Tag Archives: Gel technology

Amusing Monday: Researchers untangle the mystery of hagfish slime

“Hundreds of meters deep in the dark of the ocean, a shark glides toward what seems like a meal. It’s kind of ugly, eel-like and not particularly meaty, but still probably food. So the shark strikes.

“This is where the interaction of biology and physics gets mysterious, as the shark finds its dinner interrupted by a cloud of protective slime that appears out of nowhere around an otherwise placid hagfish.”

I don’t usually begin my “Amusing Monday” blog posts with a quote from a news release, but writer Chris Barncard has described precisely what leads up to an encounter between a fish predator and the mysterious hagfish. Biting a hagfish sends a shudder of revulsion through an enemy trying to eat it. The news release, found on the website of the University of Wisconsin – Madison, describes the research that has led to a mathematical description of an attack by hagfish slime.

“In the blink of an eye (or the flash of attacking tail and teeth), the hagfish can produce many times its own body’s volume in slime,” writes Chris Barncard. “The goop is so thick and fibrous, predators have little choice but to spit out the hagfish and try to clear their mouths.”

Jean-Luc Thiffeault, a UW-Madison math professor, has been working to mathematically model the hagfish response, which can occur in half a second.

“The mouth of the shark is immediately chock full of this gel,” he said. “In fact, it often kills them, because it clogs their gills.”

I’ve pulled together some amusing videos of hagfish to show this strange fish in action. The video at the bottom of the page was offered by the researchers to show how the slime is able to expand so suddenly. As usual, go full-screen for the best view.

When the hagfish is attacked, gel is ejected from glands in its skin. The gel consists of seawater-trapping threads that are coiled up into “skeins” each having a diameter about twice the width of a human hair. Each tiny skein is coiled so tightly that it can release up to six inches of thread.

Previous researchers found that it took several hours for the skeins to unwind if they were placed in still water, whereas stirring the water speeded up the process.

Study collaborators Randy Ewoldt, a mechanical engineering professor at the University of Illinois, and his graduate student Gaurav Chaudhary studied the process under a microscope and worked with Thiffeault to describe the fluid dynamics.

“Our model hinges on an idea of a small piece that’s initially dangling out, and then a piece that’s being pulled away,” Thiffeault was quoted as saying. “Think of it as a roll of tape. To start pulling tape from a new roll, you may have to hunt for the end and pick it loose with your fingernail. But if there’s already a free end, it’s easy to catch it with something and get going….

“The main conclusion of our model is we think the mechanism relies on the threads getting caught on something else — other threads, all the surfaces on the inside of a predator’s mouth, pretty much anything — and it’s from there it can really be explosive.”

Improving the hydrodynamics of the system are proteins found in mucous that can help break apart the skeins.

“Nothing is going to happen as nicely as in our model — which is more of a good start for anyone who wants to take more measurements — but our model shows the physical forces play the biggest role,” Thiffeault said.

While hagfish may act like an alien creature, understanding the behavior of tangled threads in a microscopic world could lead to new applications for gel technology in the world of industry and medicine, according to the researchers. At least one company, Benthic labs, is working on developing a synthetic slime that could be used in consumer products, such as packaging and clothing, in place of materials derived from petroleum.

One species of hagfish, Pacific hagfish, can be found off the West Coast from Canada to Mexico in waters from 50 to 3,000 feet deep.