These worms can escape tangled blobs in an instant. Here’s how

Alternating clockwise and counterclockwise motions help blackworms quickly escape a knot

Wriggling California blackworms tangle themselves into massive blobs (pictured). Despite the intricate knotting, the worms can free themselves in just tens of milliseconds.

Harry Tuazon

By Emily Conover

April 27, 2023 at 2:01 pm

Like tiny, wriggling Houdinis, California blackworms are master escape artists. Groups of the worms work themselves into gnarly tangles but they can undo the knots in just tens of milliseconds. Now scientists have teased out how they do it.

Found in ponds and other standing water, California blackworms (Lumbriculus variegatus) interlace themselves into clumps to control their temperature or conserve moisture (SN: 1/11/19). The worms are typically just a few centimeters long. Their clumps, which can contain anywhere from 5 to 50,000 worms, take minutes to weave. But when spooked by a potential predator, the worms are outta there in an instant.

Videos and ultrasound images helped scientists unravel the worms’ behavior. The tangling and loosening results from the different types of sinuous paths the worms take, researchers report in the April 28 Science.

When the worms are in tangling mode, they do loop-de-loops in the clump, swimming in circular paths that only occasionally switch direction between clockwise and counterclockwise. To disentangle, the worms go into overdrive, frequently switching between clockwise and counterclockwise, often forming figure eights with their bodies. “It’s kind of like the worms have two gears,” — tangling or untangling — says applied mathematician Vishal Patil of Stanford University.

California blackworms tangle their bodies around one another to form worm clumps, which can take many minutes. Despite the complexity of the knotted blobs, the worms can free themselves almost immediately in response to an unpleasant stimulus (in this case electrical stimulation from a nine-volt battery).

Patil and colleagues created computer simulations that re-created the worms’ elite escape skills. Simulated worms that rarely changed looping direction tangled into a blob, and those that often reversed course quickly exploded out of the knot. Those simulations helped confirm the mechanism behind the tangling and untangling.

Understanding how tangling and untangling works is relevant beyond worms — or this morning’s bedhead. Felt is made from tangled fibers, as are birds’ nests and a host of other materials (SN: 5/12/22). Studying worm snarls might help scientists design tangled materials that can be tweaked. By changing the amount of tangle between fibers, scientists could adjust properties like the stiffness of a material.