Lens of Time: Velvet Worms—Secret of the Slime
With their chubby bodies, soft, padded feet, and slow-motion gait, South American velvet worms appear pretty harmless. Unless they’re hungry, and you’re an insect. Over millennia, these ancient creatures have evolved a pair of hunting weapons unlike any other in nature: dual high-speed cannons capable of jetting viscous slime onto their prey from up to two feet away. Delivered with such power and speed, the velvet worm’s slime cannon takes the element of surprise to new levels. And because the goo is delivered through narrow, flexible tubes and expelled with such tremendous force, it can cover a vast area in a matter of milliseconds.
Until recently, biologists still didn’t know exactly how these slime cannons work. But then Andres Concha, a Chilean physicist who studies the physical mechanisms in biological systems, turned his attention to velvet worms. His goal: to better understand how fluids operate in the microscopic world. After collecting live specimens from southern Chile’s remote temperate rainforest, Concha and his team used high-speed cameras to film slime cannons in action. Their observations and measurements have provided new insights into the physics underlying this unique and deadly hunting tactic—and may one day lead to new biotechnology applications. Concha now applies his understanding of this mechanism—a unique adaptation that evolved some 500 million years ago—to construct working replicas of the slime cannons in his lab.