Many animals can consume some of the world’s deadliest toxins—and live to tell the tale. Scientists are uncovering the remarkable tricks these creatures use to neutralize poisons that would kill most other species.

The Snake and the Poison Frog

In a recent experiment, researchers gathered 10 royal ground snakes (Erythrolamprus reginae) from the Colombian Amazon and gave them an almost impossible choice:
starve, or eat three-striped poison dart frogs (Ameerega trivittata)—a species packed with powerful toxins like histrionicotoxins and pumiliotoxins.

Six snakes refused the deadly meal.
Four went for it.

Before swallowing the frogs, the snakes dragged them along the ground, possibly trying to rub off toxins—behavior similar to birds that clean poisonous prey before eating it.

Amazingly, three of the four snakes survived, suggesting they have biological defenses that reduce or neutralize the toxins.

The Ancient Arms Race of Toxins

Life on Earth has been locked in chemical warfare for hundreds of millions of years:

• Microbes make toxins to kill competitors.
• Animals produce venom or defensive chemicals.
• Plants evolve bitter or poisonous compounds to deter herbivores.
• And some animals incorporate toxins from their diet.

These interactions have shaped entire ecosystems, says evolutionary biologist Rebecca Tarvin of UC Berkeley.

“Just a milligram of a toxin can shift an entire set of ecological relationships.”

How Animals Beat Poison

Animals have developed a suite of ingenious strategies to survive toxins—some even turning those chemicals into tools of their own.

1. Altering Their Own Proteins

Many poisons bind to essential cell proteins. Some animals evolve mutated versions of those proteins so toxins can’t latch on.

Examples:

• Milkweed insects evolve sodium-potassium pumps resistant to cardiac glycosides.
• Poison frogs have toxin-resistant channels in nerves and muscles.
• Insects feeding on toxic plants modify their nervous systems to stay functional.

But these mutations often come with trade-offs.
Studies show that more resistant proteins can become less efficient, creating challenges for normal cell function.

For example, in the large milkweed bug, its toxin-resistant pump works poorly—so the insect keeps a more vulnerable but highly efficient version in its brain, shielding it in other ways.

2. Pumping Out Poisons Before They Do Damage

Some animals use transporter proteins such as ABCB transporters to eject toxins from their cells.

Evidence shows:

• Hawk moths use ABCB proteins to push glycosides away from nerve tissues.
• Onion beetles appear to pump toxins out through the gut, allowing them to excrete dangerous compounds completely—and their toxic feces even repel ants.

3. Neutralizing Poisons Inside the Body

Tarvin’s research suggests royal ground snakes rely heavily on the liver:

• Enzymes may chemically break toxins apart.
• “Sponge proteins” may bind toxins before they can harm cells.

Some poison frogs have similar molecules in their blood that grab onto saxitoxin and other alkaloids, protecting them from their own toxic diet.

4. Matching Toxins in a Biological Arms Race

The California ground squirrel has evolved blood proteins that neutralize local rattlesnake venom. These proteins resemble those that rattlesnakes produce to protect themselves in case venom leaks inside their own bodies.

But the battle never ends:

• Rattlesnakes evolve new venom formulas.
• Squirrels update their defenses accordingly.

Even resistant animals can die from enough venom, so avoidance still matters.

Examples of avoidance strategies:

• Snakes scraping poison off frogs before eating.
• Turtles eating only safe parts of toxic newts.
• Monarch caterpillars draining toxic sap from milkweed leaves before feeding.

Using Toxins as Weapons

Some species go even further—not only resisting toxins but harnessing them.

Examples:

• Dogbane beetles store plant toxins in droplets on their backs as a defense.
• Poison frogs convert dietary toxins into potent skin secretions.
• Monarch butterflies rely on milkweed toxins for protection; predators learn to avoid them.

This co-opting of poisons can even reshape ecosystems.
A study led by UC Berkeley’s Noah Whiteman found that several species have evolved to tolerate cardiac glycosides so they can feed on toxin-rich monarch butterflies.

One example is the black-headed grosbeak, which eats monarchs during the butterflies’ winter migration in Mexico.

A toxin produced in a milkweed plant in Canada ends up influencing the evolution of a bird thousands of miles away.

“It’s amazing how far a single molecule can travel—and how much evolutionary power it carries,” Whiteman says.

The Big Picture

Across the natural world, poisonous relationships form the backbone of countless evolutionary battles and alliances.

Some species:

• Resist toxins
• Break them down
• Avoid them
• Store them
• Even weaponize them

Together, these strategies show just how deeply chemical warfare is woven into the fabric of life.