“Faster than a viper’s strike” is a phrase that used to mean something—researchers long thought that vipers were the swiftest of all snakes. Now, it turns out that some harmless snakes can strike just as quickly as venomous vipers—fast enough to literally make your head spin. Researchers used high-speed cameras to measure the strike speeds of two viper species—cottonmouth vipers and diamondback rattlesnakes—along with Texas rat snakes (pictured), a nonviper species that lacks venom. They were all evenly matched in speed, and even the slowest strike approached an acceleration of 100 meters per second squared, the researchers report today in Biology Letters. That’s twice the most intense g-forces experienced by fighter-jet pilots, more than enough to make any human black out. The attack doesn’t take long, either. Strikes of all three snake species lasted less than a tenth of a second, about half the time it takes for a human to blink. But more importantly, that’s also faster than the snakes’ mammal prey, like jackrabbits and kangaroo rats.