Side-by-side comparison between a subadult toad and subadult Gaboon viper.

The body of the Congolese giant toad (left) mimics the head of the Gaboon viper (right). The snake’s venom is potent enough to kill a human. Credit: Eli Greenbaum

Zoology

The giant toad that impersonates a deadly viper to fool predators

Is it a harmless Congolese giant toad? Or a lethal snake?

The Congolese giant toad is a filling snack for predators — if they dare to attack it. The grapefruit-sized amphibian, it turns out, is a master of disguise: it holds an uncanny resemblance to the head of the highly venomous Gaboon viper.

After years of fieldwork in the eastern provinces of the Democratic Republic of the Congo, Eli Greenbaum at the University of Texas at El Paso and his colleagues discovered that the toad (Sclerophrys channingi) occurs only in areas where the viper (Bitis gabonica) is present. The toad also looks like the viper: the toad’s body has some of the characteristic colours and horn-like structures of the snake’s head. And, like the snake, it emits a hissing noise resembling the sound of air being released from a balloon.

The amphibian’s disguise is not perfect, the researchers note. But for many hungry predators, hunting this creature might not be worth the risk.

Correction: An earlier version of this story gave an incorrect credit attribution for the image. The image should have been credited to Eli Greenbaum.