By Rachel Kaufman
Many people are disgusted by the hagfish. These squirmy, eel-looking creatures are known primarily for two repellent traits: eating dying animals from the inside out, and oozing four cups of slime in a fraction of a second.
But Douglas Fudge, an integrative biologist at Canada’s University of Guelph, in Ontario, has given us a reason to embrace the goo: It may one day be used to produce a strong, eco-friendly fabric. The recent study by Fudge and colleagues, published April 15 in the Journal of Experimental Biology, has revealed that different hagfish species have very different methods for producing their defensive goo.The Pacific hagfish (Eptatretus stoutii), seen in California. Photograph by Norbert Wu, Science Faction/Corbis
Emitted when the fish is stressed or trying to avoid predators, hagfish slime is made up of two parts: mucus and tiny fibers, each of which is about 6 inches (15 centimeters) long but only a micron wide. That’s much thinner than a human hair or blood cell.
The fibers give the slime its ability to clog the gills of any predator that dares to eat it, said Fudge, who has been studying the icky critters since 1997. (Related video: “Attacking Shark Gagged by Slime.”)
“It’s hard to describe in words,” he says. “People think they know what it’s going to be like, but they’re always shocked when they feel it.”
Although the slime itself doesn’t smell, “if you catch a hagfish on a boat and bring it up to the surface, it’s usually really stressed out . . . They tend to add things to the slime,” Fudge says. In other words, they defecate or vomit into their slime.
“It has the potential of being really disgusting, because they tend to feed on things that are already rotten to begin with.”
For his recent study, Fudge and colleagues studied the Atlantic and Pacific hagfish—two of the 77 known species.
In both Atlantic and Pacific hagfish, the slime strands are made inside special cells in the fish’s body; the cells produce tiny, coiled-up skeins that look like balls of yarn. When the skeins are spewed out of the Atlantic hagfish’s body with the slime—about 25,000 of them in one “sliming event”—the slime and the hagfish’s thrashing cause them to unravel. (See “Slime Has Memory but No Brain.”)
But in Pacific hagfish, the skeins come open in a different way. Fudge’s team found that in Pacific hagfish, the skeins are initially glued together with a protein-based adhesive that dissolves in seawater. The glue comes off, the threads unravel, and a hungry predator suddenly has a face full of mucus instead of a tasty meal.
How hagfish make these adhesives or produce a 6-inch-long (15 centimeter) thread so tightly coiled that it fits inside a single cell are still unanswered questions.
Meanwhile, these slimy threads could have a practical use for humans. Hagfish slime threads are almost as strong and light as spider silk, which researchers have been trying to adapt for use in clothing for years. (Related: “Twisting Everyday Fibers Could Make ‘Smart Clothes’ a Reality.”)
“Spider silk is made within silk glands in this mysterious process,” Fudge said. “In hagfish slime, there’s a lot more self-assembly involved.”
Also, the genes that make a hagfish thread-producing cell are smaller than spider silk genes, so it should, in theory, be possible to implant those genes into a bacterium and produce reams and reams of hagfish slime silk, for use anywhere we’d currently use nylon—think stockings or workout pants, for example.
And since nylon is ultimately derived from petroleum, a hagfish-slime substitute could actually be good for the planet.
Hagfish Clothing Still Years Off
Fudge’s lab has successfully harvested small amounts of hagfish thread and spun it like silk, and earlier this year the team published a paper describing stronger fibers made from a related protein.
But hagfish-slime stockings and jackets are probably still years off. And Fudge admits that the fabric will need a marketing makeover. That said, there’s a historical precedent: “In the 1980s, eelskin wallets were all the rage,” he said. (See “As Fashion Week Ends, Pondering the Origins of Clothes.”)
“Everybody had an eelskin wallet, and it turns out that was actually hagfish leather. Some clever person realized that nobody’s going to buy anything called genuine hagfish skin.”
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