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Scorpions are
predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroon ...
s of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always ending with a
stinger A stinger (or sting) is a sharp organ found in various animals (typically insects and other arthropods) capable of injecting venom, usually by piercing the epidermis of another animal. An insect sting is complicated by its introduction of ve ...
. The evolutionary history of scorpions goes back 435 million years. They mainly live in
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s but have adapted to a wide range of environmental conditions, and can be found on all continents except
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. There are over 2,500 described
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, with 22 extant (living) families recognized to date. Their
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
is being revised to account for 21st-century genomic studies. Scorpions primarily prey on
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s and other
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s, but some species hunt
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s. They use their pincers to restrain and kill prey, or to prevent their own predation. The venomous sting is used for offense and defense. During courtship, the male and female grasp each other's pincers and dance while he tries to move her onto his
sperm packet A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
. All known species give live birth and the female cares for the young as their
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
s harden, transporting them on her back. The exoskeleton contains
fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...
chemicals and glows under
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
light. The vast majority of species do not seriously threaten humans, and healthy adults usually do not need medical treatment after a sting. About 25 species (fewer than one percent) have venom capable of killing a human, which happens frequently in the parts of the world where they live, primarily where access to medical treatment is unlikely. Scorpions appear in art, folklore, mythology, and commercial brands.
Scorpion motif Many motifs are used in traditional kilims, handmade flat-woven rugs, each with many variations. In Turkish Anatolia in particular, village women wove themes significant for their lives into their rugs, whether before marriage or during marri ...
s are woven into
kilim A kilim ( az, Kilim کیلیم; tr, Kilim; tm, Kilim; fa, گلیم ''Gilīm'') is a flat tapestry- woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran, the Balkans and the Turkic countries. Ki ...
carpets for protection from their sting.
Scorpius Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation that pre-dates the Gr ...
is the name of a constellation; the corresponding astrological sign is Scorpio. A classical myth about Scorpius tells how the giant scorpion and its enemy Orion became constellations on opposite sides of the sky.


Etymology

The word "
scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always en ...
" originated in
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English p ...
between 1175 and 1225 AD from
Old French Old French (, , ; Modern French: ) was the language spoken in most of the northern half of France from approximately the 8th to the 14th centuries. Rather than a unified language, Old French was a linkage of Romance dialects, mutually intelligib ...
', or from Italian ', both derived from the Latin ', equivalent to ', which is the
romanization Romanization or romanisation, in linguistics, is the conversion of text from a different writing system to the Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing written text, and ...
of the Greek  – ', ultimately from
Proto-Indo-European root The roots of the reconstructed Proto-Indo-European language (PIE) are basic parts of words that carry a lexical meaning, so-called morphemes. PIE roots usually have verbal meaning like "to eat" or "to run". Roots never occurred alone in the lan ...
''*(s)ker-'' meaning "to cut", cf. "
shear Shear may refer to: Textile production *Animal shearing, the collection of wool from various species **Sheep shearing *The removal of nap during wool cloth production Science and technology Engineering *Shear strength (soil), the shear strength ...
".


Evolution


Fossil record

Scorpion
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s have been found in many strata, including marine
Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
and estuarine
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
deposits, coal deposits from the
Carboniferous Period The Carboniferous ( ) is a Period (geology), geologic period and System (stratigraphy), system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Myr, Mya), to the beginning of the Permian Period, ...
and in
amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In ...
. Whether the early scorpions were marine or terrestrial has been debated, though they had book lungs like modern terrestrial species. Over 100 fossil species of scorpion have been described. The oldest found as of 2021 is '' Dolichophonus loudonensis'', which lived during the Silurian, in present-day Scotland. '' Gondwanascorpio'' from the Devonian is among the earliest-known terrestrial animals on the
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
supercontinent. Some Palaeozoic scorpions possessed
compound eye A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which disti ...
s similar to those of eurypterids. The
Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...
fossils '' Protochactas'' and '' Protobuthus'' belong to the modern clades
Chactoidea The Chactidae are a family of scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic ...
and Buthoidea respectively, indicating that the crown group of modern scorpions had emerged by this time.


Phylogeny

The Scorpiones are a
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
within the pulmonate Arachnida (those with book lungs). Arachnida is placed within the
Chelicerata The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It contains the sea spiders, horseshoe crabs, and arachnids (including Opiliones, harvestmen, scorpions, spiders, Solifugae, solif ...
, a subphylum of
Arthropoda Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
that contains
sea spider Sea spiders are marine arthropods of the order Pantopoda ( ‘all feet’), belonging to the class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). They are cosmopolitan, fou ...
s and
horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to ar ...
s, alongside terrestrial animals without book lungs such as
tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s and
harvestmen The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of extan ...
. The extinct
Eurypterida Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is l ...
, sometimes called sea scorpions, though they were not all marine, are not scorpions; their grasping pincers were
chelicerae The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or similarly ...
, not homologous with the pincers (second appendages) of scorpions. Scorpiones is
sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a family, familial relationship, it is sometimes used endearingly to r ...
to the
Tetrapulmonata Tetrapulmonata is a non-ranked supra-ordinal clade of arachnids. It is composed of the extant orders Thelyphonida (whip scorpions), Schizomida (short-tailed whip scorpions), Amblypygi (tail-less whip scorpions) and Araneae (spiders). It is th ...
, a terrestrial group of pulmonates containing the
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s and whip scorpions. This 2019
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
summarizes: Recent studies place
pseudoscorpion Pseudoscorpions, also known as false scorpions or book scorpions, are small, scorpion-like arachnids belonging to the order Pseudoscorpiones, also known as Pseudoscorpionida or Chelonethida. Pseudoscorpions are generally beneficial to humans sin ...
s as the sister group of scorpions in the clade Panscorpiones, which together with Tetrapulmonata makes up the clade Arachnopulmonata. The internal
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spe ...
of the scorpions has been debated, but genomic analysis consistently places the Bothriuridae as sister to a clade consisting of Scorpionoidea and
Chactoidea The Chactidae are a family of scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic ...
. The scorpions diversified between the Devonian and the early
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
. The main division is into the clades Buthida and Iurida. The Bothriuridae diverged starting before temperate Gondwana broke up into separate land masses, completed by the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
. The Iuroidea and Chactoidea are both seen not to be single clades, and are shown as "
paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
" (with quotation marks) in this 2018 cladogram.


Taxonomy

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
described six species of scorpion in his genus ''Scorpio'' in 1758 and 1767; three of these are now considered valid and are called '' Scorpio maurus'', '' Androctonus australis'', and ''
Euscorpius ''Euscorpius'' is a genus of scorpions, commonly called small wood-scorpions. It presently contains 65 species and is the type genus of the family Euscorpiidae – long included in the ChactidaeRein (2008a) – and the subfamily Euscorpiinae. ...
carpathicus''; the other three are dubious names. He placed the scorpions among his "Insecta aptera" (wingless insects), a group that included Crustacea, Arachnida and
Myriapoda Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. The fossil record of myriapods reaches back into the late Silurian ...
. In 1801,
Jean-Baptiste Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biologi ...
divided up the "Insecta aptera", creating the
taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
Arachnides for spiders, scorpions, and acari (mites and ticks), though it also contained the
Thysanura Thysanura is the now deprecated name of what was, for over a century, recognised as an order in the class Insecta. The two constituent groups within the former order, the Archaeognatha (jumping bristletails) and the Zygentoma (silverfish and fireb ...
(thrips), Myriapoda and parasites such as lice. German
arachnologist Arachnology is the scientific study of arachnids, which comprise spiders and related invertebrates such as scorpions, pseudoscorpions, and harvestmen. Those who study spiders and other arachnids are arachnologists. More narrowly, the study of ...
Carl Ludwig Koch Carl Ludwig Koch (21 September 1778 – 23 August 1857) was a German entomologist and arachnologist. He was responsible for classifying a great number of spiders, including the Brazilian whiteknee tarantula and common house spider. He was bo ...
created the order Scorpiones in 1837. He divided it into four families, the six-eyed scorpions "Scorpionides", the eight-eyed scorpions "Buthides", the ten-eyed scorpions "Centrurides", and the twelve-eyed scorpions "Androctonides". More recently, some twenty-two families containing over 2,500 species of scorpions have been described, with many additions and much reorganization of taxa in the 21st century. There are over 100 described taxa of fossil scorpions. This classification is based on Soleglad and Fet (2003), which replaced Stockwell's older, unpublished classification. Further taxonomic changes are from papers by Soleglad et al. (2005). The extant taxa to the
rank Rank is the relative position, value, worth, complexity, power, importance, authority, level, etc. of a person or object within a ranking, such as: Level or position in a hierarchical organization * Academic rank * Diplomatic rank * Hierarchy * ...
of
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
(numbers of species in parentheses) are: ; Order Scorpiones * Parvorder Pseudochactida Soleglad &
Fet The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contr ...
, 2003
** Superfamily Pseudochactoidea
Gromov Gromov (russian: Громов) is a Russian male surname, its feminine counterpart is Gromova (Громова). Gromov may refer to: * Alexander Georgiyevich Gromov (born 1947), Russian politician and KGB officer * Alexander Gromov (born 1959), R ...
, 1998
*** Family Pseudochactidae
Gromov Gromov (russian: Громов) is a Russian male surname, its feminine counterpart is Gromova (Громова). Gromov may refer to: * Alexander Georgiyevich Gromov (born 1947), Russian politician and KGB officer * Alexander Gromov (born 1959), R ...
, 1998
(1 sp.) (Central Asian scorpions of semi-
savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
habitats) * Parvorder Buthida Soleglad &
Fet The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contr ...
, 2003
** Superfamily Buthoidea C. L. Koch, 1837 *** Family
Buthidae The Buthidae are the largest family of scorpions, containing about 100 genera and 1339 species as of 2022. A few very large genera (''Ananteris'', '' Centruroides'', '' Compsobuthus'', or '' Tityus'') are known, but a high number of species-poor ...
C. L. Koch, 1837 (1209 spp.) (thick-tailed scorpions, including the most dangerous species) *** Family Microcharmidae
Lourenço Lourenço is a town and district in the Brazilian municipality of Calçoene, in the interior of the state of Amapá. The main economic activities of the town is gold mining. It is one of the oldest mines in Brazil. History Gold mining in Louren ...
, 1996, 2019
(17 spp.) (African scorpions of humid forest leaf litter) * Parvorder Chaerilida Soleglad &
Fet The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contr ...
, 2003
** Superfamily Chaeriloidea Pocock, 1893 *** Family
Chaerilidae Chaerilidae is a family of scorpions. It contains two genera, the extant ''Chaerilus'' (Simon, 1877) and the extinct ''Electrochaerilus'' (Santiago-Blay, Fet, Soleglad & Anderson, 2004). References External links

* Scorpion familie ...
Pocock, 1893 (51 spp.) (South and Southeast Asian scorpions of non-arid places) * Parvorder Iurida Soleglad &
Fet The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contr ...
, 2003
** Superfamily
Chactoidea The Chactidae are a family of scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic ...
Pocock, 1893 *** Family Akravidae Levy, 2007 (1 sp.) (cave-dwelling scorpions of Israel) *** Family Belisariidae
Lourenço Lourenço is a town and district in the Brazilian municipality of Calçoene, in the interior of the state of Amapá. The main economic activities of the town is gold mining. It is one of the oldest mines in Brazil. History Gold mining in Louren ...
, 1998
(3 spp.) (cave-related scorpions of Southern Europe) *** Family Chactidae Pocock, 1893 (209 spp.) (New World scorpions, membership under revision) *** Family Euscorpiidae Laurie, 1896 (170 spp.) (harmless scorpions of the Americas, Eurasia, and North Africa) *** Family Superstitioniidae Stahnke, 1940 (1 sp.) (cave scorpions of Mexico and Southwestern United States) *** Family
Troglotayosicidae Troglotayosicidae is a family of scorpions Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characterist ...
Lourenço Lourenço is a town and district in the Brazilian municipality of Calçoene, in the interior of the state of Amapá. The main economic activities of the town is gold mining. It is one of the oldest mines in Brazil. History Gold mining in Louren ...
, 1998
(4 spp.) (cave-related scorpions of South America) *** Family Typhlochactidae Mitchell, 1971 (11 spp.) (cave-related scorpions of Eastern Mexico) *** Family
Vaejovidae Vaejovidae is a family of scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic for ...
Thorell, 1876 (222 spp.) (New World scorpions) ** Superfamily
Iuroidea The Iuridae are a family of scorpions in the order Scorpiones. Six genera and at least 20 described species are placed in the Iuridae. Genera * '' Anuroctonus'' * '' Calchas'' * ''Hadrurus ''Hadrurus'' is a genus of scorpions which belongs ...
Thorell, 1876 *** Family
Caraboctonidae The Caraboctonidae (hairy scorpions) are part of the superfamily Iuroidea. The family was established by Karl Kraepelin in 1905. List of genera and species * '' Hadrurus'' ** '' H. arizonensis'' ** '' H. spadix'' References {{Taxonbar, ...
Kraepelin, 1905 (23 spp.) (hairy scorpions) *** Family Hadruridae Stahnke, 1974 (9 spp.) (large North American scorpions) *** Family Iuridae Thorell, 1876 (21 spp.) (scorpions with a large tooth on inner side of moveable claw) ** Superfamily
Scorpionoidea The Scorpionidae (burrowing scorpions or pale-legged scorpions) make up the superfamily Scorpionoidea. The family was established by Pierre André Latreille, 1802. Genera Scorpionidae contains the following genera: * '' Aops'' Volschenk & Pr ...
Latreille, 1802 *** Family Bothriuridae
Simon Simon may refer to: People * Simon (given name), including a list of people and fictional characters with the given name Simon * Simon (surname), including a list of people with the surname Simon * Eugène Simon, French naturalist and the genus ...
, 1880
(158 spp.) (Southern hemisphere tropical and temperate scorpions) *** Family Hemiscorpiidae Pocock, 1893 (16 spp.) (rock, creeping, or tree scorpions of the Middle East) *** Family
Hormuridae Hormuridae is a family of scorpions in the order Scorpiones. There are about 10 genera and more than 90 described species in Hormuridae. Genera These 11 genera belong to the family Hormuridae: * ''Cheloctonus'' Pocock, 1892 * ''Chiromachetes'' ...
Laurie, 1896 (92 spp.) (flattened, crevice-living scorpions of Southeast Asia and Australia) *** Family Rugodentidae Bastawade et al., 2005 (1 sp.) (burrowing scorpions of India) *** Family
Scorpionidae The Scorpionidae (burrowing scorpions or pale-legged scorpions) make up the superfamily Scorpionoidea. The family was established by Pierre André Latreille Pierre André Latreille (; 29 November 1762 – 6 February 1833) was a French zool ...
Latreille, 1802 (183 spp.) (burrowing or pale-legged scorpions) *** Family Diplocentridae Karsch, 1880 (134 spp.) (closely related to and sometimes placed in Scorpionidae, but have spine on telson) *** Family Heteroscorpionidae Kraepelin, 1905 (6 spp.) (scorpions of Madagascar)


Geographical distribution

Scorpions are found on all continents except
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. The diversity of scorpions is greatest in subtropical areas; it decreases toward the poles and equator, though scorpions are found in the tropics. Scorpions did not occur naturally in
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...
but were accidentally introduced by humans, and have now established a population.
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
, and some of the islands in
Oceania Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
, have in the past had small populations of introduced scorpions, but they were exterminated. Five colonies of '' Euscorpius flavicaudis'' have established themselves since the late 19th century in Sheerness in England at 51°N, while '' Paruroctonus boreus'' lives as far north as
Red Deer, Alberta Red Deer is a city in Alberta, Canada, located midway on the Calgary–Edmonton Corridor. Red Deer serves central Alberta, and key industries include health care, retail trade, construction, oil and gas, hospitality, manufacturing and education. ...
, at 52°N. A few species are on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
; '' Lychas braueri'' is classed as critically endangered (2014), '' Isometrus deharvengi'' as
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
(2016) and '' Chiromachus ochropus'' as vulnerable (2014). Scorpions are
xerocole A xerocole (), is a general term referring to any animal that is adapted to live in a desert. The main challenges xerocoles must overcome are lack of water and excessive heat. To conserve water they avoid evaporation and concentrate excretions (i ...
s, meaning they primarily live in
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s, but they can be found in virtually every terrestrial
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
including high-elevation mountains, caves, and intertidal zones. They are largely absent from
boreal ecosystem A boreal ecosystem is an ecosystem with a subarctic climate located in the Northern Hemisphere, approximately between 50° to 70°N latitude. These ecosystems are commonly known as taiga and are located in parts of North America, Europe, and Asia. ...
s such as the
tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless mou ...
, high-altitude
taiga Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruce ...
, and mountain tops. The highest altitude reached by a scorpion is in the Andes, for '' Orobothriurus crassimanus''. As regards
microhabitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s, scorpions may be ground-dwelling, tree-loving, rock-loving or sand-loving. Some species, such as '' Vaejovis janssi'', are versatile and are found in all habitats on
Socorro Island Socorro Island ( es, Isla Socorro) is a small volcanic island in the Revillagigedo Islands, a Mexican possession lying off the country's western coast. The size is 16.5 by 11.5 km (10.25 by 7.15 miles), with an area of . It is the largest ...
,
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, while others such as ''
Euscorpius carpathicus ''Euscorpius carpathicus'' is a species of scorpion endemic to the Romanian Carpathians. It is the type species of the genus ''Euscorpius''. Taxonomy Numerous species were previously identified as part of the ''Escorpius carpathicus'' species ...
'',
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to the
littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal a ...
of rivers in Romania, occupy specialized niches.


Morphology

Scorpions range in size from the '' Typhlochactas mitchelli'' of Typhlochactidae, to the ''
Heterometrus swammerdami ''Gigantometrus swammerdami'', commonly called the giant forest scorpion, is a scorpion belonging to the family Scorpionidae. It is native to India. It is the world's largest scorpion species with 23 cm (9 in) in length, and weigh as m ...
'' of Scorpionidae. The body of a scorpion is divided into two parts or tagmata: the
cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
or
prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
, and the abdomen or
opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma (cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects to a ...
. The opisthosoma is subdivided into a broad anterior portion, the
mesosoma The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings. In hymenopterans of ...
or pre-abdomen, and a narrow tail-like posterior, the
metasoma The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circul ...
or post-abdomen. External differences between the sexes are not obvious in most species. In some, the metasoma is more elongated in males than females.


Cephalothorax

The cephalothorax comprises the
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
, eyes, chelicerae (mouth parts),
pedipalp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") an ...
s (which have
chelae A chela ()also called a claw, nipper, or pinceris a pincer (biology), pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are ...
, commonly called claws or pincers) and four pairs of walking legs. 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. While unable to form sharp images, their central eyes are amongst the most light sensitive in the animal kingdom, especially in dim light, and makes it possible for nocturnal species to use starlight to navigate at night. The chelicerae are at the front and underneath the carapace. They are pincer-like and have three segments and sharp "teeth". The brain of a scorpion is in the back of the cephalothorax, just above the
esophagus The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...
. As in other arachnids, the nervous system is highly concentrated in the cephalothorax, but has a long ventral nerve cord with segmented ganglia which may be a primitive trait. The pedipalp is a segmented, clawed appendage used for prey immobilization, defense and sensory purposes. The segments of the pedipalp (from closest to the body outward) are coxa, trochanter, femur, patella, tibia (including the fixed claw and the manus) and tarsus (moveable claw). A scorpion has darkened or granular raised linear ridges, called "keels" or "carinae" on the pedipalp segments and on other parts of the body; these are useful as taxonomic
characters Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...
. Unlike those of some other arachnids, the legs have not been modified for other purposes, though they may occasionally be used for digging, and females may use them to catch emerging young. The legs are covered in
proprioceptor Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...
s,
bristle A bristle is a stiff hair or feather (natural or artificial), either on an animal, such as a pig, a plant, or on a tool such as a brush or broom. Synthetic types Synthetic materials such as nylon are also used to make bristles in items such as ...
s and sensory
setae In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. ...
. Depending on the species, the legs may have spines and spurs.


Mesosoma

The mesosoma or preabdomen is the broad part of the opisthosoma. In the early stages of embryonic development the mesosoma consist of eight segments, but the first segment disappear before birth, so the mesosoma in scorpions actually consist of segments 2-8. These anterior seven
somite The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide ...
s (segments) of the opisthosoma are each covered
dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
by a sclerotized plate called the
tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...
.
Ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
ly, somites 3 to 7 are armored with matching plates called
sternites The sternum (pl. "sterna") is the ventral portion of a segment of an arthropod thorax or abdomen. In insects, the sterna are usually single, large sclerites, and external. However, they can sometimes be divided in two or more, in which case the ...
. The ventral side of somite 1 has a pair of genital opercula covering the
gonopore A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female it is t ...
. Sternite 2 forms the basal plate bearing the pectines, which function as sensory organs. The next four somites, 3 to 6, all bear pairs of spiracles. They serve as openings for the scorpion's respiratory organs, known as
book lungs A book lung is a type of respiration organ used for atmospheric gas exchange that is present in many arachnids, such as scorpions and spiders. Each of these organs is located inside an open ventral abdominal, air-filled cavity (atrium) and con ...
. The spiracle openings may be slits, circular, elliptical or oval according to the species. There are thus four pairs of book lungs; each consists of some 140 to 150 thin
lamellae Lamella (plural lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal * ...
filled with air inside a pulmonary chamber, connected on the ventral side to an atrial chamber which opens into a spiracle. Bristles hold the lamellae apart. A muscle opens the spiracle and widens the atrial chamber; dorsoventral muscles contract to compress the pulmonary chamber, forcing air out, and relax to allow the chamber to refill. The 7th and last somite does not bear appendages or any other significant external structures. The mesosoma contains the heart or "dorsal vessel" which is the center of the scorpion's
open circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
. The heart is continuous with a deep arterial system which spreads throughout the body. Sinuses return deoxygenated blood (
hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
) to the heart; the blood is re-oxygenated by cardiac pores. The mesosoma also contains the reproductive system. The female
gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...
s are made of three or four tubes that run parallel to each other and are connected by two to four transverse
anastomoses An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be norm ...
. These tubes are the sites for both
oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...
formation and embryonic development. They connect to two
oviduct The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, o ...
s which connect to a single atrium leading to the genital orifice. Males have two gonads made of two cylindrical tubes with a ladder-like configuration; they contain cysts which produce
spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromos ...
. Both tubes end in a spermiduct, one on each side of the mesosoma. They connect to glandular symmetrical structures called paraxial organs, which end at the genital orifice. These secrete chitin-based structures which come together to form the
spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
.


Metasoma

The "tail" or metasoma consists of five segments and the
telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ...
, which is not strictly a segment. The five segments are merely body rings; they lack apparent sterna or terga, and become larger distally. These segments have keels, setae and bristles which may be used for taxonomic classification. The anus is at the distal and ventral end of the last segment, and is encircled by four anal papillae and the anal arch. The tails of some species contain light receptors. The telson includes the
vesicle Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry) In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form nat ...
, which contains a symmetrical pair of
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...
glands. Externally it bears the curved stinger, the hypodermic aculeus, equipped with sensory hairs. Each of the venom glands has its own duct to convey its secretion along the aculeus from the bulb of the gland to immediately near of the tip, where each of the paired ducts has its own venom pore. An extrinsic muscle system in the tail moves it forward and propels and penetrates with the aculeus, while an intrinsic muscle system attached to the glands pumps venom through the stinger into the intended victim. The stinger contains
metalloprotein Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains al ...
s with zinc, hardening the tip. The optimal stinging angle is around 30 degrees relative to the tip.


Biology

Most scorpion species are nocturnal or crepuscular, finding shelter during the day in burrows, cracks in rocks and tree bark. Many species dig a shelter underneath stones a few centimeters long. Some may use burrows made by other animals including spiders, reptiles and small mammals. Other species dig their own burrows which vary in complexity and depth. ''
Hadrurus ''Hadrurus'' is a genus of scorpions which belongs to the family Caraboctonidae. They are found in sandy deserts and other xeric habitats in northwestern Mexico and in southwest United States. They are among the largest of all scorpion genera, o ...
'' species dig burrows as over deep. Digging is done using the mouth parts, claws and legs. In several species, particularly of the family Buthidae, individuals may gather in the same shelter; bark scorpions may aggregate up to 30 individuals. In some species, families of females and young sometimes aggregate. Scorpions prefer areas where the temperature remains in the range of , but may survive temperatures from well below freezing to desert heat. Scorpions can withstand intense heat: '' Leiurus quinquestriatus'', ''Scorpio maurus'' and ''
Hadrurus arizonensis ''Hadrurus arizonensis'', the giant desert hairy scorpion, giant hairy scorpion, or Arizona Desert hairy scorpion is a large scorpion found in North America. Description ''H. arizonensis'' is the largest scorpion in North America, and one of th ...
'' can live in temperatures of if they are sufficiently hydrated. Desert species must deal with the extreme changes in temperature from day to night or between seasons; '' Pectinibuthus birulai'' lives in a temperature range of . Scorpions that live outside deserts prefer lower temperatures. The ability to resist cold may be related to the increase in the sugar
trehalose Trehalose (from Turkish '' tıgala'' – a sugar derived from insect cocoons + -ose) is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it ...
when the temperature drops. Some species
hibernate Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
. Scorpions appear to have resistance to ionizing radiation. This was discovered in the early 1960s when scorpions were found to be among the few animals to survive nuclear tests at
Reggane Reggane (from Berber "Argan"; ar, رقان) is a town and commune, and the capital of Reggane District, in Adrar Province, central Algeria. Reggane lies in the Sahara Desert near an oasis. According to the 2008 census it has a population of 20,4 ...
, Algeria. Desert scorpions have several adaptations for water conservation. They excrete insoluble compounds such as
xanthine Xanthine ( or ; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine base found in most human body tissues and fluids, as well as in other organisms. Several stimulants are derived from xanthine, including caffeine ...
,
guanine Guanine () ( symbol G or Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is c ...
, and
uric acid Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown ...
, not requiring water for their removal from the body. Guanine is the main component and maximizes the amount of nitrogen excreted. A scorpion's cuticle holds in moisture via
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
s and waxes from epidermal glands, and protects against
ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
. Even when dehydrated, a scorpion can tolerate high osmotic pressure in its blood. Desert scorpions get most of their moisture from the food they eat but some can absorb water from the humid soil. Species that live in denser vegetation and in more moderate temperatures will drink water on plants and in puddles. A scorpion uses its stinger both for killing prey and defense. Some species make direct, quick strikes with their tails while others make slower, more circular strikes which can more easily return the stinger to a position where it can strike again. ''Leiurus quinquestriatus'' can whip its tail at a speed of up to in a defensive strike.


Mortality and defense

Scorpions may be attacked by other arthropods like ants, spiders,
solifugids Solifugae is an order of animals in the class Arachnida known variously as camel spiders, wind scorpions, sun spiders, or solifuges. The order includes more than 1,000 described species in about 147 genera. Despite the common names, they are nei ...
and
centipede Centipedes (from New Latin , "hundred", and Latin , " foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', lip, and New Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, an ...
s. Major
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s include frogs, lizards, snakes, birds, and mammals. Meerkats are somewhat specialized in preying on scorpions, biting off their stingers and being immune to their venom. Other predators adapted for hunting scorpions include the
grasshopper mouse Grasshopper mice are rodents of the genus ''Onychomys'', occurring in North America. They feed on insects and other arthropods. Biology The three species in this genus of New World mice are only distantly related to the common house mouse, '' ...
and desert long-eared bat, which are also immune to their venom. In one study, 70% of the latter's droppings contained scorpion fragments. Scorpions host parasites including
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...
s, scuttle flies,
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
s and some bacteria. The
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
of scorpions gives them resistance to infection by many types of bacteria. When threatened, a scorpion raises its claws and tail in a defensive posture. Some species
stridulate Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
to warn off predators by rubbing certain hairs, the stinger or the claws. Certain species have a preference for using either the claws or stinger as defense, depending on the size of the appendages. A few scorpions, such as ''
Parabuthus ''Parabuthus'', commonly known as the thick-tailed scorpion, is a genus of large and highly venomous Afrotropical scorpions, that show a preference for areas of low rainfall. Their stings are medically important and human fatalities have been re ...
'', ''
Centruroides margaritatus ''Centruroides'' is a genus of scorpions of the family Buthidae. Several North American species are known by the common vernacular name bark scorpion. Numerous species are extensively found throughout the southern United States, Mexico, Centr ...
'', and ''Hadrurus arizonensis'', squirt venom in a narrow jet as far as to warn off potential predators, possibly injuring them in the eyes. Some ''
Ananteris ''Ananteris'' is a little-known genus of rare scorpions. It contains 84 species found in South America. Species include: *'' Ananteris balzanii'' Thorell, 1891 *'' Ananteris dacostai'' Ythier, Chevalier & Lourenço, 2020 *'' Ananteris pydanieli'' ...
'' species can shed parts of their tail to escape predators. The parts do not grow back, leaving them unable to sting and defecate, but they can still catch small prey and reproduce for at least eight months afterward.


Diet and feeding

Scorpions generally prey on insects, particularly grasshoppers,
cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...
s,
termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blatto ...
s,
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s and
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
s. Other prey include spiders, solifugids,
woodlice A woodlouse (plural woodlice) is an isopod crustacean from the polyphyleticThe current consensus is that Oniscidea is actually triphyletic suborder Oniscidea within the order Isopoda. They get their name from often being found in old wood. ...
and even small
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s including lizards, snakes and mammals. Species with large claws may prey on earthworms and mollusks. The majority of species are opportunistic and consume a variety of prey though some may be highly specialized; '' Isometroides vescus'' specializes on burrowing spiders. Prey size depends on the size of the species. Several scorpion species are
sit-and-wait predator Ambush predators or sit-and-wait predators are carnivorous animals that capture or trap prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey ...
s, which involves them waiting for prey at or near the entrance to their burrow. Others actively seek them out. Scorpions detect their prey with mechanoreceptive and chemoreceptive hairs on their bodies and capture them with their claws. Small animals are merely killed with the claws, particularly by large-clawed species. Larger and more aggressive prey is given a sting. Scorpions, like other arachnids, digest their food externally. The chelicerae, which are very sharp, are used to pull small amounts of food off the prey item into a pre-oral cavity below the chelicerae and carapace. The digestive juices from the gut are egested onto the food, and the digested food is then sucked into the gut in liquid form. Any solid indigestible matter (such as
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
fragments) is trapped by
seta In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. ...
e in the pre-oral cavity and ejected. The sucked-in food is pumped into the midgut by the pharynx, where it is further digested. The waste passes through the hindgut and out of the anus. Scorpions can consume large amounts of food during one meal. They have an efficient food storage organ and a very low metabolic rate, and a relatively inactive lifestyle. This enables some to survive six to twelve months of starvation.


Mating

Most scorpions reproduce sexually, with male and female individuals; species in some genera, such as ''Hottentotta'' and ''Tityus (genus), Tityus'', and the species ''Centruroides gracilis'', ''Liocheles australasiae'', and ''Ananteris coineaui'' have been reported, not necessarily reliably, to reproduce through parthenogenesis, in which unfertilized eggs develop into living embryos. Receptive females produce pheromones which are picked up by wandering males using their pectines to comb the substrate. Males begin courtship by moving their bodies back and forth, without moving the legs, a behavior known as juddering. This appears to produce ground vibrations that are picked up by the female. The pair then make contact using their pedipalps, and perform a dance called the ''promenade à deux'' (French for "a walk for two"). In this dance, the male and female move back and forth while facing each other, as the male searches for a suitable place to deposit his spermatophore. The courtship ritual can involve several other behaviors such as a cheliceral kiss, in which the male and female grasp each other's mouth-parts, ''arbre droit'' ("upright tree") where the partners elevate their posteriors and rub their tails together, and sexual stinging, in which the male stings the female in the chelae or mesosoma to subdue her. The dance can last from a few minutes to several hours. When the male has located a suitably stable substrate, such as hard ground, agglomerated sand, rock, or tree bark, he deposits the spermatophore and guides the female over it. This allows the spermatophore to enter her genital opercula, which triggers release of the sperm, thus fertilizing the female. A mating plug then forms in the female to prevent her from mating again before the young are born. The male and female then abruptly separate. Sexual cannibalism after mating has only been reported anecdotally in scorpions.


Birth and development

Gestation in scorpions can last for over a year in some species. They have two types of embryonic development; apoikogenic and katoikogenic. In the apoikogenic system, which is mainly found in the Buthidae, embryos develop in yolk-rich eggs inside Ovarian follicle, follicles. The katoikogenic system is documented in Hemiscorpiidae, Scorpionidae and Diplocentridae, and involves the embryos developing in a diverticulum which has a teat-like structure for them to feed though. Unlike the majority of arachnids, which are oviparous, hatching from eggs, scorpions seem to be universally viviparous, with live births. They are unusual among terrestrial arthropods in the amount of care a female gives to her offspring. The size of a brood varies by species, from 3 to over 100. The body size of scorpions is not correlated either with brood size or with life cycle length. Before giving birth, the female elevates the front of her body and positions her pedipalps and front legs under her to catch the young ("birth basket"). The young emerge one by one from the genital opercula, expel the embryonic membrane, if any, and are placed on the mother's back where they remain until they have gone through at least one ecdysis, molt. The period before the first molt is called the pro-juvenile stage; the young are unable to feed or sting, but have Sucker (zoology), suckers on their tarsi, used to hold on to their mother. This period lasts 5 to 25 days, depending on the species. The brood molt for the first time simultaneously in a process that lasts 6 to 8 hours, marking the beginning of the juvenile stage. Juvenile stages or instars generally resemble smaller versions of adults, with fully developed pincers, hairs and stingers. They are still soft and lack pigments, and thus continue to ride on their mother's back for protection. They become harder and more pigmented over the next couple of days. They may leave their mother temporarily, returning when they sense potential danger. Once the exoskeleton is fully hardened, the young can hunt prey on their own and may soon leave their mother. A scorpion may molt six times on average before reaching maturity, which may not occur until it is 6 to 83 months old, depending on the species. Some species may live up to 25 years.


Fluorescence

Scorpions glow a vibrant blue-green when exposed to certain wavelengths ranges of
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
light such as that produced by a black light, due to
fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...
chemicals such as beta-carboline in the cuticle. Accordingly, a hand-held ultraviolet lamp has long been a standard tool for nocturnal field surveys of these animals. Fluorescence occurs as a result of sclerotization and increases in intensity with each successive instar. This fluorescence may have an active role in the scorpion's ability to detect light.


Relationship with humans


Stings

Scorpion venom serves to kill or paralyze prey rapidly. The Scorpion sting, stings of many species are uncomfortable, but only 25 species have venom that is deadly to humans. Those species belong to the family Buthidae, including ''Leiurus quinquestriatus'', ''Hottentotta'' spp., ''Centruroides'' spp., and ''Androctonus'' spp. People with Allergy, allergies are especially at risk; otherwise, first aid is Symptomatic treatment, symptomatic, with Analgesic, analgesia. Hypertensive emergency, Cases of very high blood pressure are treated with medications that anxiolytic, relieve anxiety and Vasodilation, relax the blood vessels. Scorpion envenomation with high morbidity and mortality is usually due to either excessive Autonomic nervous system, autonomic activity and cardiovascular toxic effects, or neuromuscular toxic effects. Antivenom is the specific treatment for scorpion envenomation combined with supportive measures including vasodilators in patients with cardiovascular toxic effects, and benzodiazepines when there is neuromuscular involvement. Although rare, severe hypersensitivity reactions including anaphylaxis to scorpion antivenin are possible. Scorpion stings are a public health problem, particularly in the tropical and subtropical regions of the Americas, North Africa, the Middle East and India. Around 1.5 million scorpion envenomations occur each year with around 2,600 deaths. Mexico is one of the most affected countries, with the highest biodiversity of scorpions in the world, some 200,000 envenomations per year and at least 300 deaths. Efforts are made to prevent envenomation and to control scorpion populations. Prevention encompasses personal activities such as checking shoes and clothes before putting them on, not walking in bare feet or sandals, and filling in holes and cracks where scorpions might nest. Street lighting reduces scorpion activity. Control may involve the use of insecticides such as pyrethroids, or gathering scorpions manually with the help of ultraviolet lights. Domestic predators of scorpions, such as chickens and turkeys, can help to reduce the risk to a household.


Potential medicinal use

Scorpion venom is a mixture of neurotoxins; most of these are peptides, chains of amino acids. Many of them interfere with membrane channels that Sodium channel, transport sodium, Potassium channel, potassium, calcium channel, calcium, or Chloride channel, chloride ions. These channels are essential for nerve conduction, muscle contraction and many other biological processes. Some of these molecules may be useful in medical research and might lead to the development of new disease treatments. Among their potential therapeutic uses are as analgesic, anti-cancer, antibacterial, antifungal, antiviral, antiparasitic, bradykinin-potentiating, and immunosuppressive drugs. As of 2020, no scorpion toxin-based drug is on sale, though chlorotoxin is being trialled for use against glioma, a brain cancer.


Consumption

Scorpions are eaten by people in West Africa, Myanmar and East Asia. Fried scorpion is traditionally eaten in Shandong cuisine, Shandong, China. There, scorpions can be cooked and eaten in a variety of ways, including roasting, frying, grilling, raw, or alive. The stingers are typically not removed, since direct and sustained heat negates the harmful effects of the venom. In Thailand, scorpions are not eaten as often as other arthropods, such as grasshoppers, but they are sometimes fried as street food. They are used in Vietnam to make snake wine (scorpion wine).


Pets

Scorpions are often kept as pets. They are relatively simple to keep, the main requirements being a secure enclosure such as a glass terrarium with a lockable lid and the appropriate temperature and humidity for the chosen species, which typically means installing a heating mat and spraying regularly with a little water. The substrate needs to resemble that of the species' natural environment, such as peat for forest species, or lateritic sand for burrowing desert species. Scorpions in the genera ''Pandinus'' and ''Heterometrus'' are docile enough to handle. A large ''Pandinus'' may consume up to three crickets each week. Cannibalism is more common in captivity than in the wild and can be minimized by providing many small shelters within the enclosure and ensuring there is plenty of prey. The pet trade has threatened wild populations of some scorpion species, particularly ''Androctonus australis'' and ''Pandinus imperator''.


Culture

File:Egyptian - Figure of Isis-Serget as Scorpion - Walters 54546 - Side A (cropped).jpg, Late period bronze figure of Isis-Serket Scorpion and snake fighting Anglo-Saxon c 1050.jpg, "Scorpion and snake fighting", Cotton Vitellius, ''Anglo-Saxon Herbal'', c. 1050 File:Sidney Hall - Urania's Mirror - Scorpio.jpg, The constellation Scorpius, depicted in ''Urania's Mirror'' as "Scorpio", London, c. 1825 File:Scorpion kilim motif.jpg, A Kilim motifs, scorpion motif (two types shown) was often woven into Turkish ''
kilim A kilim ( az, Kilim کیلیم; tr, Kilim; tm, Kilim; fa, گلیم ''Gilīm'') is a flat tapestry- woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran, the Balkans and the Turkic countries. Ki ...
'' flatweave carpets, for protection from their sting.
The scorpion is a culturally significant animal, appearing as a Motif (visual arts), motif in art, especially in Islamic art in the Middle East. A Kilim motifs, scorpion motif is often woven into Turkish
kilim A kilim ( az, Kilim کیلیم; tr, Kilim; tm, Kilim; fa, گلیم ''Gilīm'') is a flat tapestry- woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran, the Balkans and the Turkic countries. Ki ...
flatweave carpets, for protection from their sting. The scorpion is perceived both as an embodiment of evil and as a protective force such as a dervish's powers to combat evil. In Muslim folklore, the scorpion portrays human sexuality. Scorpions are used in folk medicine in South Asia, especially in antidotes for scorpion stings. One of the earliest occurrences of the scorpion in culture is its inclusion, as ''Scorpio (astrology), Scorpio'', in the 12 signs of the Zodiac by Babylonian astronomy, Babylonian astronomers during the Neo-Babylonian, Chaldean period. This was then taken up by western astrology; in astronomy the corresponding constellation is named Scorpius. In ancient Egypt, the goddess Serket, who protected the Pharaoh, was often depicted as a scorpion. In ancient Greece, a warrior's shield sometimes carried a scorpion device, as seen in red-figure pottery from the 5th century BC. In Greek mythology, Artemis or Gaia sent a giant scorpion to kill the hunter Orion, who had said he would kill all the world's animals. Orion and the scorpion both became constellations; as enemies they were placed on opposite sides of the world, so when one rises in the sky, the other sets. Scorpions are mentioned in the Bible and the Talmud as symbols of danger and maliciousness. The Animal tale, fable of ''The Scorpion and the Frog'' has been interpreted as showing that vicious people cannot resist hurting others, even when it is not in their interests. More recently, the action in John Steinbeck's 1947 novella ''The Pearl (novel), The Pearl'' centers on a poor pearl fisherman's attempts to save his infant son from a scorpion sting, only to lose him to human violence. Scorpions have equally appeared in western artforms including film and poetry: the Surrealism, surrealist filmmaker Luis Buñuel made symbolic use of scorpions in his 1930 classic ''L'Age d'or'' (''The Golden Age''), while Stevie Smith's last collection of poems was entitled ''Scorpion and other Poems''. A variety of martial arts films and video games have been entitled ''Scorpion King''. Since Classical era, classical times, the scorpion with its powerful stinger has been used to provide a name for weapons. In the Roman army, the Scorpio (weapon), scorpio was a torsion siege engine used to shoot a projectile.Vitruvius, ''De Architectura'', X:10:1–6. The British Army's FV101 Scorpion was an armored reconnaissance vehicle or light tank in service from 1972 to 1994. A version of the Matilda II tank, fitted with a mine flail, flail to clear Land mine, mines, was named the Matilda Scorpion. Several ships HMS Scorpion, of the Royal Navy and USS Scorpion, of the US Navy have been named ''Scorpion'' including HMS Scorpion (1803), an 18-gun sloop in 1803, HMS Scorpion (1863), a turret ship in 1863, USS Scorpion (PY-3), a patrol yacht in 1898, HMS Scorpion (1910), a destroyer in 1910, and USS Scorpion (SSN-589), a nuclear submarine in 1960. The scorpion has served as the name or symbol of products and brands including Italy's Abarth racing cars and a Montesa Honda, Montesa scrambler motorcycle. A hand- or forearm-balancing asana in modern yoga as exercise with the back arched and one or both legs pointing forward over the head in the manner of the scorpion's tail is called Vrischikasana, Scorpion pose.


Notes


References


Sources

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External links


American Museum of Natural History - Scorpion Systematics Research Group

CDC – Insects and Scorpions – NIOSH Workplace Safety and Health Topic
{{featured article Scorpions, Wenlock first appearances Extant Silurian first appearances