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.

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.

A classical myth about Scorpius tells how the giant scorpion and its enemy Orion became constellations on opposite sides of the sky.

Arachnida is placed within the Chelicerata, a subphylum of Arthropoda that contains sea spiders and horseshoe crabs, alongside terrestrial animals without book lungs such as ticks and harvestmen.

[18] In 1801, Jean-Baptiste Lamarck divided up the "Insecta aptera", creating the taxon Arachnides for spiders, scorpions, and acari (mites and ticks), though it also contained the Thysanura, Myriapoda and parasites such as lice.

[29][27] Five colonies of Euscorpius flavicaudis have established themselves since the late 19th century in Sheerness in England at 51°N,[30][31][32] while Paruroctonus boreus lives as far north as Red Deer, Alberta, at 52°N.

[34][35][36] Scorpions are xerocoles, meaning they primarily live in deserts, but they can be found in virtually every terrestrial habitat including high-elevation mountains, caves, and intertidal zones.

Some species, such as Vaejovis janssi, are versatile and are found in all habitats on Socorro Island, Baja California, while others such as Euscorpius carpathicus, endemic to the littoral zone of rivers in Romania, occupy specialized niches.

[a] The opisthosoma is subdivided into a broad anterior portion, the mesosoma or pre-abdomen, and a narrow tail-like posterior, the metasoma or post-abdomen.

[44] The cephalothorax comprises the carapace, eyes, chelicerae (mouth parts), pedipalps (which have chelae, commonly called claws or pincers) and four pairs of walking legs.

[48] 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.

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.

[67] Most scorpion species are nocturnal or crepuscular, finding shelter during the day in burrows, cracks in rocks and tree bark.

[70][71] Scorpions can withstand intense heat: Leiurus quinquestriatus, Scorpio maurus and Hadrurus arizonensis can live in temperatures of 45–50 °C (113–122 °F) if they are sufficiently hydrated.

[78][79] Other predators adapted for hunting scorpions include the grasshopper mouse and desert long-eared bat, which are also immune to their venom.

[83] A few scorpions, such as Parabuthus, Centruroides margaritatus, and Hadrurus arizonensis, squirt venom in a narrow jet as far as 1 meter (3.3 ft) to warn off potential predators, possibly injuring them in the eyes.

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.

[62] The pair then make contact using their pedipalps, and perform a dance called the promenade à deux (French for "a walk for two").

[90][91] 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.

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 through.

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.

[99] Juvenile stages or instars generally resemble smaller versions of adults, with fully developed pincers, hairs and stingers.

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.

[107] Scorpion stings are a public health problem, particularly in the tropical and subtropical regions of the Americas, North Africa, the Middle East and India.

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.

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.

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.

[124] 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.

[145] The scorpion has served as the name or symbol of products and brands including Italy's Abarth racing cars[146] and a Montesa scrambler motorcycle.