Scorpions are primarily nocturnal. All fluoresce under long-wave ultraviolet light, facilitating their collection and observation at night (Honetschlager 1965; Stahnke 1972; Lamoral 1979; Sissom et al. 1990). Their simple eyes detect luminosity, but little else (Fleissner 1977). Prey are detected with slit sense organs in the tarsi, sensory setae (trichobothria) on the pedipalps, and the pectines, and attacked with the chelate pedipalps or venomous sting. Scorpions with slender pedipalps are prone to sting their prey, those with robust pedipalps to crush prey mechanically, reserving the sting for large or strong prey. All use the pedipalps to manipulate prey, tearing pieces off with the chelicerae to be digested in a pre-oral cavity before being sucked into the gut. Scorpions are important consumers in some communities. Scorpio maurus was reported to eat an annual average of 11% of the Israeli isopod population (Shachak & Brand 1983), Urodacus yaschenkoi 7.9 kg/ha of invertebrate prey in Australia (Shorthouse & Marples 1982). Cannibalism and predation by other scorpion species may be the most important sources of scorpion mortality but other invertebrate predators (e.g. centipedes) and vertebrates are also important predators. Mortality is highest immediately after birth, lower for individuals of intermediate age, and high for adults. For example, 65%, 30%, and 60% per year for the Australian Urodacus manicatus (Smith 1966). Mortality is particularly high among males due to increased mobility during breeding season and cannibalism by females. Biased adult sex ratios of 1.2-1.4:1 are typical (Polis 1990). Social behavior occurs rarely in species of Heterometrus, Opisthacanthus and Pandinus, in which family groups with overlapping generations cooperate to construct and occupy communal burrows, inhabited by individuals of various ages (Polis & Lourenço 1986).
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Lamoral, B.H. 1979. The scorpions of Namibia (Arachnida: Scorpionida). Annals of the Natal Museum 23: 497–784.
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Shachak, M. & Brand, S. 1983. The relationship between sit-and-wait foraging strategy and dispersal in the desert scorpion Scorpio maurus palmatus. Oecologia 60: 371–377.
Shorthouse, D.J. & Marples, T. 1982. The life stages and population dynamics of an arid zone scorpion Urodacus yaschenkoi (Birula, 1903). Australian Journal of Ecology 7: 109–118.
Sissom, W.D., Polis, G.A. & Watt, D.D. 1990. Field and Laboratory Methods. In: Polis, G.A. (Ed.) The Biology of Scorpions. Stanford University Press, Stanford, CA, 445–461.