It’s time to meet another member of the arachnid class: Hadrurus arizonensis, the desert hairy scorpion. These nocturnal desert dwellers are the largest scorpion in North America and are found throughout the southwest United States. Like all scorpions, its venom is contained in a bulb at the end of its tail. The scorpion will use the stinger at the end of the bulb to deliver venom to its prey, or sometimes strike out at larger animals (and people) if it is being antagonized.
Like all arachnids, scorpions have 4 pairs of walking legs, and you might be surprised to find out that those big pincers don’t count! The pincers, known as pedipalps, are mouthparts! They use them to manipulate their prey after they have immobilized it with venom, and they use a smaller set of pincers, the chelicerae, to tear and chew food items.
Scorpions are famously known for fluorescing a bright blue-green under UV light; the best way to find these nocturnal predators is to venture out to the desert with a blacklight. Yet little is known about why this adaptation evolved. Recent studies suggest that the glow is the scorpions way of knowing whether or not it is hidden from other, larger nocturnal predators, like owls and large rodents. Not only can scorpions see blue-green light incredibly well (so they can see themselves fluorescing on clear nights), they can sense the reaction of UV light on their exoskeleton and know if they are exposed, even when their eyes are damaged or covered.