This worm’s lifestyle is the stuff of science fiction

TAMPA, FLORIDA—Half the size of a cigarette and squirmy, the black aquatic worm Lumbriculus variegatus isn’t much to look at. But these denizens of sulfur caves and flooded areas like company and often many thousands come together as “blobs” with behavior not unlike the 1958 movie by the same name. Tangled up in squishy masses that can be the size of a basketball or bigger, the worms are transformed into a pulsating ball versatile enough to squeeze through tubes, hold together and bounce off surfaces, or spread out or shrink depending on the conditions.

The odd behavior helps these animals weather extreme conditions, researchers reported here today at the annual meeting of the Society for Integrative and Comparative Biology.

The worms breathe through their skin and need to stay wet. A single worm lives less than an hour in air at room temperature and humidity. But a blob of 20 survives more than 5 hours, and the survival time goes up as the number of worms increases, the researchers discovered. The outer ones may dry out, but inner ones stay moist. The worms glom together to minimize the exposed surface area that loses moisture, and thus really big blobs can even withstand being dried with a hairdryer, the researchers note.

The blob is also versatile. A 50,000-worm blob placed in a container with a gradient of temperature will migrate toward the preferred temperature, acting as a solid mass. But in other situations, it “liquifies” and flows—through tubes, for example, they discovered.

Based on their growing understanding of these blobs, the scientists are building robots that may eventually exhibit similar collective behavior and may one day solve complex problems or perform intricate building or searching tasks.