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Scorpions are
predatory Predation is a biological interaction in which 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 ...
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
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 landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
. There are over 2,500 described
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
, with 22 extant (living) families recognized to date. Their
taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...
is being revised to account for 21st-century
genomic Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, ...
studies. Scorpions primarily prey on
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s and other
invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s, but some species hunt
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
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. All known species give live birth and the female cares for the young as their
exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
s harden, transporting them on her back. The exoskeleton contains
fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...
chemicals and glows under
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
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 In mathematics, a percentage () is a number or ratio expressed as a fraction of 100. It is often denoted using the ''percent sign'' (%), although the abbreviations ''pct.'', ''pct'', and sometimes ''pc'' are also used. A percentage is a dime ...
) 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 motifs are woven into
kilim A kilim ( ; ; ) is a flat tapestry-weaving, woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran and Turkey, but also in the Balkans and the Turkic countries. Kilims can be purely decorative ...
carpets for protection from their sting. Scorpius 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'' 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 pe ...
between 1175 and 1225 AD from
Old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th [2-4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ...
', or from Italian ', both derived from the Latin ', equivalent to ', which is the romanization of the Greek  – ', with no native IE etymology (cfr. Arabic '':wikt:العقرب, ʕaqrab'' 'scorpion', Proto-Germanic '':wikt:crab#Etymology_1, *krabbô'' 'crab').


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 preserve ...
s have been found in many
strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...
, including marine
Silurian The Silurian ( ) is a geologic period and system spanning 23.5 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 third and shortest period of t ...
and estuarine
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
deposits, coal deposits from the Carboniferous Period and in
amber Amber is fossilized tree resin. Examples of it have been appreciated for its color and natural beauty since the Neolithic times, and worked as a gemstone since antiquity."Amber" (2004). In Maxine N. Lurie and Marc Mappen (eds.) ''Encyclopedia ...
. Whether the early scorpions were marine or terrestrial has been debated, and while they had book lungs like modern terrestrial species, the most basal such as '' Eramoscorpius'' were originally considered as still aquatic, until it was found that ''Eramoscorpius'' had book lungs. 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, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
supercontinent. Some Palaeozoic scorpions possessed
compound eye A compound eye is a Eye, visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidium, ommatidia, which are tiny independent photoreception units that consist of a cornea, lens (anatomy), lens, and p ...
s similar to those of eurypterids. The
Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...
fossils '' Protochactas'' and '' Protobuthus'' belong to the modern clades Chactoidea and Buthoidea respectively, indicating that the
crown group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...
of modern scorpions had emerged by this time.


Phylogeny

The Scorpiones are a
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
within the pulmonate Arachnida (those with book lungs). Arachnida is placed within the
Chelicerata The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, tic ...
, a subphylum of
Arthropoda Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an exoskeleton with a cuticle made of chitin, often mineralised with calcium carbonate, a body with differentiated ( metameric) segments, and paired jointed appendages. ...
that contains
sea spider Sea spiders are marine arthropods of the class (biology), class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order (biology), order P ...
s and
horseshoe crab Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scor ...
s, alongside terrestrial animals without book lungs such as
tick Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, and species, but can become larger when engorged. Ticks a ...
s and
harvestmen The Opiliones (formerly Phalangida) are an Order (biology), order of arachnids, Common name, colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs (see below). , over 6,650 species of harvestmen have been discovered w ...
. The extinct
Eurypterida Eurypterids, often informally called sea scorpions, are a group of extinct marine 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 ...
, sometimes called sea scorpions, though they were not all marine, are not scorpions; their grasping pincers were
chelicerae The chelicerae () are the arthropod mouthparts, 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 ...
, not homologous with the pincers (second appendages) of scorpions. Scorpiones is
sister A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...
to the
Tetrapulmonata Tetrapulmonata is a Taxonomic rank, non-ranked Order (biology), supra-ordinal clade of arachnids. It is composed of the Extant taxon, extant orders Uropygi (whip scorpions), Schizomida (short-tailed whip scorpions), Amblypygi (tail-less whip scor ...
, a terrestrial group of pulmonates containing the
spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...
s and whip scorpions. 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 bec ...
s as the sister group of scorpions in the clade Panscorpiones, which together with Tetrapulmonata makes up the clade Arachnopulmonata. Cladogram of current understanding of chelicerate relationships, after Sharma and Gavish-Regev (2025): The internal
phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...
of the scorpions has been debated, but
genomic Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, ...
analysis consistently places the Bothriuridae as sister to a clade consisting of Scorpionoidea and Chactoidea. The scorpions diversified between the Devonian and the early
Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...
. 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 143.1 Mya. ...
. The Iuroidea and Chactoidea are both seen not to be single clades, and are shown as "
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
" (with quotation marks) in this 2018 cladogram.


Taxonomy

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
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 carpathicus''; the other three are dubious names. He placed the scorpions among his "Insecta aptera" (wingless insects), a group that included
Crustacea Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
, 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. Although molecular evidence and similar fossils suggests a diversifi ...
. 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''; : 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 name and ...
Arachnides for spiders, scorpions, and acari (mites and ticks), though it also contained the Thysanura, Myriapoda and parasites such as
lice Louse (: lice) is the common name for any member of the infraorder Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera was previously recognized as an order, until a 2021 genetic study determined th ...
. German
arachnologist Arachnology is the scientific study of arachnids, which comprise spiders and related invertebrates such as scorpions, pseudoscorpions, harvestmen, ticks, and mites. Those who study spiders and other arachnids are arachnologists. More narrowly ...
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 born ...
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 of
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
(numbers of species in parentheses) are: ; Order Scorpiones * Parvorder Pseudochactida Soleglad & Fet, 2003 ** Superfamily Pseudochactoidea Gromov, 1998 *** Family Pseudochactidae Gromov, 1998 (1 sp.) (Central Asian scorpions of semi-
savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...
habitats) * Parvorder Buthida Soleglad & Fet, 2003 ** Superfamily Buthoidea C. L. Koch, 1837 *** Family Buthidae C. L. Koch, 1837 (1209 spp.) (thick-tailed scorpions, including the most dangerous species) *** Family Microcharmidae Lourenço, 1996, 2019 (17 spp.) (African scorpions of humid forest leaf litter) * Parvorder Chaerilida Soleglad & Fet, 2003 ** Superfamily Chaeriloidea Pocock, 1893 *** Family Chaerilidae Pocock, 1893 (51 spp.) (South and Southeast Asian scorpions of non-arid places) * Parvorder Iurida Soleglad & Fet, 2003 ** Superfamily Chactoidea Pocock, 1893 *** Family Akravidae Levy, 2007 (1 sp.) (cave-dwelling scorpions of Israel) *** Family Belisariidae Lourenço, 1998 (3 spp.) (cave-related scorpions of Southern Europe) *** Family
Chactidae The Chactidae are a family of scorpions established by Reginald Innes Pocock in 1893. They are included in the superfamily (taxonomy), superfamily Chactoidea. Genera Chactidae contains the following genera: *''Anuroctonus'' Pocock, 1893 *''Auy ...
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 ''Superstitionia donensis'' is a species of scorpion, the only species in the genus ''Superstitionia'' and the family (biology), family Superstitioniidae. This species was discovered in Arizona in 1940 by H.L Stahnke and predominately is found i ...
Stahnke, 1940 (1 sp.) (cave scorpions of Mexico and Southwestern United States) *** Family Troglotayosicidae Lourenço, 1998 (4 spp.) (cave-related scorpions of South America) *** Family
Typhlochactidae Typhlochactidae is a family of troglomorphic scorpions native to eastern Mexico. Overview of genera Subfamily: Alacraninae * Genus ''Alacran'' Subfamily: Typhlochactinae * Genus ''Sotanochactas'' * Genus ''Stygochactas'' * Genus ''Typhlochacta ...
Mitchell, 1971 (11 spp.) (cave-related scorpions of Eastern Mexico) *** Family
Vaejovidae Vaejovidae is a family (biology), family of scorpions, currently comprising 25 genera and over 230 species, found in North America. The species of the family are found from western Guatemala, throughout Mexico, and in the United States, mostly we ...
Thorell, 1876 (222 spp.) (New World scorpions) ** Superfamily Iuroidea Thorell, 1876 *** Family Caraboctonidae 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 Latreille, 1802 *** Family Bothriuridae Simon, 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 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 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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
. 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 north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...
but were accidentally introduced by humans, and have now established a population.
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, and some of the islands in
Oceania Oceania ( , ) is a region, geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its co ...
, 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 Sheerness () is a port town and civil parish beside the mouth of the River Medway on the north-west corner of the Isle of Sheppey in north Kent, England. With a population of 13,249, it is the second largest town on the island after the nearby ...
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 its key industries include health care, retail trade, construction, oil and gas, hospitality, manufacturing and educati ...
, 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 an inventory of the global conservation status and extinction risk of biological ...
; '' Afrolychas braueri'' is classed as
critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
(2012), '' 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, inv ...
(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 landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
s, but they can be found in virtually every terrestrial
habitat In ecology, habitat refers to the array of resources, 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 manifestation of its ...
including high-elevation mountains, caves, and
intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...
s. 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° and 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, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...
, high-altitude
taiga Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. In North A ...
, and mountain tops. The highest altitude reached by a scorpion is in the Andes, for '' Orobothriurus crassimanus''. As regards microhabitats, 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,
Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...
, while others such as '' Euscorpius carpathicus'',
endemic Endemism is the state of a species being found only 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 foun ...
to the
littoral zone The littoral zone, also called litoral 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 flood ...
of rivers in Romania, occupy specialized niches.


Morphology

Scorpions range in size from the '' Typhlochactas mitchelli'' of Typhlochactidae, to the '' Heterometrus swammerdami'' 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, 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 ...
. 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. Wasps, bees and a ...
or pre-abdomen, and a narrow tail-like posterior, the
metasoma The metasoma is the posterior part of the body, or tagma (biology), 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 sy ...
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 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 tortoises, the unde ...
, eyes, chelicerae (mouth parts),
pedipalp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...
s (which have chelae, 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, which 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), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...
. As in other arachnids, the nervous system is highly concentrated in the cephalothorax, but has a long ventral nerve cord with segmented
ganglia A ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system, this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system, there a ...
which may be a primitive trait. The pedipalp is a segmented, clawed
appendage An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...
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. 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 proprioceptors,
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 b ...
s and sensory
setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...
. 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 Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
seven
somite The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryogenesis, embryonic stage of somitogenesis, along the head-to-tail axis in segmentation (biology), segmented animals. ...
s (segments) of the opisthosoma are each covered dorsally by a sclerotized plate called the tergite.
Ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. 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 ventral side of somite 1 has a pair of genital opercula covering the gonopore. 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 co ...
. 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 (: 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 * Lame ...
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 In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart a ...
. The heart is continuous with a deep arterial system which spreads throughout the body. Sinuses return deoxygenated blood ( hemolymph) 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 Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...
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 (, : 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, leaf veins, or streams. Such a connection may be ...
. 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 ger ...
formation and embryonic development. They connect to two
oviduct The oviduct in vertebrates is the passageway from an ovary. In human females, this is more usually known as the fallopian tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, or will dege ...
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; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
. 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 Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...
-based structures which come together to form the
spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...
.


Metasoma

The "tail" or metasoma consists of five segments and the telson, 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, which contains a symmetrical pair of venom 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 metalloproteins with zinc, hardening the tip. The optimal stinging angle is around 30 degrees relative to the tip.


Biology

Most scorpion species are
nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...
or
crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine (biology), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnalit ...
, 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'' 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'' 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 when the temperature drops. Some species hibernate. Scorpions are resistant to
ionizing radiation Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...
, surviving nuclear tests in Algeria and Nevada. Desert scorpions have several adaptations for water conservation. They excrete insoluble compounds such as
xanthine Xanthine ( or , from Ancient Greek for its yellowish-white appearance; 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 ...
,
guanine Guanine () (symbol G or Gua) is one of the four main nucleotide bases 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 ...
, and
uric acid Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the Chemical formula, 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 meta ...
, 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 organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...
s and waxes from epidermal glands, and protects against
ultraviolet radiation Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...
. Even when dehydrated, a scorpion can tolerate high
osmotic pressure Osmotic pressure is the minimum pressure which needs to be applied to a Solution (chemistry), solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a soluti ...
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 and
centipede Centipedes (from Neo-Latin , "hundred", and Latin , "foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', "lip", and Neo-Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, ...
s. Major
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s include frogs, lizards, snakes, birds, and mammals.
Meerkat The meerkat (''Suricata suricatta'') or suricate is a small mongoose found in southern Africa. It is characterised by a broad head, large eyes, a pointed snout, long legs, a thin tapering tail, and a brindled coat pattern. The head-and-body ...
s 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 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) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s, scuttle flies,
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s and some bacteria. The
immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
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 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'', '' Centruroides margaritatus'', 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'' 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
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...
s,
cricket Cricket is a Bat-and-ball games, bat-and-ball game played between two Sports team, teams of eleven players on a cricket field, field, at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cr ...
s,
termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...
s,
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
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 Woodlice are terrestrial isopods in the suborder Oniscidea. Their name is derived from being often found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects. Woodlice evolved from marine isopods ...
and even small
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
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 predators, 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 () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
fragments) is trapped by
seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...
e in the pre-oral cavity and ejected. The sucked-in food is pumped into the midgut by the
pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...
, 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'', and the species '' Centruroides gracilis'', '' Liocheles australasiae'', and '' Ananteris coineaui'' have been reported, not necessarily reliably, to reproduce through
parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...
, in which unfertilized eggs develop into living
embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
s. Receptive females produce
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s 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 Dance is an The arts, art form, consisting of sequences of body movements with aesthetic and often Symbol, symbolic value, either improvised or purposefully selected. Dance can be categorized and described by its choreography, by its repertoir ...
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 Sexual cannibalism is when an animal, usually the female, Cannibalism, cannibalizes its mate prior to, during, or after Copulation (zoology), copulation. This trait is observed in many arachnid orders, several insect and crustacean clades, Gastro ...
after mating has only been reported anecdotally in scorpions.


Birth and development

Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...
in scorpions can last for over a year in some species. They have two types of
embryonic development In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermat ...
; apoikogenic and katoikogenic. In the apoikogenic system, which is mainly found in the Buthidae, embryos develop in yolk-rich eggs inside follicles. The katoikogenic system is documented in Hemiscorpiidae, Scorpionidae and Diplocentridae, and involves the embryos developing in a
diverticulum In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...
which has a teat-like structure for them to feed through. Unlike the majority of arachnids, which are
oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...
, 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 molt. The period before the first molt is called the pro-juvenile stage; the young are unable to feed or sting, but have 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
instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...
s 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 of
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
light, such as that produced by a
black light A blacklight, also called a UV-A light, Wood's lamp, or ultraviolet light, is a lamp (fixture), lamp that emits long-wave (UV-A) ultraviolet light and very little visible light. One type of lamp has a violet light filter, filter material, eith ...
, due to
fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...
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 Sclerotization is a biochemical process that produces the rigid shell of sclerotin that comprises an insect's chitinous exoskeleton. It is prominent in the thicker, armored parts of insects and arachnid Arachnids are arthropods in the Class (b ...
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 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
allergies Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...
are especially at risk; otherwise,
first aid First aid is the first and immediate assistance given to any person with a medical emergency, with care provided to preserve life, prevent the condition from worsening, or to promote recovery until medical services arrive. First aid is gener ...
is symptomatic, with
analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals ...
. Cases of very high blood pressure are treated with medications that relieve anxiety and relax the blood vessels. Scorpion envenomation with high morbidity and mortality is usually due to either excessive autonomic activity and cardiovascular toxic effects, or neuromuscular toxic effects.
Antivenom Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if ...
is the specific treatment for scorpion envenomation combined with supportive measures including vasodilators in patients with cardiovascular toxic effects, and
benzodiazepine Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant, depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed t ...
s when there is neuromuscular involvement. Although rare, severe hypersensitivity reactions including
anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...
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 Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
is one of the most affected countries, with the highest
biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...
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
insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...
s 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 medical use

Scorpion venom is a mixture of neurotoxins; most of these are
peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...
s, chains of
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
s. Many of them interfere with membrane channels that transport sodium,
potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
,
calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
, or
chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...
ions. These channels are essential for nerve conduction,
muscle contraction Muscle contraction is the activation of Tension (physics), tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in musc ...
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 An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
,
antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...
, antiviral,
antiparasitic Antiparasitics are a class of medications which are indicated for the treatment of parasitic diseases, such as those caused by helminths, amoeba, ectoparasites, parasitic fungi, and protozoa, among others. Antiparasitics target the parasitic ...
,
bradykinin Bradykinin (BK) (from Greek ''brady-'' 'slow' + ''-kinin'', ''kīn(eîn)'' 'to move') is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpo ...
-potentiating, and immunosuppressive drugs. As of 2020, no scorpion toxin-based drug is for sale, though chlorotoxin is being trialled for use against
glioma A glioma is a type of primary tumor that starts in the glial cells of the brain or spinal cord. They are malignant but some are extremely slow to develop. Gliomas comprise about 30% of all brain and central nervous system tumors and 80% of ...
, a brain cancer.


Consumption

Scorpions are eaten by people in West Africa, Myanmar and East Asia. Fried scorpion is traditionally eaten in
Shandong Shandong is a coastal Provinces of China, province in East China. Shandong has played a major role in Chinese history since the beginning of Chinese civilization along the lower reaches of the Yellow River. It has served as a pivotal cultural ...
, 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 Peat is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...
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", ''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 scorpion motif (two types shown) was often woven into Turkish ''
kilim A kilim ( ; ; ) is a flat tapestry-weaving, woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran and Turkey, but also in the Balkans and the Turkic countries. Kilims can be purely decorative ...
'' flatweave carpets, for protection from their sting.
The scorpion is a culturally significant animal, appearing as a motif in art, especially in
Islamic art Islamic art is a part of Islamic culture and encompasses the visual arts produced since the 7th century CE by people who lived within territories inhabited or ruled by Muslims, Muslim populations. Referring to characteristic traditions across ...
in the Middle East. A scorpion motif is often woven into Turkish
kilim A kilim ( ; ; ) is a flat tapestry-weaving, woven carpet or rug traditionally produced in countries of the former Persian Empire, including Iran and Turkey, but also in the Balkans and the Turkic countries. Kilims can be purely decorative ...
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 Human sexuality is the way people experience and express themselves sexually. This involves biological, psychological, physical, erotic, emotional, social, or spiritual feelings and behaviors. Because it is a broad term, which has varied ...
. Scorpions are used in
folk medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...
in South Asia, especially in
antidote An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon antidoton)'', "(medicine) given as a remedy". An older term in English which is ...
s for scorpion stings. One of the earliest occurrences of the scorpion in culture is its inclusion, as '' Scorpio'', in the 12 signs of the Zodiac by Babylonian astronomers during the Chaldean period. This was then taken up by western
astrology Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions ...
; in astronomy the corresponding constellation is named Scorpius. In
ancient Egypt Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...
, the goddess Serket, who protected the
Pharaoh Pharaoh (, ; Egyptian language, Egyptian: ''wikt:pr ꜥꜣ, pr ꜥꜣ''; Meroitic language, Meroitic: 𐦲𐦤𐦧, ; Biblical Hebrew: ''Parʿō'') was the title of the monarch of ancient Egypt from the First Dynasty of Egypt, First Dynasty ( ...
, was often depicted as a scorpion. In
ancient Greece Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically r ...
, a warrior's shield sometimes carried a scorpion device, as seen in
red-figure pottery Red-figure pottery () is a style of Pottery of ancient Greece, ancient Greek pottery in which the background of the pottery is painted black while the figures and details are left in the natural red or orange color of the clay. It developed in A ...
from the 5th century BC. In
Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...
,
Artemis In ancient Greek religion and Greek mythology, mythology, Artemis (; ) is the goddess of the hunting, hunt, the wilderness, wild animals, transitions, nature, vegetation, childbirth, Kourotrophos, care of children, and chastity. In later tim ...
or
Gaia In Greek mythology, Gaia (; , a poetic form of ('), meaning 'land' or 'earth'),, , . also spelled Gaea (), is the personification of Earth. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (S ...
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 The Bible is a collection of religious texts that are central to Christianity and Judaism, and esteemed in other Abrahamic religions such as Islam. The Bible is an anthology (a compilation of texts of a variety of forms) originally writt ...
and the
Talmud The Talmud (; ) is the central text of Rabbinic Judaism and the primary source of Jewish religious law (''halakha'') and Jewish theology. Until the advent of Haskalah#Effects, modernity, in nearly all Jewish communities, the Talmud was the cen ...
as symbols of danger and maliciousness. The Sanskrit medical encyclopedia, The '' Suśrutasaṃhita'', datable to before 500 CE, contains a detailed description of thirty types of scorpion, classified according to the levels of toxicity of their stings and their colours. Treatments for scorpion-sting are described. The
fable Fable is a literary genre defined as a succinct fictional story, in prose or verse, that features animals, legendary creatures, plants, inanimate objects, or forces of nature that are anthropomorphized, and that illustrates or leads to a parti ...
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 John Ernst Steinbeck ( ; February 27, 1902 – December 20, 1968) was an American writer. He won the 1962 Nobel Prize in Literature "for his realistic and imaginative writings, combining as they do sympathetic humor and keen social percep ...
's 1947 novella '' 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
surrealist Surrealism is an art movement, art and cultural movement that developed in Europe in the aftermath of World War I in which artists aimed to allow the unconscious mind to express itself, often resulting in the depiction of illogical or dreamlike s ...
filmmaker Filmmaking or film production is the process by which a Film, motion picture is produced. Filmmaking involves a number of complex and discrete stages, beginning with an initial story, idea, or commission. Production then continues through screen ...
Luis Buñuel Luis Buñuel Portolés (; 22 February 1900 – 29 July 1983) was a Spanish and Mexican filmmaker who worked in France, Mexico and Spain. He has been widely considered by many film critics, historians and directors to be one of the greatest and ...
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 Martial arts are codified systems and traditions of combat practiced for a number of reasons such as self-defence; military and law enforcement applications; combat sport, competition; physical, mental, and spiritual development; entertainment; ...
films and video games have been entitled ''Scorpion King''. Since classical times, the scorpion with its powerful stinger has been used to provide a name for weapons. In the
Roman army The Roman army () served ancient Rome and the Roman people, enduring through the Roman Kingdom (753–509 BC), the Roman Republic (509–27 BC), and the Roman Empire (27 BC–AD 1453), including the Western Roman Empire (collapsed Fall of the W ...
, the scorpio was a torsion siege engine used to shoot a projectile.
Vitruvius Vitruvius ( ; ; –70 BC – after ) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work titled . As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissan ...
, ''De Architectura'', X:10:1–6.
The British Army's FV101 Scorpion was an armored reconnaissance vehicle or light
tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; ...
in service from 1972 to 1994. A version of the Matilda II tank, fitted with a flail to clear mines, was named the Matilda Scorpion. Several ships of the Royal Navy and of the US Navy have been named ''Scorpion'' including an 18-gun sloop in 1803, a turret ship in 1863, a patrol yacht in 1898, a destroyer in 1910, and 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 scrambler
motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...
. A hand- or forearm-balancing
asana An āsana (Sanskrit: आसन) is a body posture, originally and still a general term for a sitting meditation pose,Verse 46, chapter II, "Patanjali Yoga sutras" by Swami Prabhavananda, published by the Sri Ramakrishna Math p. 111 and late ...
in modern
yoga as exercise Yoga as exercise is a physical activity consisting mainly of asana, postures, often connected by vinyasa, flowing sequences, sometimes accompanied by pranayama, breathing exercises, and frequently ending with savasana, relaxation lying down or ...
with the back arched and one or both legs pointing forward over the head in the manner of the scorpion's tail is called Scorpion pose.


Misconceptions

It is a common misconception that a scorpion will sting itself to death if submerged in
alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...
. Another claim, that eating a scorpion will cause
hallucination A hallucination is a perception in the absence of an external stimulus that has the compelling sense of reality. They are distinguishable from several related phenomena, such as dreaming ( REM sleep), which does not involve wakefulness; pse ...
s, is also entirely false.


Notes


References


Further reading

* * *


External links


American Museum of Natural History - Scorpion Systematics Research Group

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