The Congolese giant toad, the size of a small hand, is a hearty meal for any predator. But one escapes from being eaten by birds, lizards and snakes with a trick that is nowhere else in the world: it looks and works just like the Gabon, one of the most poisonous snakes in Central Africa.
Many animals are dangerously imitating those not to be eaten. Viceroy butterflies are colored like the poisonous monarch, and many harmless snakes mimic venomous snakes. However, it is the first time that a toad mimics a snake.
To make sure the researchers did not see anything, a herpetology team spent ten years comparing dead toads from museums with living toads from eleven locations in the Democratic Republic of the Republic of the Congo as deadly vipers. Initially, the researchers found that the toad's body is triangular in shape, similar to that of the head of the viper (top, left, or right). Then they observed a striking – and consistent – color pattern: Like the Viper, the toad has two dark brown spots and a dark brown stripe that extends across the back. When the toad finally perceives the danger, it emits a long, quiet hiss, similar to the warning hiss that a gaboon otter might make before it strikes the Viper, the researchers write today in the Journal of Natural History. Given their close history of development (which both evolved 4 to 5 million years ago) and the fact that the toad is only found in places where the Viper is located, it is likely that the toads and the toads will be found Vipers developed together, the authors write.
Color and shape of the toad do not match exactly. But most predators probably avoid everything that resembles the snake – because a single mistake could be fatal.