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Title: Scorpion  
Author: World Heritage Encyclopedia
Language: English
Subject: Chelicerata, Monsuno, Spider, Hadrurus spadix, Toxin
Collection: Arachnids, Living Fossils, Scorpions, Silurian First Appearances
Publisher: World Heritage Encyclopedia


Temporal range: Silurian–Recent
Asian forest scorpion in Khao Yai National Park, Thailand
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Subclass: Dromopoda
Order: Scorpiones
C. L. Koch, 1837

See classification for families.

Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. They have eight legs and are easily recognised by the pair of grasping pedipalps and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. Scorpions range in size from 9 mm (Typhlochactas mitchelli) to 20 cm (Hadogenes troglodytes).[1]

The evolutionary history of scorpions goes back to the Silurian era 430 million years ago. They have adapted to a wide range of environmental conditions and can now be found on all continents except Antarctica. Scorpions number about 1750 described species,[2] with 13 extant families recognised to date. Only about 25 of these species are known to have venom capable of killing a human being.[3]:1The taxonomy has undergone changes and is likely to change further, as genetic studies are bringing forth new information.


  • Etymology 1
  • Geographical distribution 2
  • Classification 3
    • Systematics 3.1
  • Fossil record 4
  • Morphology 5
    • Cephalothorax 5.1
    • Mesosoma 5.2
    • Metasoma 5.3
  • Fluorescence 6
  • Biology 7
    • Reproduction 7.1
    • Birth and development 7.2
  • Relationship with humans 8
    • Sting and venom 8.1
      • First aid 8.1.1
      • Medical use 8.1.2
    • Consumption 8.2
    • In culture 8.3
  • Harvesting 9
  • See also 10
  • References 11
  • External links 12


The word scorpion is thought to have originated in Middle English between 1175 and 1225 AD from Old French scorpion,[4] or from Italian scorpione, both derived from the Latin word scorpius,[5] which is the romanisation of the Greek word σκορπίος – skorpíos.[6]

Geographical distribution

Scorpions are found on all major land masses except Antarctica. Scorpions did not occur naturally in Great Britain, New Zealand and some of the islands in Oceania, but now have been accidentally introduced in some of these places by human trade and commerce.[3]:249 The greatest diversity of scorpions in the Northern Hemisphere is to be found in the subtropical areas lying between latitudes 23° N and 38° N. Above these latitudes, the diversity decreases, with the northernmost occurrence of scorpions being the northern scorpion Paruroctonus boreus at Medicine Hat, Alberta, Canada 50° N.[3]:251

Today, scorpions are found in virtually every terrestrial habitat, including high-elevation mountains, caves and intertidal zones, with the exception of boreal ecosystems, such as the tundra, high-altitude taiga and the permanently snow-clad tops of some mountains.[3]:251–252[7] As regards microhabitats, scorpions may be ground-dwelling, tree-living, lithophilic (rock-loving) or psammophilic (sand-loving); some species, such as Vaejovis janssi, are versatile and found in every type of habitat in Baja California, while others occupy specialised niches such as Euscorpius carpathicus, which occupies the littoral zone of the shore.[8]

Five colonies of scorpions (Euscorpius flavicaudis) have established themselves in Sheerness on the Isle of Sheppey in the United Kingdom.[9] This small population has been resident since the 1860s, having probably arrived with imported fruit from Africa. This scorpion species is small and completely harmless to humans. This marks the northernmost limit where scorpions live in the wild.[10][11]


There are thirteen families and about 1,750 described species and subspecies of scorpions. In addition, there are 111 described taxa of extinct scorpions.[12]

This classification is based on that of Soleglad & Fet (2003),[13] which replaced the older, unpublished classification of Stockwell.[14] Additional taxonomic changes are from papers by Soleglad et al. (2005).[15][16]


The following classification covers extant taxa to the rank of family.

Order Scorpiones

Fossil record

Proscorpius osborni, fossil scorpion initially thought to be a eurypterid

Scorpions have been found in many fossil records, including marine Silurian and estuarine Devonian deposits, coal deposits from the Carboniferous Period and in amber. The oldest known scorpions lived around 430 million years ago in the Silurian period. Though once believed to have lived on the bottom of shallow tropical seas,[17] early scorpions are now believed to have been terrestrial and to have washed into marine settings together with plant matter. These first scorpions were believed to have had gills instead of the present forms' book lungs though this has subsequently been refuted.[18][19][20] The oldest Gondwanan scorpiones (Gondwanascorpio) comprise the earliest known terrestrial animals from Gondwana.[21] Currently, 111 fossil species of scorpion are known.[12] Unusually for arachnids, there are more species of Palaeozoic scorpion than Mesozoic or Cenozoic ones.

The eurypterids, marine creatures that lived during the Paleozoic era, share several physical traits with scorpions and may be closely related to them. Various species of Eurypterida could grow to be anywhere from 10 centimetres (3.9 in) to 2.5 metres (8.2 ft) in length.[22] However, they exhibit anatomical differences marking them off as a group distinct from their Carboniferous and Recent relatives. Despite this, they are commonly referred to as "sea scorpions".[23] Their legs are thought to have been short, thick, tapering and to have ended in a single strong claw; it appears that they were well-adapted for maintaining a secure hold upon rocks or seaweed against the wash of waves, like the legs of a shore crab.


Scorpion anatomy:
1 = Cephalothorax or Prosoma;
2 = Abdomen or Mesosoma;
3 = Tail or Metasoma;
4 = Claws or Pedipalps
5 = Legs;
6 = Mouth parts or Chelicerae;
7 = pincers or Chelae;
8 = Moveable claw or Tarsus;
9 = Fixed claw or Manus;
10 = Sting or Aculeus ;
11 = Telson (follows anus in previous joint).
Front of scorpion
Sting of an Arizona bark scorpion

The body of a scorpion is divided into three parts (tagmata): the head (cephalothorax), the abdomen (mesosoma) and the tail (metasoma).[3]:10


The chelae, commonly called claws or pincers) and four pairs of walking legs. The scorpion's exoskeleton is thick and durable, providing good protection from predators. Scorpions have two eyes on the top of the cephalothorax, and usually two to five pairs of eyes along the front corners of the cephalothorax. The position of the eyes on the cephalothorax depends in part on the hardness or softness of the soil upon which they spend their lives.[24]

The pedipalp is a segmented, chelate (clawed) appendage used for prey immobilisation, defence and sensory purposes. The segments of the pedipalp (from closest to the body outwards) are coxa, trochanter, femur (humerus), patella, tibia (including the fixed claw and the manus) and tarsus (moveable claw).[25] A scorpion has darkened or granular raised linear ridges, called "keels" or carinae on the pedipalp segments and on other parts of the body, which are useful taxonomically.[3]:12


The abdomen, also called the book lungs. The spiracle openings may be slits, circular, elliptical, or oval.[3]:13–15


The metasoma, the scorpion's tail, comprises five caudal segments (the first tail segment looks like a last mesosoman segment) and the sixth bearing the telson (the sting). The telson, in turn, consists of the vesicle, which holds a pair of venom glands, and the hypodermic aculeus, the venom-injecting barb.

On rare occasions, scorpions can be born with two metasomata (tails). Two-tailed scorpions are not a different species, merely a genetic abnormality.[27]


A scorpion under a black light. In normal lighting, this scorpion appears black.

Scorpions are also known to glow when exposed to certain wavelengths of ultraviolet light such as that produced by a black light, due to the presence of fluorescent chemicals in the cuticle. One fluorescent component is now known to be beta-carboline.[28] A hand-held UV lamp has long been a standard tool for nocturnal field surveys of these animals. Fluorescence occurs as a result of sclerotisation and increases in intensity with each successive instar.[28] This fluorescence may have an active role in scorpion light detection.[29]


Scorpions prefer areas where the temperatures range from 20 to 37 °C (68 to 99 °F), but may survive temperatures ranging from well below freezing to desert heat.[30][31] Scorpions of the genus Scorpiops living in high Asian mountains, bothriurid scorpions from Patagonia and small Euscorpius scorpions from Central Europe can all survive winter temperatures of about −25 °C (−13 °F). In Repetek (Turkmenistan), there live seven species of scorpions (of which Pectinibuthus birulai is endemic) in temperatures varying from −31–50 °C (−24–122 °F).[32]

They are nocturnal and fossorial, finding shelter during the day in the relative cool of underground holes or undersides of rocks, and emerging at night to hunt and feed. Scorpions exhibit photophobic behavior, primarily to evade detection by predators such as birds, centipedes, lizards, mice, possums and rats.[33]

Scorpions are opportunistic predators of small arthropods, although the larger kinds have been known to kill small lizards and mice. The large pincers are studded with highly sensitive tactile hairs, and the moment an insect touches these, they use their chelae (pincers) to catch the prey. Depending on the toxicity of their venom and size of their claws, they will then either crush the prey or inject it with neurotoxic venom. This will kill or paralyze the prey so the scorpion can eat it. Scorpions have an unusual style of eating using chelicerae, small claw-like structures that protrude from the mouth that are unique to the Chelicerata among arthropods. The chelicerae, which are very sharp, are used to pull small amounts of food off the prey item for digestion into a pre-oral cavity below the chelicerae and carapace. Scorpions can ingest food only in a liquid form; they have external digestion. The digestive juices from the gut are egested onto the food and the digested food sucked in liquid form. Any solid indigestible matter (fur, exoskeleton, etc.) is trapped by setae in the pre-oral cavity, which is ejected by the scorpion.[3]:296–297

Scorpions can consume huge amounts of food at one sitting. They have a very efficient food storage organ and a very low metabolic rate combined with a relatively inactive lifestyle. This enables scorpions to survive long periods when deprived of food; some are able to survive 6 to 12 months of starvation.[3]:297–298 Scorpions excrete very little; their waste consists mostly of insoluble nitrogenous compounds such as xanthine, guanine and uric acid.[8]


Most scorpions reproduce sexually, and most species have male and female individuals. However, some species, such as Hottentotta hottentotta, Hottentotta caboverdensis, Liocheles australasiae, Tityus columbianus, Tityus metuendus, Tityus serrulatus, Tityus stigmurus, Tityus trivittatus and Tityus urugayensis, reproduce through parthenogenesis, a process in which unfertilised eggs develop into living embryos. Parthenogenic reproduction starts following the scorpion's final moult to maturity and continues thereafter.

Sexual reproduction is accomplished by the transfer of a spermatophore from the male to the female; scorpions possess a complex courtship and mating ritual to effect this transfer. Mating starts with the male and female locating and identifying each other using a mixture of pheromones and vibrational communication. Once they have satisfied the other that they are of opposite sex and of the correct species, mating can commence.

The courtship starts with the male grasping the female's pedipalps with his own; the pair then perform a "dance" called the "promenade à deux". In this "dance," the male leads the female around searching for a suitable place to deposit his spermatophore. The courtship ritual can involve several other behaviours, such as juddering and a cheliceral kiss, in which the male's chelicerae – pincers – grasp the female's in a smaller more intimate version of the male's grasping the female's pedipalps and in some cases injecting a small amount of his venom into her pedipalp or on the edge of her cephalothorax,[34] probably as a means of pacifying the female.

When the male has identified a suitable location, he deposits the spermatophore and then guides the female over it. This allows the spermatophore to enter her genital opercula, which triggers release of the sperm, thus fertilising the female. The mating process can take from 1 to 25+ hours and depends on the ability of the male to find a suitable place to deposit his spermatophore. If mating continues too long, the female may lose interest, ending the process.

Once the mating is complete, the male and female will separate. The male will generally retreat quickly, most likely to avoid being cannibalised by the female, although sexual cannibalism is infrequent with scorpions.

Birth and development

Unlike the majority of species in the class Arachnida, which are oviparous, scorpions seem to be universally ovoviviparous. The young are born one by one after hatching and expelling the embryonic membrane, if any, and the brood is carried about on its mother's back until the young have undergone at least one moult. Before the first moult, scorplings cannot survive naturally without the mother, since they depend on her for protection and to regulate their moisture levels. Especially in species that display more advanced sociability (e.g. Pandinus spp.), the young/mother association can continue for an extended period of time. The size of the litter depends on the species and environmental factors, and can range from two to over a hundred scorplings. The average litter however, consists of around 8 scorplings.[35]

The young generally resemble their parents. Growth is accomplished by periodic shedding of the exoskeleton (ecdysis). A scorpion's developmental progress is measured in instars (how many moults it has undergone). Scorpions typically require between five and seven moults to reach maturity. Moulting commences with a split in the old exoskeleton just below the edge of the carapace (at the front of the prosoma). The scorpion then emerges from this split; the pedipalps and legs are first removed from the old exoskeleton, followed eventually by the metasoma. When it emerges, the scorpion's new exoskeleton is soft, making the scorpion highly vulnerable to attack. The scorpion must constantly stretch while the new exoskeleton hardens to ensure that it can move when the hardening is complete. The process of hardening is called sclerotisation. The new exoskeleton does not fluoresce; as sclerotisation occurs, the fluorescence gradually returns.

Relationship with humans

Sting and venom

All known scorpion species possess venom and use it primarily to kill or paralyze their prey so that it can be eaten. In general, it is fast-acting, allowing for effective prey capture. However, as a general rule they will kill their prey with brute force if they can, as opposed to using venom. It is also used as a defense against predators. The venom is a mixture of compounds (neurotoxins, enzyme inhibitors, etc.) each not only causing a different effect but possibly also targeting a specific animal. Each compound is made and stored in a pair of glandular sacs and is released in a quantity regulated by the scorpion itself. Of the 1,000+ known species of scorpion, only 25 have venom that is deadly to humans; most of those belong to the family Buthidae (including Leiurus quinquestriatus, Hottentotta, Centruroides and Androctonus).[8][36]

First aid

First aid for scorpion stings is generally symptomatic. It includes strong analgesia, either systemic (opiates or paracetamol) or locally applied (such as a cold compress). Hypertensive crises are treated with anxiolytics and vasodilators.[37]

Medical use

The deathstalker has powerful venom.

Short-chain scorpion toxins constitute the largest group of potassium (K+) channel blocking peptides; an important physiological role of the KCNA3 channel, also known as KV1.3, is to help maintain large electrical gradients for the sustained transport of ions such as Ca2+ that controls T lymphocyte (T cell) proliferation. Thus KV1.3 blockers could be potential immunosuppressants for the treatment of autoimmune disorders (such as rheumatoid arthritis, inflammatory bowel disease and multiple sclerosis).[38]

The venom of Uroplectes lineatus is clinically important in dermatology.[39]

Toxins being investigated include:


Eating scorpions in Beijing, China

Fried scorpion is a traditional dish from Shandong, China.[45]

As a part of Chinese medicine, scorpion wine and snake wine are used as analgesic and antidote.

In culture

  • In North Africa and South Asia, the scorpion is a significant animal culturally, appearing as a motif in art, especially in Islamic art in the Middle East.[46] It is perceived both as an embodiment of evil as well as a protective force that counters evil, such as a dervish's powers to combat evil.[46] In another context, the scorpion portrays human sexuality.[46] Scorpions are used in folk medicine in South Asia especially in antidotes for scorpion stings.[46]


The above uses leads to a price of $50,000 for a black scorpion and the equivalent of $39 million for a gallon of venom.[48]

See also


  1. ^ Edward E. Ruppert, Richard S. Fox, Robert D. Barnes (2004). Invertebrate Zoology. Brooks/Cole.  
  2. ^ František Kovařík (2009). "Illustrated catalog of scorpions, Part I" (PDF). Retrieved January 22, 2011. 
  3. ^ a b c d e f g h i j Gary A. Polis (1990). The Biology of Scorpions.  
  4. ^ "Scorpion".  
  5. ^ "Scorpion".  
  6. ^ σκορπιός, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus.
  7. ^ Bernhard A. Huber, Bradley J. Sinclair and K.-H. Lampe (2005). African biodiversity: molecules, organisms, ecosystems. Springer. p. 26.  
  8. ^ a b c Gordon Ramel. "The Earthlife Web: The Scorpions". The Earthlife Web. Retrieved 2010-04-08. 
  9. ^ T. G. Benton (1992). "The ecology of the scorpion Euscorpius flavicaudis in England".  
  10. ^ T. G. Benton (1991). (Scorpiones, Chactidae)"Euscorpius flavicaudis"The life history of (PDF).  
  11. ^ Jan Ove Rein (2000). "Euscorpius flavicaudis". The Scorpion Files.  
  12. ^ a b Jason A. Dunlop; David Penney; O. Erik Tetlie and Lyall I. Anderson (2008). "How many species of fossil arachnids are there".  
  13. ^ Michael E. Soleglad and Victor Fet (2003). "High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni)" (multiple parts).  
  14. ^ Scott A. Stockwell (1989). Revision of the Phylogeny and Higher Classification of Scorpions (Chelicerata). Ph.D. Dissertation, University of California, Berkeley
  15. ^ Michael E. Soleglad; Victor Fet & F. Kovařík (2005). Peters, 1861 (Scorpiones: Scorpionoidea)"Urodacus Birula, 1903 and Heteroscorpion"The systematic position of the scorpion genera .  
  16. ^ V. Fet and E. Soleglad (2005). "Contributions to scorpion systematics. I. On recent changes in high-level taxonomy.".  
  17. ^ Andrew Jeram (June 16, 1990). "When scorpions ruled the world".  
  18. ^ Gerhard Scholtz & Carsten Kamenz (2006). "The book lungs of Scorpiones and Tetrapulmonata (Chelicerata, Arachnida): evidence for homology and a single terrestrialisation event of a common arachnid ancestor". Zoology 109 (1): 2–13.  
  19. ^ Jason A. Dunlop, O. Erik Tetlie & Lorenzo Prendini (2008). "Reinterpretation of the Silurian scorpion Proscorpius osborni (Whitfield): integrating data from Palaeozoic and recent scorpions". Palaeontology 51 (2): 303–320.  
  20. ^ G. Kühl, A. Bergmann, J. Dunlop, R. J. Garwood & J. Rust (2012). "Redescription and palaeobiology of Palaeoscorpius devonicus Lehmann, 1944 from the Lower Devonian Hunsrück Slate of Germany". Palaeontology 55 (4): 775–787.  
  21. ^ R. W. Gess (2013). "The earliest record of terrestrial animals in Gondwana: a scorpion from the Famennian (Late Devonian) Witpoort Formation of South Africa".  
  22. ^ Simon J. Braddy, Markus Poschmann & O. Erik Tetlie (2008). "Giant claw reveals the largest ever arthropod".  
  23. ^ Ben Waggoner. "Eurypterida". Regents of the University of California. Retrieved 2008-06-13. 
  24. ^ "Department of Entomology".  
  25. ^ "WRBU Scorpion Identification". Retrieved 2012-05-03. 
  26. ^ Knowlton ED, Gaffin DD (June, 2011) "Functionally redundant peg sensilla on the scorpion pecten", NCBI.
  27. ^ Steve Prchal. "Pepe the Two Tailed Scorpion". Sonoran Arthropod Studies Institute. Retrieved 2008-06-13. 
  28. ^ a b Shawn J Stachel, Scott A Stockwell and David L Van Vranken (August 1999). "The fluorescence of scorpions and cataractogenesis".  
  29. ^ Douglas D. Gaffinr, Lloyd A. Bumm, Matthew S. Taylor, Nataliya V. Popokina & Shivani Mann (2012). "Scorpion fluorescence and reaction to light".  
  30. ^ Neil F. Hadley (1970). "Hadrurus arizonensis"Water relations of the desert scorpion, .  
  31. ^ K. Hoshino; A. T. V. Moura and H. M. G. De Paula (2006). "Selection of environmental temperature by the yellow scorpion Tityus serrulatus Lutz & Mello, 1922 (Scorpiones, Buthidae)".  
  32. ^ František Kovařík (1998). Štíři [Scorpions] (in Czech). Jihlava: Madagaskar. p. 19.  
  33. ^ "Scorpions". Australian Museum. Archived from the original on 2009-03-02. Retrieved 2008-06-13. 
  34. ^ Cleveland P. Hickman Jr.; Larry S. Roberts, Allan Larson, Helen I'Anson, David Eisenhour (2005-02-01). Integrated Principles of Zoology (13 ed.). McGraw-Hill Science/Engineering/Math. p. 380.  
  35. ^ W. R. Lourenco (2000). "Reproduction in scorpions, with special reference to parthenogenesis". In S. Toft and N. Scharff. European Arachnology. Aarhus University Press. pp. 71–85.  
  36. ^ "ThinkQuest: Poisonous Animals: Scorpions". 2000. Archived from the original on 2005-04-03. Retrieved December 16, 2009. 
  37. ^ Adriaan Hopperus Buma, David G. Burris, Alan Hawley, James M. Ryan & Peter F. Mahoney (2009). "Scorpion sting". Conflict and Catastrophe Medicine: A Practical Guide (2nd ed.). Springer. p. 518.  
  38. ^ K. George Chandy, Heike Wulff, Christine Beeton, Michael Pennington, George A. Gutman & Michael D. Cahalan (May 2004). channels as targets for specific immunomodulation"+"K.  
  39. ^ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1315.  
  40. ^ J. A. DeBin & G. R. Strichartz (1991). "Chloride channel inhibition by the venom of the scorpion Leiurus quinquestriatus".  
  41. ^ Jessy Deshane, Craig C. Garner & Harald Sontheimer (2003). "Chlorotoxin inhibits glioma cell invasion via matrix metalloproteinase-2".  
  42. ^ E. Carlier, S. Geib, M. De Waard, V. Avdonin, T. Hoshi, Z. Fajloun, H. Rochat, J.-M. Sabatier & R. Kharrat (2000). "Effect of maurotoxin, a four disulfide-bridged toxin from the chactoid scorpion Scorpio maurus, on Shaker K+ channels".  
  43. ^ Bin Gao, Patrick Sherman, Lan Luo, John Bowie & Shunyi Zhu (2009). "Structural and functional characterization of two genetically related meucin peptides highlights evolutionary divergence and convergence in antimicrobial peptides". FASEB journal : official publication of the Federation of American Societies for Experimental Biology 23 (4): 1230–1245.  
  44. ^ Bin Gao, Jia Xu, Maria del Carmen Rodriguez, Humberto Lanz-Mendoza, Rosaura Hernández-Rivas, Weihong Du & Shunyi Zhu (2010). "Characterization of two linear cationic antimalarial peptides in the scorpion Mesobuthus eupeus". Biochimie 92 (4): 350–359.  
  45. ^ Matthew Forney (June 11, 2008) Scorpions for Breakfast and Snails for Dinner, New York Times.
  46. ^ a b c d Jürgen Wasim Frembgen (2004). "The scorpion in Muslim folklore" (PDF).  
  47. ^ Allen S. Weiss (1996). "Between the sign of the scorpion and the sign of the cross: L’Age d'or". In Rudolf E. Kuenzli. Dada and Surrealist Film.  
  48. ^ Medina, Daniel A. "A look at Pakistan’s amazingly lucrative scorpion trade".  

External links

  • Holland, Ben (2008). "Scorpion Facts for Researchers and Kids". 
  • Biolumunescence in scorpions
  • Scorpion anatomy
  • Scorpions in Qatar
  • Caring for a Pet Scorpion
  • Bokma, John. "Scorpion detection using UV LEDs". 
  • "Scorpions". and Digital West Media, Inc. 
  • Rehak, Ondrej. "Photogallery – 36 species of scorpions". 
  • Britt, Robert Roy (June 27, 2006). "Scorpion Venom Tested as Brain Cancer Treatment". LiveScience ( 
  • "Pet Scorpion Information and facts | Scorpion Picture Guide". 
  • Cuevas, Moises, MD (2009). "Scorpions in Sayulita". 
  • Scorpions from the Chihuahuan Desert Region of Mexico and the United States
  • CDC – Insects and Scorpions – NIOSH Workplace Safety and Health Topic
  • The Scorpion Hobby
  • Scorpions distribution maps
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