Poison in Nature
As you meet the occupants of a remote Colombian forest, think of this: none of their weapons really target us.
It’s Not Easy Being Green . . . But It’s Awesome Being Yellow
Ounce for ounce, the the skin of these jewel-bright amphibians (left) from the Chocó lowland forest is among the most toxic substances on Earth. Want to know how toxic? Just count the number of frogs on display in the exhibition and multiply by 10. That’s the number of humans who could—theoretically—succumb to the poison secreted by all of these frogs. But don’t worry. In the wild, a dart frog’s poison comes from specific species of invertebrates in its diet. Our frogs, which are fed crickets and flies, are harmless.
What is it? The poison found in the skin of golden poison frogs, batrachotoxin (bah-TRAY-ko-tox-in) gets its name from the Greek word for frog, batrachos.
What does it do? Makes nerves unable to transmit impulses. Death comes from cardiac arrest.
How potent is it? On a weight basis, batrachotoxin is 250 times more powerful than the rat poison strychnine.
Poison in Nature
What if you were under attack, day in and day out, yet couldn’t even hide, much less run away? Sounds like a nightmare—but it’s how plants live their lives, rooted in the ground and besieged by insects, larger plant-eaters and even other plants.
Still, land plants have been around for about 450 million years, plenty of time to evolve an astonishing array of chemical defenses.
What is it? This oily, sticky toxin occurs in many plants, including cashews (left) and poison ivy.
What does it do? It causes skin blistering when eaten—and, for some humans, when they brush against it.
Should I worry? If you’re sensitive, avoid not only urushiol-containing vegetation, including the skin of mangoes, but also smoke from burning these plants.
Most venomous animals (including the yellow fat-tailed scorpion below) share two important traits. They have special glands for manufacturing venom and something sharp with which to inject it. That something may be spurs, stingers, spines, or teeth.
And what is venom, exactly? Venoms are complex biological cocktails that can include enzymes, other proteins, and chemicals such as serotonin. Some venom components might induce pain; others may home in on the clotting factors of blood, on cell membranes, or on the signaling machinery of nerves.
Nearly all ants and termites wage chemical warfare; their weapons include poisonous sprays and secretions in addition to venom. Why such firepower? Ants may use these biochemicals as part of a mutually beneficial relationship with plants that provide them with food or shelter.
Venom allows this little ant (left) —and the plant it lives in—to survive. In the Chocó lowland forest, ants nest in the little “room” that can be seen through a magnifier in the exhibition. Scientists call such nests domatia, from the Latin word for “home.” In some locations, the ants spray the formic acid they produce on encroaching vegetation, eliminating those plants from the neighborhood. In other words, the ant/plant relationship benefits both parties. When ants eliminate all but the plant species in which they nest, they create an area some have termed a “devil’s garden” or a “ spirit garden.”
Breaking Down Defenses
Almost all animals eat plants, and those plants very often contain toxins. These range from bitter-tasting substances called tannins that interfere with digestive enzymes to poisons that can cause illness—or even death. That’s why many plant-eaters, including humans, have come up with some surprising ways to break down plants’ chemical defenses.
Howler monkeys (left) eat a leafy diet full of plant toxins. They also eat clay from termite mounds, perhaps to eliminate those toxins.
Visit The Power of Poison exhibition for more about poison in nature.