This is a bark scorpion.
Grasshopper mice eat bark scorpions. They often get stung in the process. Luckily for the mice, the scorpion venom acts like an analgesic for them. Yes, that’s right, the mice feel better after a few stings in the face.
Researchers from Michigan State University led by Ashlee Rowe tested the painkilling effects of scorpion venom by injecting mouse foot pads with either the venom or a simple saline solution. Mice react to foot pain by licking their feet and sure enough the unfortunate mice in the experiment did spend time licking their feet. But the scorpion-injected mice licked a lot less than the saline-injected mice.
How is this possible? The sensation of pain is created when sodium ions pass through special channels in cell membranes. Most mammals have one type of sodium channel, but the grasshopper mice have a particular genetic variation. Scorpion venom can bind to the amino acids in the mouse channels, effectively blocking them.
Needless to say, this result has interesting implications for medicine, and not just for people who get stung in the face by scorpions. If researchers can find compounds that block our sodium channels, that could be a powerful painkiller.