This Savvy Toad Pretends to Be a Deadly Viper

The Congolese giant toad (Sclerophrys channingi) looks prety unassuming when it's not pretending to be a viper. Konrad Mebert

A plump toad would seem like a tasty treat for any hungry predator. After all, toads aren’t typically fleet of foot. And they're typically a delicious bite that won't bite back.

But some toads have a funny way of making sure they don’t go down easy.

Take the Congolese giant toad. Found exclusively in the Democratic Republic of the Congo, this chubby amphibian has been described as a “triple-cheeseburger-sized prize” for forest-foraging animals.

But it’s no Happy Meal.

The Congolese giant toad has the uncanny ability to turn itself into the spitting image of one of the region’s deadliest snakes: the Gaboon viper.

Don’t believe it? Feast your eyes on this image:

A side-by-side comparison between a toad and a snake.
The toad (on the left) was born with markings that closely resemble the Gaboon viper. Colin Tilbury

Yes, that’s a toad on the left. And don’t worry if you’re still not convinced.

A successful defense mechanism

It took a team of international researchers a decade to uncover this critter’s illusion. Publishing their findings this week in the Journal of Natural History, they tout the toad’s savvy survival skills as a stunning example of Batesian mimicry.

That’s the phenomenon, named after naturalist Henry Bates, that has typically inoffensive animals pretending to be much deadlier creatures. It’s typically a defense mechanism, often employed by insects to avoid being plucked by much bigger creatures.

But few pull it off in the convincing — and downright scary style — of the Congolese giant toad.

“Our study is based on ten years of fieldwork and on direct observation by researchers lucky enough to see the toad's behavior first-hand,” notes study co-author Eli Greenbaum of the University of Texas at El Paso in a press release. “We're convinced that this is an example of Batesian mimicry, where a harmless species avoids predators by pretending to be a dangerous or toxic one.”

And this toad couldn't have picked a more terrifying inspiration than the Gaboon viper. Not only is the viper handsome — yes, snakes can be beautiful — but it produces “prodigious amounts of venom.”

Full-on impersonation

A Gaboon viper on the forest floor
A young adult Gaboon viper on the forest floor, where it spends most of its time waiting to ambush prey. Colin Tilbury

That said, the Gaboon viper isn’t known to be very aggressive, getting by mostly on reputation — a reputation that the Congolese giant toad is all-too happy to cash in on.

But how did a toad go about finding this unlikely muse? Researchers studied toads caught in the wild, captive specimens as well those preserved in museums. They noted the creature’s markings, including two dark brown spots and a stripe running long the toad’s back, already looked a lot like the markings of the viper. There’s even the fact that this toad’s skin is unusually smooth for its kind, almost as if it was born a pretender.

"To fully test our hypothesis, we'd have to demonstrate that predators are successfully duped, but this would be very difficult in the wild, where the toads are only encountered rarely,” Greenbaum explains. “However, based on multiple sources of evidence provided in our study, we are confident that our mimicry hypothesis is well-supported."

But the toad isn’t just physically gifted for impersonation. It’s also an accomplished method actor — something that separates it from most of nature’s mimics.

When a viper is threatened, it will raise its head and hiss long and loud as a preface to a lightning-quick bite. And so too, will the Congolese giant toad, according to research team member Chifundera Kusamba, who witnessed the behavior — minus the bite, of course.

What’s more, the giant toad knows the full value of location. Researchers noted it only frequents regions that the viper is known to haunt. After all, what good is pretending to be a deadly snake when the locals have never met that deadly snake before?

It all adds up to nature’s ultimate thespian — a method actor who was not only born for the role, but lives it every day.

"Many of these predators use vision to find their prey, and because the viper is deadly venomous, they probably recognize the distinctive, contrasting markings from a considerable distance and avoid the toad because of them, receiving a threatening hiss if the appearance doesn't put them off,” Kusamba explains.

Want to see more of this savvy survivalist? Check out the video below: