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Schizomida, also known as sprickets or short-tailed whip-scorpions,The American Arachnological Society Committee on Common Names of Arachnids (2025). 9781929427116, American Tarantula Society. . ISBN 9781929427116 is an order of , generally less than in length. The order is not yet widely studied. E. O. Wilson has identified schizomids as among the "groups of organisms that desperately need experts to work on them."
About 300 species of schizomids have been described worldwide, most belonging to the Hubbardiidae family. A systematic review including a full catalogue may be found in Reddell & Cokendolpher (1995). The Schizomida is sister to the order Uropygi, the two together forming the Thelyphonida (in the broad sense of the name). Based on molecular clock dates, both orders likely originated in the late Carboniferous somewhere in the tropics of Pangaea, and the Schizomida underwent substantial diversification starting in the Cretaceous. The oldest known fossils of the group are from the Mid-Cretaceous Burmese amber of Myanmar, which are assignable to the Hubbardiidae.
The opisthosoma (abdomen) is a smooth oval of 12 recognizable segments. The first is reduced and forms the pedicel, while the last three are constricted, forming the pygidium. The last segment bears a short whip-like tail or flagellum, consisting of no more than four segments. The females generally have three- or four-segmented flagella, while in males it is single segmented. (2025). 9780195172348, Oxford University Press. ISBN 9780195172348
Like the related orders Uropygi and Amblypygi, and the more distantly related Solifugae, the schizomids use only six legs for walking, having modified their first two legs to serve as sensory organs. They also have large well-developed pincer-like just before the sensory legs. The hind legs are modified for jumping, as part of their escape response when threatened.Humphreys, W.F., et al. (1989) The biology of Schizomus vinei (Chelicerata: Schizomida) in the caves of Cape Range, Western Australia. J. ZOol. Lond. 217: 177-201.
Schizomids have no actual eyes, but a few species have vestigial eyespots capable of telling light from dark. They breathe through a single pair of book lungs located on the second abdominal segment, as the second pair on third abdominal segment found in the other orders of Tetrapulmonata is lost.
Humidity is vital to determining the habitats in which sprickets can live as they need to avoid desiccation. They typically live in rainforest leaf litter, particularly in the top layer of organic soil, under rocks, in and beneath rotten logs, and even in troglobites. Although most species are restricted to rainforests, they can also be found in neighboring woody areas. The Australian species Draculoides vinei is believed to have been forced to move into a nearby humid cave system after its original forests dramatically decreased in size. Additionally, some species have been found in insect nests; Afrozomus machadoi lives in , while Stenochrus portoricensis has been found in ant colonies. Schizomids are also occasionally found living in the trees; the South American Surazomus arboreus lives in rainforest that is seasonally flooded, forcing the arachnids to move higher into the trees to avoid drowning.
While sprickets are not typically found in colder climates, several Californian Hubbardia species have been found living under snow-covered rocks, and Hubbardia briggsi in particular is often found in snowy habitats during the winter.
Schizomids can survive a long time without food; some Hubbardia pentapeltis have been shown to survive five months without food.
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