This little rodent chomps away at bark scorpions—the most venomous scorpion in the United States—without a care in the world. While humans suffer extreme pain, convulsions, and sometimes even death as a result of a sting from this nasty creature, the grasshopper mouse is seemingly unfazed.
Scientists now believe they know how this is possible. In a study published yesterday in Science, Ashlee Rowe, an evolutionary biologist at Michigan State University, and her colleagues write that these rodents have a mutation in the cellular pathway that controls their pain response, making them immune to scorpion venom.
It’s a good thing they do. Grasshopper mice live in the deserts of the Southwest, an arid landscape crawling with bark scorpions. Food isn’t as abundant there as in other ecosystems. To get an accurate reading of the grasshopper mice’s neural mechanisms, Rowe and her colleagues injected both the grasshopper mouse and the house mouse with a small amount of venom and compared their responses. The house mice seemed uncomfortable; the grasshopper mice seemed fine.
But that’s not all. Here’s Sarah Zhang writing for Nature News:
In a second experiment, the researchers injected house mice and grasshopper mice with venom and then with formalin, a chemical known to cause pain. The grasshopper mice still licked their paws less than the house mice, suggesting that the venom blocked the ability of the grasshopper mice to feel pain from the formalin.
In other words, scorpion venom is like Tylenol to grasshopper mice. Here’s Ed Yong, writing for Phenomena:
The mouse is armed with a protein that stops its nerves from firing whenever it recognizes the toxins in a bark scorpion’s venom. This doesn’t just stop the venom from triggering intense pain; it means that the scorpion’s venom actually prevents pain! The southern grasshopper mouse turns a scorpion’s sting from a painful killer into a painkiller.
Researchers are lauding this study for its interdisciplinary approach and its completeness, and for its potential applications in the pain-relieving drug industry. Watch “Venom: Nature’s Killer” to learn more about other venomous animals and the medical mysteries they reveal.