Have you ever come upon a biologist outside doing strange things? Did you just ignore them, or did you stop to ask them what they were doing?

Once while on a visit back home, I ended up meandering through the Texas hill country. It was only natural that I would start turning over rocks, which certainly raised an eyebrow or two. Only one person bothered to ask me what I was doing. This curious soul learned that I had one thing in mind as I searched eagerly, and it was this:

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A Neobisiid pseudoscorpion collected by Casey Richart & Bill Leonard, in Thuja + Abies + Tsuga habitat, St. Joe National Forest, Idaho (Wiki Commons)

The elusive pseudoscorpion!

I spent my first few years in grad school researching these fascinating arachnids. In case you’re confused, not all arachnids are spiders. Within this class of animals, there are also harvestmen, solfugids, ticks, mites, and a handful of others. But pseudoscorpions. Well, they’re as cute as can be. (I definitely just used a Texan drawl to say that.)

So what’s so cool about these critters? Well, for one, they’re secretive. They tend to live in small crevices and cracks, or under leaf litter or rocks. They like it dark and damp. Not unlike their spider relatives.

What’s more is their strange body shape, for which they are named. The front of their body is scorpion-like, but they lack the tail and stinger of a true scorpion. Hence, the name “false scorpion.”

Are they dangerous? Only if you’re tiny prey. Pseudoscorpions range in size from 1 to 8 millimeters, so they’re about the size of a freckle. No one ever got attacked by a freckle, did they?

Just like the majority of other arachnids, they are carnivorous and hunt their prey. Which they’re damn good at.

Pseudoscorpion feeding (Photo Credit: Kristin Hook)

Pseudoscorpion feeding – microscopic view (Photo Credit: Kristin Hook)

Here’s an image I took of a pseudoscorpion holding three prey items – it’s got one springtail on each pedipalp (pincer) and one in its mouthpart! Normally, they pierce their prey using their palps, and then they put the prey up to their mouthpart so they can digest it. Some pseudoscorpions even have venom in their palps that they can infuse into their prey to immobilize it.

With over 3,300 species, they are found practically in every corner of the world except the ocean and Antarctica. You might wonder how such tiny creatures get around on the Earth. The likely answer is a really cool behavior called phoresy. They hitch rides on other animals!


A fly (Leptopeza flavipes) with passenger pseudoscorpion (Lamprochernes sp.) in Cologne, Germany (Wiki Commons)

Now of course, the best part about pseudoscorpion behavior involves their mating habits. They are incredibly diverse in how they transfer sperm to females, but the majority of pseudoscorpions transfer their sperm indirectly. Which means males can fertilize females without ever encountering them!

These males deposit lots of little packets of sperm on a stalk, which look like a little balloon gift.

A pseudoscorpion spermatophore (Photo credit: Kristin Hook)

Females wander around, and if they’re receptive, they pick them up. That’s it. Pretty boring sex, but highly exciting if you’re a researcher! Mostly because these stalks differ in their complexity. The species in which males and females do encounter one another entails much more elaborate spermatophores.

From my short time working with these creatures, I appreciate this: animals can be hard to study, especially in the lab. But nothing is more exciting than going out into the field and successfully finding a critter that is literally more difficult to find than a needle in a haystack. And in another country no less!

From this, I hope you appreciate two things: there is a tiny world among us that is there if you bother to look just below the surface. Also, that taking the time to bother a strange biologist might just lead to a pleasant surprise or two. In our case, it was a pseudoscorpion AND a scorpion under the same rock. Huzzah!