Inside the swirling chamber is a cluster of intoxicated Tubifex worms, numbering in the hundreds; it was thought that just alcohol would be enough to make heads spin, but it turns out that experimental tools can be utilized to create even more intense swirling.
At first glance, this experiment may seem a bit… peculiar, but its purpose is profoundly significant. Scientists aim to gain a deeper understanding of active polymers; the term “polymer” refers to compounds with large molecular weights that consist of repeated basic units in their structure. Polymers exist in nature (such as DNA strands) and can also be artificially produced.
A solution containing worms swirling in a rheometer device
Physicists propose that Tubifex worms (scientific name Tubifex tubifex, a species of segmented worms, commonly found in ponds and rivers across various continents) could be the primary subjects in the study of active polymers, potentially marking the beginning of an entirely new research field called living polymers.
“Active polymers represent a fascinating class of active systems, as they are prevalent in many biological systems with varying lengths,” Antoine Deblais, a scientist from the University of Amsterdam and one of the many authors of the study, told Gizmodo. “At the nano and microscopic levels, biology provides numerous examples of flexible active structures, from actin filaments and microtubules to the flagella of sperm, algae, bacteria, and a vast number of planktonic microorganisms. By using these fundamental systems (like active polymers), we can gain a better understanding of active filaments in general.”
Currently, scientific resources lack experimental systems for researching active polymers, making it exceedingly difficult to observe the movements of these organisms. This “drunken worm swirling” experiment involves worms released in water, simulating active polymers—a system comprising individual entities that can move in their own ways. In addition to being easy to observe, both the worms and the alcohol are readily available.
Worm activities in water and in a 5% alcohol solution.
The research team observed a large number of worms within a rheometer (a tool used to measure the movement of a fluid or viscous substance under applied force). They filled the chamber with Tubifex worms and monitored their movement under different conditions; results indicated that the worms slowed down when the temperature dropped or when the solution contained 5% alcohol.
When the temperature dropped sufficiently or the alcohol concentration increased high enough, the worms ceased to squirm, and the solution exhibited a “shear thinning” phenomenon, where as the spinning increased, the filaments in the solution (i.e., the worms in this experiment) began to move in the same direction, facilitating smoother flow of the solution. However, upon removing the alcohol, the shear thinning effect diminished as the worms began to move in random directions.
Physicists plan to replicate this experiment using conventional polymer chains to observe what happens when random movement phenomena occur.
The research has been published in Physical Review Letters.
