The Most Poisonous Creature?

Q: What is the most poisonous creature on Earth?
- Darko, Dubrovnik, Croatia

A: Imagine you are in Colombia, South America. Midday, in the depths of a jungle west of the Andes along a Pacific river. It is dark, hot, and dismal. Dusk never leaves the day below the tree canopy. Rainwater pools in huge, still leaves. A heavy atmosphere clings to the earth like a coiling miasma.

"Thwoop," breaks the silence as a poison dart hurtles from a blowgun to its target: a howler monkey secure on a lower branch of a tree towering a hundred feet above the rain forest floor. The dart penetrates the monkey's reddish fur, into her flesh and bloodstream. She falls, paralyzed, unable to breathe, and her heart fails.

The poison from the skin of the world's most poisonous known creature — the tiny, 1.5-inch, Golden Poison Frog (Phyllobates terribilis) — kills the monkey.

An average P. terribilis contains about one milligram of poison, which is enough to kill 10,000 mice-perhaps enough to kill 10 to 20 humans if the poison reaches their bloodstreams.

This extraordinarily lethal poison (a steroid alkaloid, called batrachotoxin) almost does not occur in nature. We have found this poison only among three poison frogs in Colombia and two poison birds in Papua, New Guinea.

The yellow frog stores the poison in skin glands, as do most frogs. Due to their poison, frogs taste awful to predators so most don't eat them. But, any foolish enough to do so, die.

The poison attacks the sodium channels of animal cells. Through the ages, however, the clever frog has evolved special sodium channels that the poison cannot harm.

Frogs normally have no occasion to eat their own poison but this frog is different. The frog apparently eats the same poison as his own but produced by some other creature. He eats the unknown creatures as we might eat shrimp or chicken: just standard food. Frogs grown in captivity, however, can't eat the same food and they are not poisonous.

"All evidence indicates that such frogs obtain the poisons unchanged from some creature in their diet," says Daly. "Thus, the high toxicity of P. terribilis appears due to consumption of an unknown mysterious small insect or other arthropod, which may truly be the most poisonous creature on Earth. It is a mystery that we hope to someday solve."