Secret Guardians of the Books

In the episode “Paper Pete” of the animated television series Adventure Time, the boy protagonist, Finn, encounters “the secret guardians of the books in the library.” This band of origami-esque creatures, known as Pagelings and led by Paper Pete, protect the library’s books from being eaten by the Moldos. The Pagelings are engaged in an ongoing war with the Moldos, and fight these book-consuming blobs with paper swords and by transforming into different folded-paper shapes.

Paper Pete (far left) and the other Pagelings. What a crew. Photo credit:

This collection of characters is—like in all episodes of Adventure Time—outlandish and adorable, charming and absurd. But also. Kind of real.

Pseudoscorpions are basically Pagelings in real life. These arachnids frequently live in books, consuming booklice. Booklice are small insects that eat the paste used in the binding of old books, damaging them in a manner similar to the Moldos of Adventure Time. Fights between pseudoscorpions and booklice, however, do not resemble the epic battling of the Pagelings and the Moldos. Their interaction may well be epic, but more of an epic massacre of booklice than an ongoing war. Booklice really don’t stand a chance against pseudoscorpions. But we’ll get to that later.

Pseudoscorpions typically range from 1 to 8 millimeters in length, the largest species being 12 millimeters long. Also known as false scorpions or book scorpions, they do indeed resemble their namesake, though without the scorpion’s infamous stinger/tail combo. Like all arachnids (spiders, scorpions, ticks, etcetera), they posses 8 legs. With teardrop-shaped bodies, a pseudoscorpion may even be mistaken for a tick, save the disproportionately-long pincer appendages protruding from either side of their head. These pincers are known as pedipalps. And they pretty much allow pseudoscorpions as much badassery as possible when you’re less than a centimeter long.

Check out those pedipalps! Gonna mess you up. (Just kidding, harmless to humans.) Photo credit:

What badassery, you ask? Psuedoscorpions are formidable and non-exclusionary predators. They will consume anything small enough, including insect larvae, springtail, mites, and the aforementioned booklice. Pseudoscorpions have terrible eyesight (some species don’t even have eyes), and rely on specialized hair-like structures on their pedipalps to detect airborne vibrations. These hairs, known as trichobothria, are extremely sensitive and afford the pseudoscorpion “sight,” providing an accurate depiction of an individual’s surroundings via minute air vibrations. The trichobothria allow a pseudoscorpion to detect and stalk their prey, initiating a gruesome sequence of events that leads to a small insect’s demise.

A pseudoscorpion first seizes its prey in a pedipalp. To cease futile struggling, the pseudoscorpion injects a paralyzing (but non-lethal) venom into its prey. This venom comes from a gland and duct in the mobile finger of the pseudoscorpion’s pedipalp (the other half of the pedipalp is stationary). The venom is injected into the prey’s body via the pointed tip at the end of the mobile finger. With this venom, the pseudoscorpion’s prey is still alive but no longer able to attempt escape. The pseudoscorpion brings the prey to its mouth and douses it with corrosive saliva, liquefying the victim. And with this, the pseudoscorpion is able to slurp up its undead, squishy-soft dinner. So, as you might guess, wingless booklice are helpless in the face of such ferocity.

Pseudoscorpions aren’t exclusively found in books. There are some 3,300 species of pseudoscorpions worldwide, populating every continent except Antarctica. Most species are found in the tropics, but 200 species are in North America. They prefer areas of high humidity and are often found in leaf littler, moss, the crevices of tree bark, under rocks, and in bird or mammal nests. The house pseudoscorpion, Chelifer cancroides, is the species most likely to be found inside—living in old books, laundry rooms, basements and bathrooms.

So I know what you’re thinking: Why haven’t I noticed these creatures? I live in a house (or something resembling a house). I read books. WHERE ARE THE PSEUDOSCORPIONS?!!!

CALM DOWN. They’re there. You just don’t know it. Pseudoscorpions are described as having a “secretive nature.” This combined with their small size leads to pseudoscorpions remaining mostly unseen by humans despite their pervasiveness. When humans do encounter a pseudoscorpion, they are likely to mistake them for a tick or spider. Luckily, pseudoscorpions, despite the horrors they pose to booklice and the like, are totally harmless to humans and pets. Homeowners actually benefit from the pseudoscorpions lurking invisibly in damp areas of their home, eating small household pests. If you have any old books you can be especially thankful for pseudoscorpions, undoubtedly protecting your dusty volumes of paste-bound pages behind the scenes.

The process by which a pseudoscorpion gets into your house is no pedestrian crawl-through-a-crack method. Pseudoscorpions are not like the spiders waltzing through the space under your door. Or maybe they are, but not always. Because pseudoscorpions are phoretic. This means they use larger animals for transportation, a behavior known as phoresy. This reminds me of the YouTube video “Baby Monkey (Going Backwards On A Pig).” If you haven’t seen this, I recommend you watch it as soon as freaking possible. But I’ll describe it for those of you who live under rocks (much like the pseudoscorpion) or have better things to do than watch videos your friends say will be funny (also much like the pseudoscorpion, who couldn’t be bothered with such matters). In said video, a baby monkey rides backwards on a little pig scurrying around while the singer-songwriter Parry Gripp sings a song about a baby monkey riding backwards on a pig.

Yeah, that was a mildly unnecessary description.

But! Now you have a great idea of how pseudoscorpions get into your house, or just travel from Humid Place #1 to Humid Place #2. They are the baby monkey. And the pig is a beetle or a fly (or any insect large enough) that a pseudoscorpion can hitch a ride on. Phoresy allows pseudoscorpions access not only to the inside of your home and the tasty booklice populating your ancient tomes, but also contributes to how widely distributed they are today. To be so common and so enigmatic is quite a feat for the little pseudoscorpion—maybe if you’re observant enough you’ll get to see one someday. And what an honor that would be, to meet a secret guardian of the books.


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