Texas is home to some of the creepiest, crawliest, and otherwise oddest animals on the planet. We introduce you to them in What in Tarnation?!, an occasional series.

Maybe you’ve heard that old urban legend about the guy who adopts what he thinks is a puppy. The location changes: sometimes it’s Mexico, sometimes the Bay Area. The “guy” can be anything from a tourist unfamiliar with the fauna of the region he’s visiting to a mom coerced by her puppy-loving kids. But one aspect is consistent: the “puppy” is not actually a puppy. It’s a giant, monstrous rat. 

In Texas and Louisiana, this urban legend usually ends with a nutria. Quite literally a rodent of unusual size, nutria (Myocastor coypus, scientifically) can reach 22 pounds and two feet in length (not counting their ratlike tail, which can grow as long as a foot and a half). The species is originally from South America and was brought to the United States by shortsighted fur traders in the late nineteenth century. The nutria fur market began to collapse in the 1940s. Some traders released them directly into the wild, while others tried to market them to ranchers and farmers as “weed killers.” Either way, they began to multiply with astonishing speed; now they’re a widespread, pernicious invasive species terrorizing the ecosystems of the Gulf coastal states. They feed on crops—particularly those that are water intensive, such as rice and sugarcane—and their burrowing can destroy levees and reservoir dams. And, speaking from my own personal experience, nutria also serve as the perfect menace with which Texas boys can terrorize their little sisters. 

My older brother, who I doubt ever saw a nutria himself, heard about them at summer camp and then constantly reminded me that “giant rats” lurked in every body of water around us. So in my childhood mind’s eye, nutria resembled an uncivilized—and thus more terrifying—Splinter from Teenage Mutant Ninja Turtles. I have thankfully never seen one in the flesh, but when I did eventually come across its image in a photograph, I thought that “giant rats” was a stretch. Honestly, they look more like beavers. They’re small and brown, with little black noses. Some people think they look like the capybara, a bigger South American rodent to which the nutria is actually distantly related. (At least one person has believed a capybara would hang out at an Austin-area mall.) 

Nutria need a habitat that’s water-rich, so they are most populous in the eastern half of our state and over into Louisiana, though they can be found as far west as Brewster County. They seem to pop up a lot in the Houston suburbs, with recent sightings in Pasadena and Katy. Weighing between 15 and 22 pounds, nutria look most like a cross between a muskrat and a beaver, though their tails, which are thin, nearly hairless, and can be as long as their torso, are inarguably ratlike. But I dare say nutria are at least a little bit cute, and from a purely aesthetic perspective, it seems like they get a bad rap with the whole “giant rat” thing. Sure, they have that tail, and some very gross, big, orange teeth, but beavers have gross teeth too, and nutria have little white noses and white whiskers that make them look more distinguished than beavers. And as everyone knows, when you’re talking about animals, “more distinguished” automatically means “cuter.”

What isn’t cute is what nutria can do to our ecosystem. Unlike beavers, which feed on the bark, leaves, shoots, and other parts of plants, nutria go for the whole thing. “Nutria have the big teeth, but they’re not eating trees,” says Mikayla Killam, a wildlife program specialist at Texas A&M’s AgriLife Extension. “They’re eating vegetation. They’re going through and chomping down on all these little seedlings. And so it can be significant enough that you stop seeing the native plants recruiting in that area. They’re not able to come back because they’re being eaten in such great quantities by these very abundant nutria.”

Beavers, Killam pointed out, build lodges and dams. They’re “habitat engineers” that give back by improving water quality and preventing erosion. Nutria, however, just take and take and take. Nationwide, they destroy more than $1 million in crops—rice, sugarcane, and other resources—every year, according to the Texas Invasive Species Institute. “ ‘Giant aquatic rat’ is not the worst description you could come up with for this animal,” Killam says.

You have to give it to nutria, however. In the arena of semiaquatic creatures, they’re killing it. They can close their mouths behind those big orange teeth, allowing them to chew off aquatic vegetation without swallowing water. They build floating nests on marshes that they use like little dining tables. Their back feet are large, and webbed, so they are extremely efficient swimmers. Killam is impressed by some facets of their evolution. “Their mammary glands are actually on the side of their body instead of on the front, so that they can nurse their offspring while floating in the water,” she says. Women really can have it all, I guess!

Like many invasive species, nutria reproduce rapidly. They typically start breeding when they reach about nine months, though the process can begin as early as four or five months. They produce litters that average around five offspring but can be as high as thirteen. So if a four-month-old nutria has thirteen babies, who in turn have thirteen babies when they are four months old, who in turn have thirteen babies when they are four months old, that’s more than two thousand baby giant rats born in one year. Neither our ecosystem nor our infrastructure is designed to support that many giant swamp rats and the damage they can inflict. 

As with feral hogs, scientists have tried various strategies to keep nutria in check, but none has been particularly successful. The state lists nutria as a nuisance fur-bearing animal, which means that Texans can shoot or trap as many as they want on their own land, no hunting license required. Nutria reportedly tastes like rabbit, inspiring Texas Monthly to once deem it one of the state’s most delicious invasive species. That story includes a recipe for nutria chili, courtesy of Louisiana chef Enola Prudhomme.

I have still never seen a nutria, though I recently tried. A couple weeks ago, I met one of Killam’s colleagues, Brandi Keller, at Houston’s Hermann Park, near McGovern Lake, where nutria are frequently spotted. We walked a loop a couple of times, scanning the banks for any vegetation that might be rustling. It was a beautiful morning, and the park was full of wildlife. We saw some black-bellied whistling ducks that wanted nothing to do with us, and Muscovy ducks that waddled uncomfortably close. 

One squirrel followed us around pretty much the entire time. He would stop in front of us and stand on his back legs, a little trick to win our favor. It was, inarguably, cute. I thought about the squirrel, a rodent that is sometimes referred to as “just a rat with good PR,” and wondered if he might have any tips for nutria.