Tailless Whipscorpions (Family Phrynidae) are very common at night in Costa Rica, and I saw quite a few of them while I was there. I spotted this large Tailless Whipscorpion lurking at the base of a tree next to my cabin one evening.

Despite their terrifying appearance, Tailless Whipscorpions are entirely harmless to humans, and only invertebrates like cockroaches need fear them. Tailless Whipscorpions are not actually scorpions and don't have stingers. The claw-like structures near their mouths are actually grasping, spiny pedipalps that they use to capture their prey.

Like spiders, Tailless Whipscorpions are eight-legged arachnids, but they are not spiders either. Tailless Whipscorpions are in their own order, Amblypygi, and are referred to as amblypygids. Two of a Tailless Whipscorpion's eight legs are extremely long and function as antennae. The Tailless Whipscorpion uses these slender, delicate, whip-like, antenniform front legs as sensory organs to probe for its prey in the dark. These "whips" are slender and difficult to see, but the right "whip" touches the upper right corner and the left "whip" touches the left edge in the photo below.

Our naturalist guide for a nighttime hike through the Costa Rican jungle told us of an amusing (and completely untrue) folk tale that Tailless Whipscorpions will whip people with their poisonous whips and the only way for a whipping victim to survive is to immediately urinate on wherever the Tailless Whipscorpion touched. For some people, I think that the need for this urine "cure" could just be a likely story to cover up a very understandable loss of bladder control from having such a horrifying-looking creature crawling on them. Even though I know that they are completely harmless, I certainly wouldn't want a Tailless Whipscorpion on me (shudder).

Tailless Whipscorpions are mainly tropical and subtropical species, and they are also found where I live here in Tucson, Arizona.