutes for the animals to form clumps, but when Harry Tuazon of Georgia Tech hit one of these twisted wormballs with ultraviolet (UV) light in his lab, he found that the worms were I was shocked to see it loosen up in just a few tens of milliseconds.

He and his colleagues wanted to understand how worms escape blobs 100 times faster than they form blobs. They used ultrasound to look inside a clump of about 20 worms and identify details of its structure, such as how many times each worm coiled around other worms. To do this, they wrapped the blobs in gelatin so that the worms would writhe less. , which filmed rapid entanglement while researchers manually tracked the head trajectory of each animal.

The team also collaborated with mathematicians who specialize in knot theory. These researchers used data from their observations to build mathematical models and run computer simulations. The results revealed that the main difference between slow and rapid untangling of worms was the direction in which each animal performed a kind of spiral wriggling.

Repeated motion of the corkscrew in one direction for a while and then abruptly changing direction creates tangles, but quickly alternating the corkscrew from side to side effectively unravels the blobs, says Vishal of Stanford University in California. says Patil.

“Mathematically, detangling is so complicated that I thought it was a problem that could not be solved in practice, but Harry and colleagues showed me these videos and Worms solved the problem. I thought if we could solve it, we could do it,” he says. .

Antoine Deblais of the University of Amsterdam, the Netherlands, said, “This new understanding of how black worms transform from dense masses to become more dispersed will help researchers to finally find materials that can do things on their own.” In the future, materials made from intertwined soft filaments will be looser and more bendable if those filaments can wriggle like worms. Or it could be stiffer and more compact.