Distressed blue jeans are often less battle-tested than they look, an illusion created by artificial wear and tear in a factory. But a new, extremely limited line of designer jeans from Japan have earned their stripes with a far more authentic kind of adversity: being mauled by tigers, lions and bears.

Named Zoo Jeans, these are "the only jeans on Earth designed by dangerous animals," according to the Mineko Club, a volunteer group in Hitachi City, Japan, that's behind the project. The club came up with animal-shredded pants both to help it "revivify" the local Kamine Zoo and to support wildlife conservation around the world. It recently auctioned three pairs of Zoo Jeans online, vowing to donate all profits to the Kamine Zoo's conservation programs and to the World Wildlife Fund (WWF).

"We first take their favourite playthings — old tires and giant rubber balls — and wrap them in sheets of denim," the Mineko Club explains on its website. "Then we return them to the animals and let nature run its course. The animals roar, gnaw and claw at their toys, and when they're done we gather up what's left of the damaged denim. It is from this unique fabric that we make the jeans."

The group produced this video detailing the grisly origins of Zoo Jeans:

Zoo animals are widely given tires and other props as toys, an effort to promote enrichment and activity in captive wildlife. And while it's impossible to recreate animals' wild lives inside a zoo, activities like this can still offer a boost for mental and physical health. So despite their key role in making Zoo Jeans, the cats and bears of Kamine Zoo probably thought they were just playing.

"We believe that we could help the animals to relieve their stress by providing new toys and fun stimulus to them," Zoo Jeans representative Miyashita Aya tells The Wild magazine. "The toys were carefully made for safety and we never forced the animals to play with them."

And since proceeds from the pants will go to the Kamine Zoo and wildlife conservation projects, the animals are essentially making a product that can benefit themselves and their wild relatives.

"Rather than simply being a marketing [gimmick], there is actually value in this from an animal welfare perspective," writes Robert Young, a professor of wildlife conservation at the University of Salford, in a post on the Conversation. "Involving lions and the zoo's other large carnivores in the activity is part of what's called environmental enrichment. ... It's a win-win activity for many zoos, who can make alternative profits from their animals, which tend to be used to provide extra facilities for them."

The Mineko Club has yet to announce another auction of Zoo Jeans, but if you happen to be in Hitachi City this week, you can see them on display at the Kamine Zoo through July 21.

Related animal stories on MNN:

Zoo animals rip jeans to raise money for conservation
Revenue from the animal-torn jeans will help support Japan's Kamine Zoo and the World Wildlife Fund.