Photo StoryPublished : Nov 11, 2022Updated : Sep 30, 2023
Although minuscule in size, these tenacious carnivores have some nifty tricks up their pincers, from hitchhiking on other creatures to injecting them with venom and holding them in a death grip
Text: Samuel John
Photos: Abhijith APC
Although minuscule in size, these tenacious carnivores have some nifty tricks up their pincers, from hitchhiking on other creatures to injecting them with venom and holding them in a death grip
As someone who works in the natural sciences, one of every two articles I have read or written talks about Earth’s incredible biodiversity. This is understandable, especially when you live in a tropical country like India, where it will likely take an entire lifetime to get to know the diversity of life that inhabits your neighbourhood. In that spirit, I regularly chance upon life forms so enthralling that they instantly trigger my instinct to witter on about Earth’s “mind-boggling diversity”. The latest creature to blow my mind? Pseudoscorpions. They are arachnids with scorpion-like pincers that typically predate on tiny invertebrates like mites and small insects. However, at times they work together to hunt prey many times their size!
For a visual reference, think of a scorpion with no tail. Despite their similarity in appearance to scorpions (Scorpiones), pseudoscorpions belong to an entirely different taxonomical order (Pseudoscorpiones). They are minuscule predators, typically less than 8 mm in length, that use their scorpion-like pincers to hunt and cling to passing insects for transport. These web-slinging micro hunters are found in nearly every corner of the world.
Pseudoscorpions lead secretive lives hidden in crevices, caves. In his book Essays on the Microscope, George Adams writes, “...this insect [pseudoscorpion] was not unknown to Aristotle, who mentions it as being found in books and paper.” Adam’s book from 1787 called the pseudoscorpion a “lobster insect”. The note from Aristotle about pseudoscorpions living amid scrolls also earned them the common name “book scorpions”.
We’ve come a long way since Aristotle and George Adams in our collective knowledge of tiny living things and the instruments we use to investigate them. With access to macro-photography, seasoned natural history observers like Dr Abhijith APC can gleefully follow these tiny predators and document incredible moments from their enigmatic lives. The moments he captured in this series are from around his home and farm outside Mysore city in Karnataka.
With a penchant for hiding in crevices, pseudoscorpions are virtually invisible to any of us not actively looking for them. These tiny predators and their fascinating lives are critical to us ecologically and economically. As obligate (natural) carnivores that feed on arthropods, they help maintain a balanced arthropod population in their ecosystems. As predators that feed on herbivorous insects like the longhorn beetle (Pterolophiasp.) pictured above, they also play a role in agricultural economics. This image shows two tenacious pseudoscorpions hunting an insect over six times their body length! Pseudoscorpions are an excellent reminder of the mind-boggling diversity of life on Earth, and a great example of how each of these incredible lives (no matter the size) is interwoven into the delicate balance of ecosystems.
Pseudoscorpions are arachnids, and like the rest of the arachnid gang (spiders, scorpions, harvestmen etc.), they have eight legs that allow them to scuttle quickly towards prey or away from predators. These eight legs are connected to the body at the cephalothorax (head and thorax fused together). In the images above, it is the dark portion of the body where all the limbs meet; the chunky light-coloured part that forms most of the body is the pseudoscorpion’s abdomen. The cephalothorax is also where the pseudoscorpion’s characteristic pincers connect to its body. The pincers result from evolutionary modification to pedipalps (longish appendages found on all arachnids). For pseudoscorpions, the pedipalp ends with one immobile and one mobile finger (like microscopic chopsticks). These pincers allow the pseudoscorpion to grip prey firmly (2). Another incredible part of the pseudoscorpion is the jaw (chelicerae). One may wonder: Why all the razzmatazz on a tiny mouth? The chelicerae possess spinnerets that extrude silk. The silk is used to create cocoons (3) that act as safe spaces for egg-laying and moulting between life stages. Pseudoscorpions shed their entire exoskeleton (moult) three times before they reach adulthood.
While hunting, pseudoscorpions have another nifty trick up their pincers. The movable “finger” half of the pincer (in most species) contains a venom gland and duct. This allows the tiny predator to incapacitate small prey by injecting them with venom. In addition to their martial arts style pinching abilities and venom, pseudoscorpions often find strength in numbers. They may work together to subdue prey many times their size, like the bee pictured above. Once the prey is subdued, it is usually dragged into a crevice and consumed. In these images, a group of tree-dwelling pseudoscorpions drag a bee into a crevice on the bark of a tree. When the pseudoscorpions are ready to eat, they secrete a digestive fluid onto their prey and slurp up their meal like a nutritious smoothie.
Pseudoscorpions are thought to have a close relationship with ants (myrmecophilous). Although the nature of this relationship remains to be investigated thoroughly, ants are generally thought to be popular prey for them. Despite their individual and collective strength, even dominant species like weaver ants fall prey to pseudoscorpions. In image 1, the pincers of a pseudoscorpion hiding inside a hole grip a weaver ant’s antenna. The death grip on the weaver ant was so strong that the strength of four colony mates (2) was not enough to rescue the ant from becoming lunch. When pseudoscorpions hunt ants out in the open (3), they are exposed to the risk of very quickly becoming prey for the ants! The pseudoscorpion in the third image holding onto an ant is being pursued by another ant from the same colony. (4) The pseudoscorpion quickly mitigates any threat from the ant’s vengeful mates by moving the fight into a tree bark crevice that is too flat for ants to enter easily.
The world of arachnids is filled with amazing stories of dispersal. Spiders, for instance, release long lines of silk that allow them to fly hundreds of kilometres in a process dubbed “ballooning”. Pseudoscorpions have a more grounded way of getting around — they hitchhike. Phoresis is a relationship in which one organism (the commensal) quite literally piggybacks on another organism (the host). Adding to the long list of “Cool things you can do with pincers”, pseudoscorpions cling onto a wide variety of organisms ranging from (1) web-slinging spiders to (3,4) slow-moving caterpillars. They also regularly latch onto flying insects like beetles (2) that can take them across vast distances. Pseudoscorpions have been found to even make transoceanic journeys using this mode of transportation.
is the co-founder of Spiders and the Sea, a social enterprise working towards bridging people and nature - through research, outreach and creative storytelling.
