The rough-skinned newt produces tetrodotoxin from skin glands as a defence against predation.
From the en.wikipedia.org
An amphibian that eats them is the rough-skinned newt.
From the en.wikipedia.org
Toxin resistant garter snakes are the only known animals today that can eat a rough-skinned newt and survive.
From the en.wikipedia.org
An example is the production of tetrodotoxin in the rough-skinned newt and the evolution of tetrodotoxin resistance in its predator, the common garter snake.