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.
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 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]
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.
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 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 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.
Birth and development
Compsobuthus werneri female with young
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.
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.
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.
Geographical distribution
Hadrurus spadix - Caraboctonidae, Hadrurinae
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.
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.
Radiation
A scorpion under a
blacklight. In normal lighting this scorpion appears
black.
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.
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
- 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
Cultural symbolism
Bowl depicting scorpions. Excavated at Halilrud area. 3rd Millennium BC,
Jiroft
Kingdom,
Iran
The scorpion has had various meanings and representations in different cultures in history:
- In the Epic of 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 ancient Egypt, the scorpion was associated with the god Set.
- 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.
- 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.
- The tail of the Persian legendary monster manticore is a scorpion tail.
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. Cyfluthrin, bifenthrin, deltamethrin, and bendiocarb are effective
pesticides.[13]
In popular culture
- In Command and Conquer Nod used the Scorpion as their symbol.
- In the Halo video games, a large battle tank is called
the Scorpion after its shape.
- In John Steinbeck's The Pearl, the attack
of a scorpion on the protagonist's infant son sets the plot in motion.
- The Vz 61, a Czech-made submachine gun, is also known as the "Škorpion" from the Czech word for scorpion
- Sasori, a popular character in the manga/anime series Naruto, is named after the Japanese word for scorpion.
- The Transformers character Scorponok transformed into a giant scorpion. He appears in the 2007 film
adaptation.
- In the 1980s Filmation series She-Ra: Princess of Power, one of the
villains of The Evil Horde is a woman with scorpion features named Scorpia.
- In the 1980s film Clash of the Titans, giant scorpions spring up from the blood
of the severed head of Medusa, which ignite a battle with Perseus (played by Harry Hamlin).
- 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.
- 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.
- 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.
- In the 1986 international best-selling spy-thriller Scorpion (Novel), authored by
Andrew Kaplan, the main character's codename was Scorpion.
- 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.
- 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
Gattis) 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.
- In the Republic Pictures serial
Adventures of Captain Marvel, the Masked Mystery Villain calls himself the Scorpion, and is trying to reassemble an ancient
mystical weapon, the Golden Scorpion.
See also
References
- ^ http://www.sasionline.org/pepe.htm
- ^ Scorpion Sting
- ^ Sting Use In Two Species of Parabuthus Scorpions (Buthidae)
- ^ Hickman, Roberts, Larson, L'anson, Integrated Principles of Zoology, 13th
ed. McGraw Hill pp.380
- ^ Lourenco W. R., 2000, Reproduction in scorpions, with special reference to
parthenogenesis, European Arachnology, pp. 71-85
- ^ http://jeb.biologists.org/cgi/reprint/53/3/547.pdf http://www.scielo.br/pdf/jvatitd/v12n1/28301.pdf
- ^ http://www.amonline.net.au/factsheets/scorpions.htm
- ^ http://www.ucmp.berkeley.edu/arthropoda/chelicerata/eurypterida.html
- ^ Wee, Chua Kian (1997). What is a scorpion. Retrieved on
2007-05-03.
- ^ Soleglad, M. E. & V. Fet. 2003. High-level systematics and phylogeny of
the extant scorpions (Scorpiones: Orthosterni). Euscorpius, 11, pp. 1-175. (download from http://www.science.marshall.edu/fet/euscorpius/pubs.htm)
- ^ Scott A. Stockwell, 1989. Revision of the Phylogeny and Higher
Classification of Scorpions (Chelicerata). Ph.D. Dissertation, University of California, Berkeley
- ^ Soleglad, M.E.; Fet, V.; Kova{v{r. {{{title}}}. ík,
F. | year = 2005 | title = The Systematic Position of the Scorpion Genera Heteroscorpion Birula, 1903 and Urodacus Peters, 1861
(Scorpiones: Scorpionoidea) | publisher = Marshall University | isbn = }}
- ^ http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12510887&dopt=Abstract
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