This Mouse’s Defense Against Scorpion Venom Could Influence Modern Medicine

A mouse native to the Sonoran desert has found a way to turn scorpion venom from painful to pain-killer, rendering the scorpion's natural defenses completely ineffective.

The Arizona Bark Scorpion has the most powerful venom of any scorpion species in the United States, and a tiny drop is enough to send a full-grown human to the hospital in excruciating pain. Containing various neurotoxins, the venom is used both to paralyze prey and help protect the scorpion from being eaten.

But one tiny desert hunter has evolved to resist the scorpion's venom: the Southern Grasshopper Mouse, also called the Scorpion Mouse colloquially because of its taste for scary snacks.

Now scientists at Michigan State University have figured out how the mouse can take a lethal dose of venom and keep fighting. A protein built into its nervous system binds with the toxins injected by the scorpion and blocks them. Instead of feeling pain, the mouse's nerves go numb, producing an analgesic effect.

It takes a while to kick in, so the mouse does feel pain for a few seconds. In the video, it takes three stings to the face and has to back off for a moment to rub its cheeks. But once the numbing effect kicks in, the mouse launches a second attack and kills the scorpion, despite taking several more stings in the process.

Researchers think the mouse's adaptation could contain some important clues for manufacturing more efficient pain medicine for humans. So this is good news for us—but bad news for scorpions, who will need to up the evolutionary ante.