SCORPIONS
There about 2,500 different species of scorpion in 22 living families, ranging in size from three quarters of an inch to eight inches, with largest monsters coming from India and West Africa. One specimen found in India measured 29.2 centimeters (11.5 inches); one from Sierra Leone measured 22.8 centimeters (9.01 inches). Buthids are the most dangerous scorpions. They are relatively small in size but their venom is very potent. Larger species in the Scorpionidae family look more menacing but generally carry venom that is considerably less toxic. Scorpion taxonomy is being revised to account for 21st-century genomic studies.[Sources: Venomous Animals of the World; John F. Ross, Smithsonian magazine; Paul Zahl, National Geographic, March 1968; Wikipedia]
Scorpion are tough, little beasts. They can survive long period in temperatures below freezing and temperatures above 115̊F, withstand powerful doses of radiation and go years without food. Although most scorpion species live in deserts and tropical areas that is not they the only place they have been found. Some species live in the Pacific Northwest and Canada. Others are found in the Swiss Alps. And other still have been found under snow covered rocks at 4,267 meters (14,000 feet) in the Himalayas, in caves a half a mile below the earth's surface, in crevices of pineapples and even in the sea.
Scorpions can be found in the tropical, subtropical, and warm temperate regions around the world — in deserts, savannas, humid forests, scrub forests and rain forest in Asia, Africa, North and South America and Australia. Many species live in burrows and prefer habitats with either sand or loose soil in which they can make burrows. Most species or not endangered or haven’t been studied enough to make a judgement about their endangered status. On the International Union for Conservation of Nature (IUCN) Red List, most scorpions are listed as Not Evaluated. There are currently two species in the Buthidae family classified as endangered. Habitat destruction and the exotic pet trade are currently the two biggest threats to scorpions [Source: Ryan Wood, Animal Diversity Web (ADW)]
Websites and Resources on Scorpions : Scorpion Files ntnu.no/ub/scorpion-files ; Desert USA desertusa.com ; National Geographic National Geographic ; Scorpion pictures spidy.goliathus.com/english/gallery-scorpions ; Scorpion anatomy ntnu.no/ub/scorpion-files/scorpion_anatomy ; BugGuide bugguide.net ; Amateur Entomologists' Society amentsoc.org ; Smithsonian bug info si.edu/Encyclopedia_SI/nmnh/buginfo Safrinet Manual for Entomology and Arachnology SPC web.archive.org
Websites and Resources on Animals: Animal Diversity Web animaldiversity.org ; BBC Earth bbcearth.com; A-Z-Animals.com a-z-animals.com; Live Science Animals livescience.com; Animal Info animalinfo.org ; Encyclopedia of Life eol.org , a project to create an online reference source for every species; World Wildlife Fund (WWF) worldwildlife.org the world’s largest independent conservation body; National Geographic National Geographic ; ; Endangered Animals (IUCN Red List of Threatened Species) iucnredlist.org ; Biodiversity Heritage Library biodiversitylibrary.org
Scorpion expert: Gary Polis, Vanderbilt University.
RELATED ARTICLES:
SPIDERS: HISTORY, CHARACTERISTCS, SILK, WEBS factsanddetails.com ;
TARANTULAS: CHARACTERISTICS, VENOM, TOXIC HAIRS, EATING. HUNTING factsanddetails.com ;
SPIDERS AND HUMANS: FEAR, VENOMOUS ONES, MISINFORMATION factsanddetails.com ;
INSECTS: CHARACTERISTICS, DIVERSITY, USEFULNESS, THREATENED STATUS factsanddetails.com
Scorpions Taxonomy
Scorpions and spiders are members of the Arachnid class of animals. They have eight legs and a hard exoskeleton and molt like insects. Many species are carnivores that feed primarily on insects. Many produce poisons and have hair on their legs that can detect sounds, sensation, objects and even taste. Members of the Arachnid class of animals emerged about 400 million years ago and are more closely related to horseshoe crabs than insects.
Insects, centipedes, millipedes, arachnids (including spiders and scorpions) and crustaceans belong to the phylum of arthropods. Arthropods account for three fourths of all known animals. All have exoskeletons made of chitin; a body divided into segments and protected by cuticle; jointed legs arranged in pairs; an open circulatory system with organs bathed in a liquid called hemolymph that is pumped around the body by the heart; and a nervous system comprised of paired nerve chords. Insects have three pairs of legs, spiders and scorpions have four, crabs and shrimps have five and centipedes and millipedes have many.
Buthids — fat-tailed scorpions and bark scorpions — is the largest superfamily of scorpions (Buthoidea). It contains around 1,300 species in around 100 genera. Large genera within Buthidae include Ananteris, Centruroides, Compsobuthus, and Tityus but a high number of species-poor or monotypic genera also exist. They occur in the warmer parts of every major landmass on Earth, except on New Zealand. [Source: Wikipedia, Google AI]
The Scorpionidae family — burrowing and pale-legged scorpions — includes 21 genera, 311 species, and four subfamilies. Morphologically, they are similar to other buthids and other members of the order Scorpiones and includes the largest species of scorpion — the giant forest scorpion (Heterometrus swammerdami) — which reaches lengths of 23 centimeters and weighs up to 56 grams. The largest scorpion ever found was a giant forest scorpion found during the Second World War in the village of Krishnarajapuram, India. It measured 29.2 centimeters (11.5 inches) from the tips of their 'pincers' to the end of the sting according to the Guinness Book of World Records Scorpionidae also includes one of the most well known species, Pandinus imperator, or the emperor scorpion. The most defining characteristics of species in the Scorpionidae are their powerful, broad pincers, which are modified pedipalps (appendages on the front of arachnids), and their segmented curved telson (tail) with a venomous stinger on the end. The emperor scorpion and members of the genus Heterometrus are popular in the pet trade due to their large size. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpions and History
Scorpion are the world's oldest surviving land animal. They evolved from meter-long, scorpion-like creatures that emerged from the sea 350 million years ago and have remained virtually unchanged for the last 100 million years (a 30 million specimen preserved in a piece of amber looks exactly like modern scorpions). In 2013 a 350 million year old scorpion fossil was found in South Africa. It is regarded as the oldest known land animal to live on the supercontinent Gondwana. [Source: Ryan Wood, Animal Diversity Web]
People have long been fascinated by scorpions — a Zodiac sign was named in honor of one — but not endeared by them. In the first century A.D., Pliny the Elder wrote: "They are a horrible plague, poisonous like snakes, except they inflict a worse torture by dispatching their victims with a lingering death lasting three days...Their tail is always engaged in striking and does not stop practicing at any moment, lest it should miss an opportunity.”The Bible referred to scorpions as one of most evil pestilence and in Persian mythology, a scorpion played a role similar to that of the snake in the Garden of Eden, by sting the testicle of a sacred bull whose blood was to supposed to fertilize the universe.
Jeholia longchengi, a species of scorpion that was about 10 centimeters (4 inches) long. lived in China 125 million years ago. Skyler Ware wrote in Live Science: The venomous scorpion was larger than many ancient — and modern — scorpion species. Researchers believe it would’ve been a key species in the food chain, gobbling up spiders, lizards and even small mammals that lived in its ancient ecosystem. It is just the fourth terrestrial scorpion fossil to be found in China and the first Mesozoic-era scorpion fossil found in the country, researchers reported January 24, 2025 in the journal Science Bulletin. [Source: Skyler Ware, Live Science, March 5, 2025]
“Most scorpions from the Mesozoic era (252 million to 66 million years ago) are preserved in amber. Fossilized scorpions are much rarer because these arachnids live under rocks and branches, where they're less likely to be trapped in sediment and fossilize, said study co-author Diying Huang, a researcher at the Nanjing Institute of Geology and Palaeontology in China. The scientists found the fossil in the Yixian Formation, a hotbed of Early Cretaceous fossils in northeastern China. The team named the new species Jeholia longchengi. "Jeholia" refers to the Jehol Biota, the ecosystem of northeast China in the Early Cretaceous about 133 million to 120 million years ago, and "longchengi" refers to the Longcheng district of Chaoyang, China, where the fossil currently resides. J. longchengi was roughly 4 inches (10 centimeters) long, making it something of a giant of its time. "Other Mesozoic scorpions are much smaller, most of them less than half [the size] of the new species," Huang told Live Science.
J. longchengi has a pentagonal body and rounded spiracles, which are the openings in its body that allowed it to breathe. These characteristics are similar to those found in some families of modern-day scorpions that inhabit other parts of Asia. But unlike those families, J. longchengi has fairly long legs and slim pedipalps, or pincers, that lack spurs along a segment called the patella. Fossils of many other animals — including dinosaurs, birds, mammals and insects — have been found in the Jehol Biota, suggesting a complex food web. Larger mammals and dinosaurs may have preyed upon J. longchengi, while the scorpion's diet may have included insects, spiders, frogs and even small lizards or mammals, the researchers wrote in the study.
Scorpion Characteristics
Scorpions have eight legs and pinchers like crabs, called pedipalps. Their venom is released from a claw-like stinger on the creatures tail, which actually isn't a tail but an extension of its abdomen called a metasoma. A scorpion’s body consists of two main segments, the prosoma and the opisthosoma, with the prosoma being covered by a carapace. Chelicerae are the appendages closest to the mouth. They are used to pull small bits of food towards the mouth. The pedipalps — the claws or pincers — are used to capture and tear prey apart. Scorpions periodically molt their armorlike exoskeleton which covers the prosoma and opisthosoma and is made of chitin, the same material in crab, lobster, shrimp and insect exoskeletons are made of.
Scorpions are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature). Sexual Dimorphism (differences between males and females) is not present: Both sexes are roughly equal in size and look similar. It is difficult to distinguish them. Lifespan varies by species but typically ranges between five to eight years in captivity, and potentially longer in the wild. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpionidae scorpions are typically identified by their large size, heavy body, broad pedipalps with short fingers, short metasoma and short, stout legs. Two centrally located eyes sit on top of the carapace along with lateral eyes on the sides. Their massive pincers and the pentagon-shaped sternum are the easiest way to distinguish the Scorpionidae from the sister taxa Buthidea. The opisthosoma consists of 13 segments which are separated into the mesosoma and metasoma. The mesosoma consists of seven segments while the metasoma has five segment and ends with the venomous stinger. Scorpionidae contains some of the world's largest scorpions, including Heterometrus (Gigantometrus) swammerdami mentioned above. Pandinus imperator can reach between 18 and 20 centimeters. Opistophthalmus gigas measure up to 16 centimeters.[Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpions give off natural fluorescence under ultra-violet light, This means they glow vivid-blue green in the dark when exposed to a black light, which is how scientists often find them. The fluorescence comes from chemicals — the fluorophores β-carboline and 4-methyl-7-hydroxycoumarin — concentrated in the outermost layer of scorpion's exoskeleton cuticle. The function of this fluorescence is not known. Hypotheses include sun protection, finding mates in the dark, predator avoidance, prey attraction and regulating metabolism. Not all scorpions give off natural fluorescence but many do.
Scorpion Senses and Venom
Scorpions sense and communicate with touch and chemicals usually detected by smelling. They also use vibrations to communicate. Scorpions have anywhere from two to 12 eyes yet are virtually blind. They can make out the difference between white and dark, but they can’t "see" an object. Their sense of touch is their most important and developed sense. Like spiders they have hair on the legs that can detect sounds, sensation, objects and even taste.
Scorpionidae have two large eyes on the top of their heads and up to five pairs of eyes on the sides of their carapace, yet they still have poor eye sight. It has been shown that scorpions eyes are most sensitive to green and UV light. Hearing is done by picking up vibrations in the ground through the tarsal regions of their front legs. Scorpions are solitary so communication between them is minimal. They may use pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species) to attract mates.
Scorpions sometimes use their toxin to immobilize prey but it is primarily a means of defense. Venom is produced in a pair of venom glands that are located near the stinger at the end of the “tail.” Generally a scorpion stings its victim by arching the "tail" over the back of the abdomen and making the strike in front its body. The levels of toxicity in the venom varies quite a bit. The most dangerous scorpions are found in Mexico, India, the Middle East and southern African countries such as Namibia. The most venomous scorpion is the Palestine yellow scorpion. Ranging across North Africa and the Middle East, it fortunately only delivers small amounts of poison.
Scorpion Behavior and Defenses
Scorpions are fossorial (engaged in a burrowing life-style or behavior, and good at digging or burrowing), nocturnal (active at night), motile (move around as opposed to being stationary), sedentary (remain in the same area) and solitary. Scorpions usually only come out at night. Their days are spent under rocks or in cracks or in burrows. They seek out dark places which is why they sometimes into shoes. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Many species live in burrows and prefer habitats with either sand or loose soil in which they can make burrowws. Most of the daylight is spent either in their burrow or under rocks or logs. The constructed burrows can be up to a meter long and help to keep them cool during the day. The only time males leave their burrows for extended periods of time in to find mates. Some species spend 92 percent to 97 percent of their lives in corkscrew-shaped burrows.
Natural predators of scorpions include various birds, mammals, spiders, lizards, bats, and even centipedes, monkeys and baboons. Some species of owls sweep down out of the sky, bite off the scorpion's stinger and then consumes the rest of it. Defense against prey depends on what their strongest defense is. Scorpions with strong pincers will use their pincers while scorpions with strong venom use their stinger. The use of the venomous stinger depends on the maturity of the scorpion, with young stinging prey two to three times and adults using only their pedipalps.
Scorpions on the defense usually flick up their stingers and then make a quick dash for cover. Sometimes they rise on their legs and swivel like a tank turret and then quickly dig themselves into the sand. They often travel in pairs so if you find one scorpion there is probably another lurking around somewhere close.
Scorpion Feeding Behavior and Hunting
Scorpions are mainly nocturnal, ambush predators, who sit and wait for prey, often in inside or located just outside their burrow. Some are active hunters away that venture from their burrows in search of prey. It is believed that scorpions mainly use senses other than hearing or sight to locate prey. The location of prey is determined by either the tarsal organs (sensory pits on the dorsal surface of the tarsus (claw) that help them detect vibrations and other stimuli). or by long thin sensory hairs on the pedipalps, known as trichobothria.
Scorpions are primarily insectivores (eat insects) and carnivores (eat meat or animal parts). They feed on worms, centipedes, grasshoppers, flies, beetles, cockroaches, crickets, moths, spiders, wasps, small lizards, smaller scorpions, and small mammals.
Many species locate their prey by picking up their vibrations on the ground. The large scorpionids often dig to locate prey such as spiders, lizards and even small mammals. Scorpions attempt to subdue their prey mechanically with their pincers, saving their stingers only for a last resort because it sometimes it a week or more to generate a new venom supply. Prey is eaten with pincer-like appendages near their mouth that break the prey into little pieces before inserting their mouth.
According to Animal Diversity Web: Juveniles use their venomous stinger to capture prey while adults use their pincers to crush and rip apart their prey. Usually the scorpion will grasp the prey at either end, thereby obtaining a head grip with one pedipalp that is frequently lethal when force is applied. Prey is often passed from pedipalp to pedipalp in order to find an the most effective grip. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpion Reproduction
Scorpions are monogamous (have one mate at a time) and viviparous (give birth to live young that developed in the body of the mother) unlike other arthropods, which lay eggs. Reproduction for scorpions is external, meaning the male’s sperm fertilizes the female’s egg outside her body. They engage in seasonal breeding, with the mating seasonal depending on the climate. Species in temperate regions mate during the summer or spring, and those in tropical regions mate during the rainy season. Seven to nine months after fertilization, females give birth to up to 100 offspring. Females are able to reproduce between a few months and one year since their last mating. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpion males locate females by sweeping "toothed" leglike structures called pectines over the ground to detect pheromones given off by females that indicate when they are ready to mate. When males sense these pheromones they often start shaking wildly in a motion scientists have dubbed "juddering."
Like praying mantis and some spiders, female scorpions often kill the males after mating is over by injecting them with a series of lethal stings. In many cases the female will then devour the male. Even before mating begin, females sometimes view they male as prey. When a male approaches a female he does so with trepidation and often grabs her pincers before he does anything else.
Scorpion Mating
Ryan Wood of Animal Diversity Web wrote: Mating involves three phases, with the first being the introductory phase. Courtship begins with the female’s pedipalps, chelae or other segments being gripped by the male’s pedipalps. After gripping, the female typically attempts to push the male away with her metasoma, often by trying to sting. Often times the male will use his own metasoma as a club in an attempt to protects itself from stinging. Once the grip is released, the female walks towards the male and starts to rock her body forward and back, with the male then repeating the motion. The female will then start to grab him using her own pedipalps. [Source: Ryan Wood, Animal Diversity Web (ADW)]
After the second grip the male will began his walk leading into the second phase which is known as the promenade phase. The male walks backwards with the female following. They then engage in a chelicerae grip and walk a short distance, during which the male will clear a spot for the spermatophore deposition. Once a suitable spot is found, the male swill lower its mesosoma in order to deposit the spermatophore. The male will then move his prosoma back and forth until the sticky basal plate makes contact with the surface of substrate (Jiao 2009). The male then pulls the female over the spermatophore in order to initiate sperm transfer. (Jiao and Zhu, 2009)
During sex, the male and female jerk and dance around, sometimes with their tails intertwined, with the male holding the female in his pincers. The a male scorpion ejaculates on the ground and pulls the female so her sex organ touches the sperm. After she takes in the sperm the couple usually disengage and go their separate ways.
Describing the mating habits of scorpions, the famous 19th century French naturalist Jean Henri Fabre wrote: "One of either sex, face each other with claws outstretched and fingers clasped. Their tails prettily curled, the couple stroll with measured steps. The male is ahead and walks backwards; the female follows obediently, slashed by here finger tips and face to face with her leader. At times the male turns gracefully to right or left and places himself side by side with his companion. Then for a moment with his tail laid flat, he strokes her spine. She stands motionless, impassive."
Fabre wrote, "For over an hour I watch, and then something happens. The male has found a shelter to his liking. he releases his companion with one hand, and, continuing to hold her with the other he scratches out with legs and tail a shallow opening in the sand....He enters and slowly, without violence, drags partner after. A plug of sand closes the dwelling. The couple are at home."
Scorpion Offspring and Cannibalism
Scorpion young are precocial. This means they are relatively well-developed when born. Parental care is provided by females. Young are born alive and are miniature versions of adults except they have weak exoskeleton. After the young are born they crawl onto the backs of their mothers, where they remain until they have undergone their first molt, between 30 and 50 days, and their exoskeleton has become hard enough for them to survive on their own. The young will go through five different molts before they reach full development. [Source: Ryan Wood, Animal Diversity Web (ADW)]
Scorpion babies are soft and vulnerable and sometimes look like little potato bugs. In some cases, the mother will resort to cannibalism of her young if she is unable to find food. Scorpions often feast on other scorpions and eat their own mates and offspring. Biologist believed that scorpions developed this trait to survive under severe condition when they would most likely starve if they didn't eat other. They also say this trait has allowed scorpions to survive as long as they have.
Cannibalism among scorpions of the same species is so widespread that young scorpions often feed and move around at different times and in different places than their elders to avoid being eaten. Scorpions are particularly vulnerable to attacks after the molt and they lack the body armor to fend off attacks.
Scorpions and People
Scorpions like warm, dark places. Sometimes they hide in garages or piles of things or crawl into shoes, clothes or bed lining. They are hard to keep out of house. People who live in places with scorpions are advised to wear shoes at all times and and not blindly reach in dark spaces. They should also check their shoes and clothes before they put them on...or better yet, carefully shake their clothes and shoes before they put them on.
Scorpions are mainly active at night. Scorpion researchers locate scorpions at night with black lights connected to motorcycle batteries stored in their backpacks. Half the known species of scorpion were discovered after scorpion's ability to fluoresce under ultra-violent light was discovered in the 1960s. Newcomers to this kind of search are often surprised by the number of scorpions that materialize in places where it seemed like there were no scorpions. First-rate scorpion collectors can snag 75 individuals an hour.
Bites from scorpions are often painful but rarely dangerous although some species can be dangerous. There are antivenoms for scorpions but they are not always available. If you are really concerned you may want to bring scorpion anti-venom for scorpions you might encounter. These sometimes need to refrigerated. Scorpions are milked to make antivenin by squeezing the venom glands with tweezers and giving the scorpion an electric shock which causes the gland to contract and empty its venom.
The emperor scorpion is indigenous to West Africa. It is very large (up to 30 centimeters in length) and is less venomous than other scorpion species. It is a popular pet as it is also easy to raise, and sells for between $20 and $50 at pet shops.
Human Scorpion Victims
Some scorpion poisons are 100,000 more powerful than cyanide. What saves human victims is the dose of poison are relatively small and stings are often less severe than a bee sting. Symptoms from a scorpion sting include severe pain spreading from the wound, numbness, severe emotional agitation, cramps. Severe reactions include vomiting, diarrhea, respiratory failure. If stung victims are advised to wash the wound with soap, place ice on it and take aspirin or acetaminophen. As is the case with poisonous snakes, wounds from highly toxic scorpions can be treated with antivenin.
Scorpion toxin is a powerful nerve poison, which explains why victim often feel like they have been jolted by an electric shock when they get stung. Often after the initial jolt a burning sensation spreads from the point of the sting, followed by numbness and tingling, which sometimes lasts for several days. Severe stings result in muscles cramps, convulsions, feeling of depression and deep anguish, excessive salivation, perspiration, bulging eyes, dramatic blood pressure rises, and increased and erratic heart beat. Death can occur in minutes or up to 30 hours later often from acute respiratory distress. In some causes the victim seems fine and then experience a violent relapse.
In 1977, I got stung by two scorpions in two nights in the Bahamas of all places. I was with some university friends and we were sleeping on the beach on the island of Exuma. The first time, I came back to our camp from a New Year’s Eve party and stuck my hand in my backpack to get a flashlight and then felt this intense, searing pain that was incredibly strong at first and endured at this really painful stage for 15 minutes to half an hour and then slowly subsided. I didn’t know what stung me or bit me as I was trying to get a flashlight and eventually went to sleep. The next morning I saw a small scorpion in my backpack and presumed that was the culprit. By that time I was alright. The second time, the next night, I woke up with the same searing pain and squeezed and killed a scorpion that had crawled into my shirt and into my sleeping bag that was on the beach. The scorpions were only about five centimeters in long, including their tails. When I was a kid growing up in the Mojave desert I was told scorpions always came in pairs so if you see one there is probably another lurking nearby.
In 2002, Reuters reported: Creepy creatures approach women in bars all the time, but a Swiss woman was shocked to discover an African scorpion had stabbed her hand in a pub near Zurich, early Wednesday, police said. Police were still scratching their heads over how the 3-cm (one-inch) scorpion got into the pub in a Zurich suburb. It remained in the custody of a police reptile expert. The 31-year-old victim was rushed to the hospital by ambulance with sharp pain and swelling in her arm. She remained in hospital Wednesday. [Source: Reuters, May 9, 2002]
Only 25 of the 1,500 species of scorpions deliver potentially lethal stings. Still, thousands of people are killed worldwide by scorpions, more than any other animals save snakes and bees. Most victims are children under five. Many deaths occur in India where 60 percent of the victims are killed by a particularly lethal species.
Describing a death from a scorpion sting, the zoologist J.L. Cloudsley-Thompson wrote, "First, a feeling of tightness develops in the throat so that the victim tries to clear his throat of an imaginary phlegm...The victims next becomes restless and there may be slight, involuntary twitching of the muscles...Convulsion follow, the arms are flailed about and the extremities become quite blue before death occurs."
Medicinal Properties of Scorpion Venom
The venom of some scorpions is used for different medical purposes. Scorpine is a peptide found in the venom of Pandinus imperator and is believed to have anti-malarial and anti-bacterial benefits. Unique in that it is about double the size of other peptides, Scorpine is thought to be hybrid of the peptides cecropin (mall proteins anywhere from 31 - 37 amino acids long and are active against both gram-positive and gram-negative bacteria) and defensin (small proteins that are part of the innate immune system and help defend against microorganisms in animals, plants, and fungi), with some stretches of the sequence showing identical amino acids.[Source: Ryan Wood, Animal Diversity Web (ADW)]
Jennifer S. Holland wrote in National Geographic: “Michael decided to go for a swim. He was on vacation with his family in Guerrero, Mexico, and it was hotter than blazes. He grabbed his swimming trunks from where they’d been drying on a chair, slid them on, and jumped into the pool. Instead of cool relief, a burning pain ripped through the back of his thigh. Tearing off his trunks, he leaped naked from the pool, his leg on fire. Behind him a small, ugly, yellow creature was treading water. He scooped it into a Tupperware container, and the caretaker of the house rushed him to the local Red Cross facility, where doctors immediately identified his attacker: a bark scorpion, Centruroides sculpturatus, one of the most venomous species in North America. The fierce pain from a sting is typically followed by what feels like electric shocks racking the body. Occasionally victims die. Luckily for Michael, the bark scorpion is common in the area, and antivenom was readily available. He had an injection and was released a few hours later. In about 30 hours the pain was gone. [Source: Jennifer S. Holland, National Geographic, February 2013]
“What happened next could not have been predicted. For eight years Michael had endured a condition called ankylosing spondylitis, a chronic autoimmune disease of the skeleton, a sort of spinal arthritis. No one knows what triggers it. In the worst cases the spine may fuse, leaving the patient forever stooped and in anguish. “My back hurt every morning, and during bad flare-ups it was so horrible I couldn’t even walk,” he says. But days after the scorpion sting, the pain went away, and now, two years later, he remains essentially pain free and off most of his medications. As a doctor himself, Michael is cautious about overstating the role of the scorpion’s venom in his remission. Still, he says, “if my pain came back, I’d let that scorpion sting me again.”
“Meanwhile, a neurotoxin from the venom of the giant deathstalker scorpion has been found to attach to the surface of brain cancer cells. The overwhelming reason tumors come back is that surgeons can’t reliably distinguish good cells from bad at the growths’ edges. Magnetic resonance imaging — the best available diagnostic tool — doesn’t detect masses smaller than about a billion cells. This means surgeons have to find the boundaries between tumors and healthy tissue “purely by visual and textural cues,” says James Olson of the Fred Hutchinson Cancer Research Center in Seattle, Washington. “It’s a very imperfect science. Glioma cells weave into normal tissue, and pieces sometimes get left behind.”
“Doctors who treat glioma, the most common form of brain cancer, created a “molecular flashlight” by marking chlorotoxin with a near-infrared dye. On the very first trial, Olson says, the “tumor paint,” as he calls the scorpion-derived marker, “lit up the cancer beautifully. We were literally jumping up and down because we knew what incredible potential this had.” The paint reveals masses with as few as 200 tumor cells. “You can truly see the tumor almost cell by cell,” Olson says. “This will let surgeons get more cancer out, maybe even 100 percent.” Human trials on the dyed toxin will start later this year, and if tests go well, the paint could be used for prostate, colorectal, lung, breast, pancreatic, and skin cancers, as well as glioma, potentially saving or prolonging millions of lives every year.
“No drugs based on scorpion toxins have yet been approved, but these toxins represent a versatile chemical arsenal. One may be a cancer foe, others the basis of cardiac, painkilling, anti-seizure, and antimalarial drugs. There’s even a possible pesticide among them.
Image Sources: Wikimedia Commons
Text Sources: Mostly National Geographic articles. Also David Attenborough books (Princeton University Press), New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, and various books and other publications.
Last updated April 2025