Rodents are known for being pests, but the nutria may be the worst of them. The orange-toothed, semi-aquatic rodents from South America, which can grow to be up to 20 pounds, have become invasive species whose territory extends to almost every continent on earth. Along the way, they’ve created environmental catastrophes, destroyed infrastructure and crops, and created millions of dollars in damages. The pesky creatures are the subject of a new documentary, Rodents of Unusual Size. The 71-minute film traces the nutria’s rise in Louisiana and the profound consequences it has had on the ecosystem there. Here are seven facts about the animals we learned from the documentary.

1. THEY’RE NOT FROM AROUND HERE.

Nutria are native to South America, but over the past century or so, they have traveled around the globe. In some places, they’re better known as coypu, from the Spanish word coipú. (In Spanish, the word nutria means otter.)

While Rodents of Unusual Size focuses on a small community in southern Louisiana, nutria pose a significant problem elsewhere, too. In the late 19th and early 20th centuries, fur farmers and trappers brought them to Europe, Asia, and Africa as well as a number of places in North America to raise them for their pelts. (Some U.S. states also imported them as a method of weed control.) Unfortunately, that led to the rise of feral populations that have since ballooned. The Invasive Species Specialist Group has named nutria one of the world’s top 100 worst invasive species.

2. THEY MAKE A LOT OF BABIES.

One of the reasons nutria pose such a big problem as an invasive species is that they multiply rapidly. They reach sexual maturity at only a few months old, can reproduce up to three times a year, and in extreme cases, can have litters of up to 13. Though they typically only live between three and six years in the wild, they’re such prolific breeders that, as one invasive species project notes, even in that short time frame, “the amount of offspring produced is tremendous.”

3. AS AN INVASIVE SPECIES, THEY’RE REALLY BAD FOR THE ECOSYSTEM.

Growing up in Delacroix, an island community just south of New Orleans, “it was a jungle,” lifelong resident Thomas Gonzales explains in the opening minutes of Rodents of Unusual Size. “There was nothing but big oak trees. When I look out now, it looks like a disaster.”

Nutria, which can consume up to 20 percent of their body weight in plant matter and roots each day, eat up the vegetation that holds together wetland soil, causing major erosion. What was once wetland becomes open water, permanently. “All the grass that the muskrats used to eat, they cleaned it like a baseball field,” Gonzales says. “Now it’s all water.”

He’s not exaggerating. While storms, dredging, and other factors have also played a role in the environmental decline of places like Delacroix, between 2001 and 2016, overgrazing nutria contributed to the conversion of almost 26,800 acres of Louisiana marsh to open water, the state estimates. And since marshes serve as important protection against storm surges, that also leads to greater flooding inland.

Nutria also pose problems in other arenas: The animals dig extensive burrow systems that sometimes end up under roads, around bridges, and in canals and levees. They also destroy thousands of dollars worth of crops like sugarcane and rice each year, and do millions of dollars of damage to golf courses.

4. THEY WERE ONCE BIG BUSINESS.

The nutria’s rise to global domination is largely thanks to the fur industry. In Louisiana, for instance, fur farmers brought them up from Argentina to raise for their pelts in the 1930s. Some of those animals either escaped or were released, taking up residence along the Gulf Coast, where they flourished in the swamps and other wetlands. By the 1960s, nutria were the Louisiana fur industry’s biggest commodity, with trappers bringing in more nutria and selling the pelts for more money than any other animal. In the 1970s, nutria trapping brought in 1.9 million pelts per year [PDF]. Unfortunately, the overabundance of nutria meant that supply eventually outstripped demand—which was falling across the fur industry anyway—and prices fell steeply over the next few decades. Trapping nutria was no longer as profitable, so trappers found work elsewhere. And without the fur industry keeping the nutria in check, the animal's populations exploded.

5. PEOPLE STILL DEPEND ON THEM FOR THEIR LIVELIHOODS.

Thomas Gonzales of Delacroix Island, Louisiana

Now, as the environmental impact of nutria has become more apparent, the state of Louisiana is trying to bring back nutria trapping. In order to incentivize trappers to hunt down nutria, the state has a $5 bounty on nutria tails. During the nutria hunting season, from November to March, the state sets up collection stations where trappers can bring in the tails of nutria they have killed [PDF]. They get a check in the mail based on the number of tails they bring in, and can use the carcasses however they want—whether that’s selling them for their fur or meat or discarding them. (Sometimes fur dealers are even on hand at collection stations.) Since the program first began in 2002, it has resulted in the removal of 5 million nutria.

6. WEARING THEIR FUR IS CONSIDERED ETHICAL.

Nutria were originally valued for their pelts, and nutria fur may be making a comeback. In most of the world, killing nutria does a service to the environment, making the rodents one of the most ethical sources of fur around.

“Traditionally, the stigma of fur is that people don’t feel comfortable killing animals to adorn themselves,” fashion designer Cree McCree explains in the film. “But the thing with the nutria is that they’re being killed anyway, and they’re throwing these beautiful furs away. It seemed like a colossal waste.” So McCree founded Righteous Fur, a collective of fashion designers who incorporate nutria fur into their designs, making everything from coats and hats to bow ties. Since most faux fur is made of polyester or other plastics, wearing nutria might actually be more sustainable than sporting fake fur.

7. YOU CAN—AND SHOULD—EAT THEM.

Cree McCree, founder of Righteous Furs

While people may be turned off by the idea of eating a giant rodent with big orange teeth, nutria actually make a pretty good addition to the dinner table, according to chefs and hunters. “If you approach it with an open mind, you’ll find it doesn’t have a really bad, swampy taste,” award-winning New Orleans chef Susan Spicer says in Rodents of Unusual Size. “The nutria flavor is sort of like the zucchini of the animal world. You can kind of make it work with a lot of different kinds of flavors.”

The meat is lean, and, unlike with other meats, you don’t have to worry about feeling bad that a cute critter died for your dinner. In fact, you’re doing the environment a service. And in the right hands, nutria is reportedly delicious. Some hunters in the film even say it’s preferable to steak.

Rodents of an Unusual Size makes its Los Angeles debut on September 14. To find a screening near you, check out the film’s website.

All images courtesy Rodents of Unusual Size/Tilapia Film