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Life History
Scorpions have a remarkable life history. Reproduction in scorpions is indirect. Intromission occurs via a spermatophore. The male attaches the spermatophore to the substrate while grasping the female by the pedipalps or chelicerae during a mating dance or “promenade-aux-deux”. The species-specific spermatophore catapults the sperm mass into the female gonopore when a lever is touched (a lock-and-key mechanism). Scorpions are unusual among arthropods in that all are viviparous — embryos develop within the reproductive tract and receive nourishment from maternal tissues (Francke 1982). Some are parthenogenic (Matthiesen 1962; Lourenço & Cuellar 1994, 1999). More than most other terrestrial arthropods, scorpions resemble large vertebrates in life history traits and are considered K-selected (Polis & Sissom 1990). They have very low reproductive rates in comparison to other terrestrial arthropods and are among the most long-lived. Gestation times are long (several months to more than a year) and litter sizes are often small (1-105). Young are fairly large at birth and altricial, clinging to the mother for the first few molts before dispersing. Time to sexual maturity varies from 2-8 years, depending on the species (Polis & Sissom 1990). Average longevity is around 4 years, but larger species may live 25-30 years (Polis 1990). Scorpions do not molt as adults.
Literature Cited: Francke, O.F. 1982. Parturition in scorpions (Arachnida, Scorpiones): A review of the ideas. Revue Arachnologique 4: 27–37. Lourenço, W.R. & O. Cuellar. 1994. Notes on the geography of parthenogenetic scorpions. Biogeographica 70: 19–23. Lourenço, W.R. & O. Cuellar. 1999. A new all-female scorpion and the first probable case of arrhenotoky in scorpions. Journal of Arachnology 27: 149–153. Matthiesen, F.A. 1962. Parthenogenesis in scorpions. Evolution 16: 255–256. Polis, G.A. 1990. Ecology. In: Polis, G.A. (Ed.) The Biology of Scorpions. Stanford University Press, Stanford, CA, 247–293. Polis, G.A. & Sissom, W.D. 1990. Life history. In: Polis, G.A. (Ed.) The Biology of Scorpions. Stanford University Press, Stanford, CA, 161–223.
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