How worm blobs behave like a liquid and a solid
Scientists are studying how the animals move collectively when tangled together by the thousands
BY SUSAN MILIUS 1:11PM, JANUARY 11, 2019
ALL TANGLED UP Worms tangled together in a blob can move collectively, flowing through pipes like a liquid but also showing properties of solids.
NATIONAL GEOGRAPHIC IMAGE COLLECTION/ALAMY STOCK PHOTO
TAMPA, Fla. — Blobs of worms flow like a fluid, plop like a solid and fascinate scientists.
A worm by itself is as solid as any other living animal. But a mass of aquatic California blackworms tangled together flows through a tube like a liquid. Pouring, heating and otherwise playing with blobs of worms shows that a tangled mass of them has properties of both fluids and solids, Saad Bhamla reported January 5 at the annual meeting of the Society for Integrative and Comparative Biology.
A blob can hold itself together like a solid: When released to fall a short distance on a hard surface, it plops instead of splashing, Bhamla, a biophysicist at Georgia Tech in Atlanta, said. And video from his lab also revealed a worm blob version of melting. In a container of water where a hot spot develops, the blob starts fraying and “melts” away as some blackworms (Lumbriculus variegatus) disentangle themselves and swim off, while others collectively move to a spot with a lower temperature. Adding chilly water, however, will cause the blob to solidify again as the animals rejoin the ball.
Blobs of worms that ooze along as a mass might help advance the study of biological physics, Bhamla said. Unlike some more famous animal group behaviors, such as birds flocking or fish schooling, worms tangling in a blob nudge against each other and transfer forces directly. Such contact matters in some of biophysics’ profound questions about how little bits of soft matter come together as multicellular life.
More:
https://www.sciencenews.org/article/how-worm-blobs-behave-liquid-and-solid?tgt=nr
