The frog that murders everything and also tells you if you're pregnant

North Carolina's original illegal amphibian has the answer you're looking for, and also has a lot to answer for.

Newly-minted Charlotte magazine publisher Andy Smith had a very important question for me a few weeks ago:

Here’s a tip that you can pursue for Rabbit Hole: The state, as you know, has lax exotic animal laws. But on its site, the NC Wildlife Resources Commission makes a special note to not own or distribute a Tongueless or African Clawed Frog. Can you unpack what would happen if one got into the wild?

What kind of ecosystem mayhem would it cause? And are they cute?

That sounds like one badass frog. Here’s what it looks like:

An African Clawed Frog which has, you know, claws. (Photo via Brian Gratwicke - Flickr)

I mean, I’ve seen cuter amphibians. Still though, it’s one type of frog. How bad could it be?

It can be pretty bad!

Not great! That’s the opinion of Jeff Hall, an amphibian and reptile conservation biologist with the state Wildlife Resources Commission. Jeff helps to figure out what goes on North Carolina’s list of banned animals. (“It’s got some newts in there,” he says of that list.) African Clawed Frogs have been outlawed in North Carolina since 1994, and were the first actual non-native species banned from possession in this state. They’re the O.G. of illegal amphibians.

So what happens when they’re introduced into an unsuspecting ecosystem? Well, consider a low-key ominous headline in the Charlotte Observer from 1979: “These Frogs Live To Eat and Multiply.” What follows is wire service story from California and it gets really bleak, really quickly:

One day this spring, an Orange County golf course groundskeeper strolled down to the course’s water hazard to check on the mosquito fish. Thousands had been placed in the lake to keep it free of mosquito larvae. But he couldn’t find a single fish — dead or alive.

Seriously, this is how horror movies start. Turns out, the thing that killed and ate them all was … the frogs. Now, before we get too worried, let’s hear from a calm, rational, voice of reason:

“In all the years I’ve studied them I haven’t found anything they won’t eat” [biologist James] St. Amant says. “They will eat bugs and snails, tadpoles, other frogs, small fish — anything. Left alone in a small body of water, they would kill everything until you’d find only the clawed frog left. Then they’d begin eating each other.”

GAHHHHHHHHH.

Basically, the frogs shred any other small animals they encounter with their claws and then just devour them. They’re hard to catch, since they’re fast, can hold their breath for a long time, and can swim backward. They stink and taste funny, so predators who can actually catch them don’t like to eat them. Also they, uh, reproduce:

Much like the great white shark in “Jaws,” the clawed frog lives only to kill, eat, and make baby clawed frogs. The latter occurs with amazing frequency. In a four-month mating period, a single female can lay thousands of fertile eggs.

Folks, these frogs exist only to Netflix and kill.

So if they’re so bad, who brought them here?

An African Clawed Frog comin’ to kill you. (Photo by David J. Stang)

Great question! For that, we have to go back to the 1930s, and a British scientist with an ultra-British name: Lancelot Hogben. He’d been in South Africa experimenting with hormones. There were a ton of clawed frogs around, and they responded well to his experiments, so that’s what he used. Along the way, he discovered something: If you inject the urine of a pregnant human woman into them, they’ll lay eggs within a matter of hours. Hence, the African Clawed Frog became the first reliable (and reusable) pregnancy test. Within a few years, labs around the world stocked up and shot thousands of frogs full of lady pee.

In the 1960s, scientists were able to make a chemical test to detect the specific hormone that a woman’s body makes when she’s pregnant, so the frog was no longer useful on a large scale. So what did those labs do? They just set the frogs free, where they found stagnant ponds and ditches and whatnot and started going on killing and mating sprees.

The frogs are still of use to scientists, though, because they’re basically biological research rock stars. At N.C. State, for example, scientists in the late ‘80s wanted to know if the frog’s mucus held clues to helping solve Parkinson’s disease and schizophrenia. They got interested after they saw that snakes who tried to eat the frogs began to yawn uncontrollably after tasting the mucus, allowing the frog to escape. Again, why don’t snakes eat frogs? They taste funny.

We’ll make great— er, very bad pets

Those African Clawed Frogs are still used at universities in North Carolina, along with a few museums and aquariums, although they have to get a special permits to have them. We’re among 11 states that ban the frogs. I wasn’t able to figure out what ultimately led to the ban in 1994, but Hall says since then, several more animals have been added, including Asian newts, Brown Anoles, and Cuban Treefrogs. Most recently, Red Eared Sliders made the list. The turtles are invasive and can spread salmonella, and end up getting released quite a bit by pet owners. They look cute, but get big and live for 40 years, and as pets, they need more care and more space than people might think.

The red eared slider (Photo via Wikipedia/Navi8apr)

For a while, people thought clawed frogs made for great aquarium animals, too. After all, they’re smaller and quieter than bullfrogs, and they were once popular as mail-order pets, even in places where they’re banned. In Nevada, for example, there was a bust a while back that was traced to a company called Grow-a-Frog (naturally) that was based in Florida (of course).

Anyhow, the frogs can wear out their welcome. A lot of people decide to get rid of them after they KILL EVERYTHING ELSE IN THEIR AQUARIUMS.

So, yes, biologists are here to tell you one simple thing: Don’t get an African Clawed Frog. They’re bad. For you. And your goldfish. And for, you know, the natural world at large. Still, Jeff Hall says he’s trying not to be a downer. “We’re not trying to be the pet store detectives,” he tells me. “We’re trying to make sure native species are protected. That’s why we have the list.”

One more note: You can love on native species, but you can’t keep them as pets. That’s explicitly illegal in North Carolina. So, you’ll have to shelve your dreams of keeping a pet squirrel or raccoon and just go get yourself a totally non-problematic animal: a cat.