(CN) – The Congolese giant toad, which makes for a tasty target of lizards and birds, has a unique way of outwitting predators looking for an easy meal: it mimics the appearance and behavior of a venomous snake.
The new study, which published its results Sunday in the Journal of Natural History, examined the toad for a decade to discover that it had the ability to look and behave like the Gaboon viper, a snake that produces more than any other snake in the world.
“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. 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,” said Eli Greenbaum of the University of Texas at El Paso.
Although other animals are capable of mimcry, this is the first recorded identification of an amphibian able to mimic a venomous snake. The Congolese giant toad is found in central African rainforests, while the viper is more widespread throughout Central, Eastern and Southern Africa.
Biologists examined live toads caught in the wild as well as captive and preserved specimens. What they discovered is the similarity of the color pattern and shape of the toad’s body to that of the viper’s head. More than just appearance, researchers discovered the toad is able to mimic the hissing noise of the Gaboon viper, making its illusion seem even more real to potential predators.
“Given the relatively large size and therefore calorific value of this toad compared to other species, it would make tempting prey to a large variety of generalist predators, including primates and other mammals, lizards, snakes and birds,” said herpetologist Chifundera Kusamba.
He added: “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.”
The scientists theorize that the toads and vipers coevolved with one another, with the toads evolving in appearance as a defense mechanism.