Carl Zimmer in his excellent blog, The Loom:
The scientific tale of the rough-skinned newt begins five decades ago, with a story about three dead hunters in Oregon. Reportedly, the bodies of the hunters were discovered around a camp fire. They showed no signs of injury, and nothing had been stolen. The only strange thing about the scene was the coffee pot. Curled up inside was a newt.
In the 1960s, a biologist named Butch Brodie got curious about the story. The newt in the coffee pot–known as the rough-skinned newt–has a dull brown back, but when it is disturbed, it bends its head backward like a contortionist to reveal an orange belly as bright as candy corn. Bright colors are common among poisonous animals. It’s a signal that says, in effect, “If you know what’s good for you, you’ll leave me alone.” Brodie wondered if the newts were toxic, too.
Toxic, it turns out, doesn’t do the newts justice. They are little death machines. The newts produce a chemical in their skin called tetrodotoxin, or TTX for short, that’s made by other poisonous animals like pufferfish. Locking onto sodium channels on the surface of neurons, TTX blocks signals in the nervous system, leading to a quick death. In fact, TTX is 10,000 times deadlier than cyanide. While we may never know for sure what killed those three Oregon hunters, we do know that a single rough-skinned newt could have easily produced enough TTX to kill them, and have plenty of poison left over to kill dozens more.