Acid Venom

A scorpion’s sting can be agonizing. Scientists now think they know why: The animals’ already painful venom contains a mild acid—a substance that is typically sour-tasting and corrosive.

Toxins in a scorpion’s venom target the same pain receptors in the body that cause a burning sensation when a person touches something hot. But when scientists analyzed the venom’s chemistry, they found that the toxins alone didn’t account for the punishing pain of a scorpion’s sting. They discovered that the venom’s acid took the sting’s fiery fury to another level.

“The acid opens the pain receptors, activating nerve cells that transmit pain,” says Jie Zheng, a professor at the University of California, Davis. “This makes the scorpion venom even more effective.”