Scorpion

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A scorpion is an arthropod with eight legs, belonging to the order Scorpiones in the class Arachnida. This class also contains the spiders, harvestmen, mites, and ticks. There are approximately 2000 species of scorpions. They are found widely distributed south of 49° N, except New Zealand and Antarctica.

[edit] Physical characteristics

The body of a scorpion is divided into two segments: the cephalothorax (also called the prosoma) and the abdomen/opisthosoma. The abdomen consists of the mesosoma and the metasoma.

Cephalothorax/prosoma: the scorpion's “head”, comprising the carapace, eyes, chelicerae (mouth parts), pedipalps (claw) and the three to four pairs of walking legs.

Mesosoma: the abdomen's front half, is made up of six segments. The first segment contains the sexual organs as well as a pair of vestigial and modified appendages forming a structure called the genital operculum. The second segment bears a pair of featherlike sensory organs known as the pectines; the final four segments each contain a pair of book lungs. The mesosoma is armored with chitinous plates, known as tergites on the upper surface and sternites on the lower surface.

Metasoma: the scorpion's tail, comprising six segments (the first tail segment looks like a last mesosoman segment), the last containing the scorpion's anus and 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.

Cuticle: this makes a tough armor around the body. In some places it is covered with hairs that act like balance organs. An outer layer that makes them fluorescent green under ultraviolet light is called the hyaline layer. Newly molted scorpions do not glow until after their cuticle has hardened. The fluoresent hyaline layer can be intact in fossil rocks that are hundreds of millions of years old.

On rare occasions, scorpions can be born with two metasomata (tails). Two-tailed scorpions are not a different species, but rather a genetic abnormality.^[1]

[edit] Scorpion venom

All scorpion species possess venom. In general, scorpion venom is described as neurotoxic in nature. One exception to this however is Hemiscorpius lepturus which possesses cytotoxic venom. The neurotoxins consist of a variety of small proteins as well as sodium and potassium cations, which serve to interfere with neurotransmission in the victim. Scorpions use their venom to kill or paralyze their prey so that it can be eaten; in general it is fast acting, allowing for effective prey capture.

Scorpion venoms are optimized for action upon other arthropods and therefore most scorpions are relatively harmless to humans; stings produce only local effects (such as pain, numbness or swelling). A few scorpion species, however, mostly in the family Buthidae, can be dangerous to humans. Among the most dangerous are Leiurus quinquestriatus, otherwise dubiously known as the deathstalker, which has the most potent venom in the family, and members of the genera Parabuthus, Tityus, Centruroides, and especially Androctonus, which also have powerful venom. The scorpion which is responsible for the most human deaths is the Androctonus australis, or yellow fat-tailed scorpion of North Africa. The toxicity of A. australis's venom is roughly half that of L. quinquestriatus, but despite the common misconception A. australis does not inject noticeably more venom into its prey. The higher death count is simply due to its being found more commonly, especially near humans. Human deaths normally occur in the young, elderly, or infirm; scorpions are generally unable to deliver enough venom to kill healthy adults. Some people, however, may be allergic to the venom of some species. Depending on the severity of the allergy, the scorpion's sting may cause anaphylaxis and death. A primary symptom of a scorpion sting is numbing at the injection site, sometimes lasting for several days. Scorpions are generally harmless and timid, and only voluntarily use their sting for killing prey, defending themselves or in territorial disputes with other scorpions. Generally, they will run from danger or remain still.

Scorpions are able to regulate how much venom is injected with each sting using striated muscles in the stinger, the usual amount being between 0.1 and 0.6 mg. There is also evidence to suggest that scorpions restrict the use of their venom using it only to subdue large prey, or prey that struggles. It has been found that scorpions have two types of venom: a translucent, weaker venom designed to stun only, and an opaque, more potent venom designed to kill heavier threats. This is likely because it is expensive in terms of energy for a scorpion to produce venom, and because it may take several days for a scorpion to replenish its venom supply once it has been exhausted.^[2][3]

There is currently no equivalent of the Schmidt Sting Pain Index because nobody has yet classified the levels of pain inflicted by different scorpion stings. This is probably because of the risk involved with some species eg Androctonus or Leiurus. However, envenomation by a mildly poisonous species like Pandinus imperator is similar to a bee sting in terms of the pain and swelling that results. A sting on the thumb from a relatively non-dangerous scorpion often feels like the victim has accidentally struck their thumb with a hammer whilst driving in a nail. A sting from a truly dangerous scorpion can feel much worse, as though the victim had hammered a nail right through their thumb. In all cases, application of an ice-pack to the afflicted area helps to relieve the pain. It should be noted that the physical effects of a sting from a medically significant scorpion are not limited to the pain inflicted: there can be bradycardia, tachycardia or in severe cases pulmonary edema.

The stings of North American scorpions are rarely serious and usually result in pain, minimal swelling, tenderness, and warmth at the sting site. However, the bark scorpion (Centruroides exilicauda or sculpturatus), which is found in Arizona and New Mexico and on the California side of the Colorado River, has a much more toxic sting. The sting is painful, sometimes causing numbness or tingling in the area around the sting. Serious symptoms are more common in children and include abnormal head, eye, and neck movements; increased saliva production; sweating; and restlessness. Some people develop severe involuntary twitching and jerking of muscles. Breathing difficulties may occur. The stings of most North American scorpions require no special treatment. Placing an ice cube on the wound reduces pain, as does an ointment containing a combination of an antihistamine, an analgesic, and a corticosteroid. Centruroides stings that result in serious symptoms may require the use of sedatives, such as midazolam, given intravenously. Centruroides antivenom rapidly relieves symptoms, but it may cause a serious allergic reaction or serum sickness. The antivenom is available only in Arizona.

[edit] Reproduction

Most scorpions reproduce sexually and most species have male and female individuals. While the majority of scorpion species reproduce sexually, some, such as Hottentotta hottentotta, Liocheles australasiae, Tityus columbianus, Tityus metuendus, Tityus serrulatus, Tityus stigmurus, Tityus trivittatus, and Tityus urugayensis, all reproduce through parthenogenesis, a process in which unfertilized eggs develop into living embryos. Parthenogenic reproduction starts following the scorpions final molt 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 each 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 performs a "dance" called the "promenade à deux". In reality this is the male leading 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--clawlike mouthparts--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,^[4] probably as a means of pacifying the female.

When he 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 fertilizing 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 goes on for too long, the female may eventually break off the process.

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

[edit] Birth and development

Unlike the majority of Arachnida species, scorpions are viviparous. The young are born one by one, 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, depending on her for protection and to regulate their moisture levels. Especially in species which 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 100+ scorplings.^[5]

The young generally resemble their parents. Growth is accomplished by periodical 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 is effected by means of a split in the old exoskeleton which takes place 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 sclerotization. The new exoskeleton does not fluoresce; as sclerotization occurs, the fluorescence gradually returns.

[edit] Life and habits

Scorpions have quite variable lifespans and the actual lifespan of most species is not known. The age range appears to be approximately 4-25 years (25 years being the maximum reported life span in the species H. arizonensis).

Scorpions prefer to live in areas where the temperatures range from 20°C to 37°C (68°F to 99°F), but may survive in the temperature range of 14°C to 45°C (57°F to 113°F).^[6]

They are nocturnal and fossorial, finding shelter during the day in the relative cool of underground holes or undersides of rocks and coming out at night to hunt and feed. Scorpions exhibit photophobic behavior, primarily to evade destruction by their predators such as birds, centipedes, lizards, mice, possums, and rats.^[7]

Scorpions are opportunistic predators of small arthropods and insects. They use their chela (pincers) to catch the prey initially. 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 a quite unique style of eating which uses chelicerae. These are small claw like structures which protrude from the mouth, only a handful of other animals have these, including spiders and vinegaroons. Chelicerae are very sharp and are used to pull small amounts of food off the prey item for digestion. Scorpions can only digest food in a liquid form; any solid matter (fur, exoskeleton, etc) is disposed of by the scorpion.

[edit] Fossil record

Scorpions have been found in many fossil records, including coal deposits from the Carboniferous Period and in marine Silurian deposits. They are thought to have existed in some form since about 425–450 million years ago. They are believed to have an oceanic origin, with gills and a claw-like appendage that enabled them to hold onto rocky shores or seaweed.

The eurypterids, marine creatures which lived during the Paleozoic era, share several physical traits with scorpions and are closely related to it. Various species of Eurypterida could grow to be anywhere from 10 cm (4 in) to 3 m (9.75 ft) in length. However, they exhibit anatomical differences marking them off as a group distinct from their Carboniferous and recent descendants. Despite this, some refer to them as "sea scorpions."^[8] 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 shore-crab.

[edit] Geographical distribution

Scorpions are almost universally distributed south of 49° N, and their geographical distribution shows in many particulars a close and interesting correspondence with that of the mammals, including their entire absence from New Zealand. The facts of their distribution are in keeping with the hypothesis that the order originated in the northern hemisphere and migrated southwards into the southern continent at various epochs, their absence from the countries to the north of the above-mentioned latitudes being due, no doubt, to the comparatively recent glaciation of those areas. When they reached Africa, Madagascar was part of that continent; but their arrival in Australia was subsequent to the separation of New Zealand from the Austro-Malayan area to the north of it.

In conformity with their wide dispersal, scorpions have become adapted to diverse conditions of existence, some thriving in rainforests, others on open plains, others in sandy deserts and a few even at high altitudes where the ground is covered with snow throughout the winter. In the tropics, they aestivate at times of drought; and in the Alps, they pass the cold months of the year in a state of hibernation.

In the United States, scorpions are most common in southern Arizona and in a swath of land extending through central Texas and central Oklahoma. The common striped scorpion, Centruroides vittatus, reaches from northwest Mexico to southern Colorado, Kansas, southern Missouri, and Mississippi and Louisiana. Species of the genus Vaejovis are found from Florida north to Maryland, the Carolinas, and Tennessee, and as far west as Oregon and California. Paruroctonus boreus is found through the Northwest U.S. and into Canada (Southern Saskatchewan, Southern Alberta and the Okanagan Valley of British Columbia). Scorpions can be found in 31 different states in the U.S., including Hawaii (Isometrus maculatus).

Five colonies of scorpions (Euscorpius flavicaudis) have established themselves in southern England having probably arrived with imported fruit from Africa, but the number of colonies could be lower now because of the destruction of their habitats. This scorpion species is small and completely harmless to humans.

[edit] Suicide misconception

The belief that scorpions commit suicide by stinging themselves to death when surrounded by fire is of considerable antiquity and is often prevalent where these animals exist. It is nevertheless untrue since the venom has no effect on the scorpion itself, nor on any member of the same species (unless the venom is injected directly into the scorpion's nerve ganglion—quite an unlikely event outside of the laboratory). The misconception may derive from the fact that scorpions are poikilotherms (cold-blooded): when exposed to intense heat their metabolic processes malfunction. This causes the scorpion to spasm wildly and this spasming may appear as if the scorpion is stinging itself. It is also untrue that alcohol will cause scorpions to sting themselves to death.

[edit] Radiation

It is said that scorpions can survive high levels of radiation, such as that which results from the detonation of nuclear weapons. Indeed, scorpions have been observed surviving the radiation from nuclear weapons tests at French test sites in the Sahara.^[9] Scorpions are also known to glow when exposed to certain types of ultraviolet light such as that which is produced by a blacklight.

[edit] Classification

This classification is based on that of Soleglad & Fet (2003),^[10] which replaced the older, unpublished classification of Stockwell.^[11] Additional taxonomic changes are from Soleglad et al. (2005).^[12]

• ORDER SCORPIONES
  • Infraorder Orthosterni Pocock, 1911
    • Parvorder Pseudochactida Soleglad et Fet, 2003
      • Superfamily Pseudochactoidea Gromov, 1998
        • Family Pseudochactidae Gromov, 1998
    • Parvorder Buthida Soleglad et Fet, 2003
      • Superfamily Buthoidea C. L. Koch, 1837
        • Family Buthidae C. L. Koch, 1837 (thick-tailed scorpions)
        • Family Microcharmidae Lourenço, 1996
    • Parvorder Chaerilida Soleglad et Fet, 2003
      • Superfamily Chaeriloidea Pocock, 1893
        • Family Chaerilidae Pocock, 1893
    • Parvorder Iurida Soleglad et Fet, 2003
      • Superfamily Chactoidea Pocock, 1893
        • Family Chactidae Pocock, 1893
          • Subfamily Chactinae Pocock, 1893
            • Tribe Chactini Pocock, 1893
            • Tribe Nullibrotheini Soleglad et Fet, 2003
          • Subfamily Brotheinae Simon, 1879
            • Tribe Belisariini Lourenço, 1998
            • Tribe Brotheini Simon, 1879
              • Subtribe Brotheina Simon, 1879
              • Subtribe Neochactina Soleglad et Fet, 2003
          • Subfamily Uroctoninae
        • Family Euscorpiidae Laurie, 1896
          • Subfamily Euscorpiinae Laurie, 1896
          • Subfamily Megacorminae Kraepelin, 1905
            • Tribe Chactopsini Soleglad et Sissom, 2001
            • Tribe Megacormini Kraepelin, 1905
          • Subfamily Scorpiopinae Kraepelin, 1905
            • Tribe Scorpiopini Kraepelin, 1905
            • Tribe Troglocormini Soleglad et Sissom, 2001
        • Family Superstitioniidae Stahnke, 1940
          • Subfamily Superstitioniinae Stahnke, 1940
          • Subfamily Typlochactinae Mitchell, 1971
        • Family Vaejovidae Thorell, 1876
      • Superfamily Iuroidea Thorell, 1876
        • Family Iuridae Thorell, 1876
        • Family Caraboctonidae Kraepelin, 1905 (hairy scorpions)
          • Subfamily Caraboctoninae Kraepelin, 1905
          • Subfamily Hadrurinae Stahnke, 1974
      • Superfamily Scorpionoidea Latreille, 1802
        • Family Bothriuridae Simon, 1880
          • Subfamily Bothriurinae Simon, 1880
          • Subfamily Lisposominae Lawrence, 1928
        • Family Scorpionidae Latreille, 1802 (burrowing scorpions or pale-legged scorpions)
          • Subfamily Diplocentrinae Karsch, 1880
            • Tribe Diplocentrini Karsch, 1880
              • Tribe Nebini Kraepelin, 1905
          • Subfamily Scorpioninae Latreille, 1802
          • Subfamily Urodacinae Pocock, 1893
        • Family Hemiscorpiidae Pocock, 1893 (= Ischnuridae, =Liochelidae) (rock scorpions, creeping scorpions, or tree scorpions)
          • Subfamily Hemiscorpiinae Pocock, 1893
          • Subfamily Heteroscorpioninae Kraepelin, 1905
          • Subfamily Hormurinae Laurie, 1896

[edit] Cultural symbolism

The scorpion has had various meanings and representations in different cultures in history:

• In the Mesopotamian folklore, Gilgamesh, Gilgamesh approaches mountains where scorpion folk guard the entrance. Additionally, the Akkadians called the constellation Scorpius, Girtab, meaning the Seizer, or Stinger and "Place Where One Bows Down".

• In Egyptian mythology, the scorpion stands for Set, the Trickster and brother of Nephthys, nemesis and opponent of Osiris, and Isis.

• The Falaknuma Palace of Hyderabad, India, is laid out in the shape of a scorpion with the two pincers spreading out to the north as wings to the building.

• In Greek mythology, the scorpion is conjured by the gods to hound and punish Orion. It is also said that when Persius slew Medusa, the blood that leaked out of her severed neck turned into scorpions and snakes as it hit the ground.

[edit] Other use

From a Biblical quotation, it is the term for a severe Roman scourge. Hard material was fixed onto multiple thongs to give them a flesh-tearing bite [1 Kings 12:11: ...My father scourged you with whips; I will scourge you with scorpions]. The choice of the name testifies how much the hellish pain caused by the small animal is to be feared.

Its tail is also part of the Persian mythical monster manticore.

[edit] Pest control

Scorpions are difficult to control with pesticides alone. Therefore, the first control strategy is to modify the area surrounding a house.

• Remove all trash, logs, boards, stones, bricks and other objects from around the home.
• Keep grass closely mowed near the home. Prune bushes and overhanging tree branches away from the house. Tree branches can provide a path to the roof for scorpions.
• Store garbage containers in a frame that allows them to rest above ground level.
• Never bring firewood inside the house unless it is placed directly on the fire.
• Install weather-stripping around loose fitting doors and windows.
• Plug weep holes in brick veneer homes with steel wool, pieces of nylon scouring pad or small squares of screen wire.
• Caulk around roof eaves, pipes and any other cracks into the home.
• Keep window screens in good repair. Make sure they fit tightly in the window frame.

Wettable powder formulations provide better residual control for crawling pests when applying perimeter sprays. When using pyrethroids or other insecticides labeled for scorpion control, be sure to use the highest permissible label rate.

Apply pesticides around the foundation of the building and up to 1 foot above ground level on the exterior walls. Also apply pesticides around doors, window eaves and other potential points of entry. indiscriminate Cyfluthrin, bifenthrin, deltamethrin, and bendiocarb are effective pesticides.^[13]

[edit] In popular culture

• The Vz 61, a Czech-made submachine gun, is also known as the "Škorpion" from the Czech word for scorpion
• The United Nations Space Command's tank in the Halo series of video games is called the Scorpion.
• Sasori, a popular character in the manga/anime series Naruto, is named after a scorpion; 'sasori' being the Japanese word for a scorpion. His favorite puppet Hiruko in which he resides, resembles a scorpion with a curved tail and poisonous stinger. He is also a master of poisons, wielding poisonous weapons exclusively, and he is from the Hidden Village of the Sand located in a desert. (The bark scorpion resides in the deserts of Arizona.) His true form, also mainly a puppet, has a poisonous stinger which emerges from his stomach, and is similar to Scorpion's stinger from Mortal Kombat.
• The Transformers character Scorponok transformed into a giant scorpion. He appears in the 2007 film adaptation.
• In video games, one of the most famous Mortal Kombat characters is a ninja named Scorpion, whose signature move consists of skewering his opponent with a harpoon-like weapon, then reeling him in to hand-to-hand range, vaguely evocative of the combined use of a scorpion's tail and claws. In a fatality he turns into a giant scorpion.
• In comic books, one of Spider-Man's villains was a man called Mac Gargan. He was given the abilities of a scorpion through an experiment and was hired by J. Jonah Jameson to hunt down Spider-Man. Recently, Gargan came into contact with the Venom symbiote and became the new Venom.
• The Sasword Zecter in Kamen Rider Kabuto carries the motif of the scorpion.
• Professional Wrestler Sting uses scorpions for the background of his gimmick, and on his wrestling attire.
• The Professional Wrestling submission hold The Sharpshooter was originally called "The Scorpion Deathlock", mainly because when a wrestler performed the submission hold, he would arch the legs back in which mimicked the tail of a Scorpion. The wrestler who was trapped in the move would normally struggle to get to the ropes with his arms waved in front- again mimicking the pincers of a Scorpion.
• The Scorpion's tail is used as the symbol for the Brotherhood of Nod in the Command & Conquer video game series.
• Was the namesake of the 2002 film The Scorpion King featuring The Rock.
• The Pokémon Skorupi and Drapion are styled after scorpions. Also, Gligar and Gliscor are classified as flyscorpion Pokémon.
• Scorpion is class of battleship in the MMORPG EVE Online.
• In the MMORPG Guild Wars, there are monsters known as Devourers that are two tailed scorpions.
• In the videogame Sonic and the Secret Rings - the Sand Scorpion is the first Boss the player can face. However, its resemblance to an actual scorpion is questionable at best.
• In Final Fantasy VII, a mechanical scorpion is the first boss that Cloud and Barret fight in the Mako Reactor.
• In Final Fantasy XI, there exist large scorpion-type enemies known as Girtab. There is also a massive scorpion boss monster called Serket.
• Large, mutated scorpions called Radscorpions are a common enemy in the Fallout series of post-apocalyptic computer role-playing games. This is possibly a reference to the scorpion's resistance to radiation.
• A character who practices the "Scorpion Style" kung fu in the film Five Deadly Venoms.
• The German rock band Scorpions.
• The scorpion is a frequent enemy in the Dragon Quest RPG video games.
• In the El Mariachi,Desperado and Once Upon A Time In Mexico by Robert Rodriguez the main character El Mariachi wore a scorpion on his back.
• In the James Bond film Diamonds Are Forever (1971), assassins Wint and Kidd murder a smuggler/ dentist in South Africa by putting a scorpion down the neck of his shirt, whereas in Ian Fleming's original book, they merely observe and admire it ahead of their deadly assignment – before killing it with a rock.
• In the 2007 series of Doctor Who, in the episode The Lazarus Experiment, Professor Richard Lazarus (Mark Gatis) turns into a huge man/scorpion hybrid creature due to a change in his DNA.
• In an episode of Sealab 2021, when Captain Murphy winds up trapped, helpless and alone, for an extended period of time beneath a fallen vending machine, he develops an increasingly bizarre relationship with the scorpion who serves as his only living company.