Arizona Bark Scorpion

Centruroides sculpturatus — the Arizona bark scorpion — is the only scorpion in the United States whose sting is potentially life-threatening. The species is endemic to the Sonoran Desert of Arizona, southern California, southwestern New Mexico, and northern Mexico (Sonora, Baja California). Adults are small (5-8 cm), pale tan to yellow-brown, with a slender pincer and a thin tail (in contrast to the giant desert hairy scorpion (Hadrurus arizonensis), which is much larger and far less venomous). The sting causes severe local pain, numbness radiating from the sting site, vomiting, hyperactive limb movements, blurred vision, and (in children under 10, the elderly, and immunocompromised individuals) respiratory failure that can be fatal. Anti-venom (Anascorp) became commercially available in the US in 2011 and has reduced mortality to near zero. The species commonly lurks under loose bark, in woodpiles, in attic and wall voids of wood-frame buildings, and under outdoor furniture; the species is famous for entering shoes and gloves left outdoors overnight. Like all 2,500+ species of scorpion (order Scorpiones), C. sculpturatus fluoresces brilliant blue-green under ultraviolet light — caused by the presence of beta-carboline (a fluorescent compound) in the hyaline layer of the cuticle. The function of scorpion fluorescence is debated (UV-detection by the scorpion herself, predator deterrence, or no function at all), but the trait is universal across scorpions and present even in 350-million-year-old fossil cuticles.