Figure 1, Sand Scorpion


Sand Scorpion

Class Arachnida, Order Scorpiones, Family Various

Other: Giant Hairy Scorpion (Hadrurus ssp.)

Identification/Description: Eight legs; stinger at end of telson, Kaufman, p. 24. “The scorpion's body has two parts, a cephalothorax which contains the prosoma, or head; and the abdomen. The cephalothorax is covered by the carapace, a hard bony or chitinous outer covering. The carapace usually suports [sic] a pair of median eyes at the top center. Two to five pairs of lateral eyes are found at the front corners of the carapace, though a few cave and montane forest litter-dwelling scorpions are eyeless. Chelicerae, the scorpion's mouthparts, and a pair of pedipalps, or claws used for prey capture and mating complete the head anatomy. The pedipalps are covered with trichobothria, sensory setae, that sense air-borne vibrations. The abdomen is made up of the mesosoma, the main body, and the metasoma, the tail. The mesosoma, protected by bony armour, contains the lungs, digestive organs and sexual organs, as well as bearing 4 pairs of walking legs and the pectines. The tips of the legs have small organs that detect vibrations in the ground. The pectines are feathery sensory organs which hang beneath the abdomen and trail on the ground. They are coated by chemosensors that provide detection of minute chemical signals that are thought to alert the scorpions to the approach of prey and also to be of use in mating behavior. The respiratory structure, known as "book lungs," are spiracles that open into the scorpion's body. The surfaces of the legs, pedipalps, and body are also covered with thicker hairs that are sensitive to direct touch. The metasoma curves up and ends in the telson, which bears the bulbous vesicle containing the venom glands and a sharp, curved aculeus which delivers the venom,” according to “Scorpions” at  Real advances in systematics will come with the adoption of the scanning electron microscope (SEM), according to Brewer (2007).



Length: 2-3 inches at adulthood; average 6 centimeters.


Metamorphosis/Immature Stages:  Simple/gradual.  “Females give live birth, and the babies ride on mom’s back [for 5-15 days] until their first molt,” Kaufman, p. 24 and “The Best Control.” The fist instar, between 7-17 days, does not fluoresce (Polis and Mohnac, 1990).  Gestation five months to a year with up to thirty young at birth, which will then molt six or seven times.  Parthenogenesis possible.


Life Cycle:  “Males and females find each other by vibration, scent and touch,” according to ScorpionFacts.  Three-to-four/seven years to maturity.  They can live 3, 15-25 years, according to “The Best Control for Scorpions.”


Food: Waiting in ambush due to their poor eyesight, they eat “all types of insects, spiders, centipedes, and other scorpions.  They capture their prey with their pedipalps, paralyzing them with their venom as well if necessary. The immobilized prey is then subjected to an acid spray that dissolves the tissues, allowing the scorpion to suck up the remains,” according to DesertsUSA. According to Insects of the LA Basin (1993), they prefer soft-bodied insects [including] …beetles, cockroaches, crickets, centipedes, spiders, sun spiders, and other ground dwellers.”

Prevenom (containing less protein but more K+ ions) to induce pain has been identified by Ahmet B. Inceoglu (UC Davis, PhD, 2002).  Neurotoxins (up to 20 or more; today, more than 200 known) in the venom contain about 60-70 amino acids cross-linked by four disulfide bridges (see Suddath et al., 1982).  Extremely low metabolism; supposedly can withstand starvation for 4-5 months, according to “Safe Controls” at Best Solutions.


Lethal Food Plants:  “Around 300 BC, Theophrastus, in book 9 of his Enquiry to Plants, noted that wolfsbane, or scorpion plant (Aconitum anthora) kills scorpions if it is shredded over them.  Pliny in book 20 of his Natural History, written in the first century A.D. advised that a mallow leaf (Malva) placed on a scorpion paralyzes it," according to “Safe Controls for Scorpions.”

Habitat: During the day, “under stones or bark,” Kaufman, p. 24.  In danger, other animal burrows; but, they prefer their own long, cork-screwing vertical tunnel burrows (BBC Video, 2006).


Behavior:  Nocturnal; navigation by starlight; sluggish at temperatures below 70° F and avoid temperatures over 100 F°, according to “The Best Control.”  24-36 hour courting/mating dance ritual with pedipalps.  Although they can see in the UV range and controlled by the SWS1 gene, prey location is accomplished by non-visual cues (i.e., sound waves in sand): “One sensor, called the basitarsal slit sensillum, detects the surface wave propagated by sand, while others--the numerous sensory hairs touching the surface--are more responsive to compressional waves,” according to Brownell and van Hemmen, 2000.


Interest/Importance: Only the Arizona species (Centruroides) has venom strong enough to be lethal or cause “severe local skin reaction, neurologic collapse, respiratory collapse, cardiovascular collapse, respiratory failure, [or] cardiovascular failure”, according to eMedicine.  Anti-venom from ASU is not CDC approved; Instituto Bioclon of Mexico trials under way in 2004.  Otherwise, scorpion venom has pharmacological utility in VGSC, cystic fibrosis, or novel drug delivery pathways.


Number of Species: Worldwide, about 1300; North American, about 90 (“Southern Nevada, southeastern California, and central Arizona with highest diversity,” Polis and Sissom, 1990); and only 25-50 dangerous to humans and all are in the Buthidae family.


Ancestry:  “the only land animals with a fossil record stretching back to the colonization of land by aquatic animals,” according to Polis and Sissom, 1990. 


Range: Southwestern US; north into British Columbia; Virginia, Kentucky and Missouri; and northern Florida.


Did You Know: The scorpion is the only insect in the Zodiac or that UV fluorescence of scorpions was first reported in 1954?  According to Walter Reed, “The [bright blue-green] fluorescence is caused by an unidentified substance [hypothesized by Fasel et al. as a flavin or flavone and confirmed by Wankhede, 2004 as beta carboline, a neuroprotective, and 7-hydroxy-4-methylcoumarin which is used as an optical brightener] in a very thin layer in the cuticle of the scorpion called the hyaline layer.  Newly molted scorpions do not fluoresce.  As the new cuticle hardens, the fluorescent quality increases.  This [condition] indicates that the fluorescent factor is either secreted by the scorpion shortly after molting or that the fluorescence is a by-product of the tanning process.  Alcohol in which scorpions have been preserved may also fluoresce.  The hyaline layer of the cuticle is very tough stuff.  It is often found in scorpion fossils.  Even after hundreds of millions of years, while all the other layers of the cuticle have been lost, this hyaline layer remains embedded in fossil rocks. And yes, it still fluoresces.  Nobody knows the function of the hyaline cuticle or its strange fluorescence.  Some have suggested that it serves as UV sensor (all scorpions are basically nocturnal and shun the light).” 




Michael Brewer, “New Microanatomical Characters for Scorpion Taxonomy (Arachnida: Scorpiones),’ MS Thesis, Marshall University, 2007.


Philip H. Brownell and J. Leo van Hemmen, “How the Sand Scorpion Locates Its Prey,” at (accessed 20 May 2008).


“Chapter 25: The Best Control for Scorpions” at (accessed 19 May 2008).


A. Fasel; P.-A. Muller, P. Suppan, and E. Vauthey, “Photoluminescence of the African Scorpion ‘Pandinus Imperator’,” Journal of Photochemistry and Photobiology 39 (1997): 96-98.


Charles L. Hogue, Insects of the Los Angeles Basin, Los Angeles: Natural History Museum of Los Angeles County, 1993, pp. 357-358.


Kaufman Field Guide to Insects of North America (2007).


Gary A. Polis and Mark Mohnac, “Mating by Female Scorpions While Still Carrying Young,” Journal of Arachnology 18 (Autumn 1990): 363-364.


“Safe Controls for Scorpions” at (accessed 19 May 2008).


Scorpion Facts,” at (accessed 19 May 2008).


“Scorpion Sting” at (accessed 19 May 2008).


“Scorpions” at (accessed 19 May 2008).


F. L. Suddath, Charles E. Bugg, Steven A. Ealick, Robert J. Almassy, and Juan C. Fontecilla-Camps, “The 1.3-Å Structure of a Scorpion Neurotoxin: A Membrane-binding Protein,” Biophysical Journal 37 (January 1982): 185-186.


Walter Reed Biosystematics Unit, “What Causes Scorpions to Fluoresce?” at (accessed 19 May 2008).


Ravi A. Wankhede, “Extraction, Isolation, Identification and Distribution of Soluble Fluorescent Compounds from the Cuticle of Scorpion (Hadrurus arizonensis),” MS Thesis, Marshall University, 2004 at (accessed 21 May 2008).


Other References:


Philip Brownell and Gary A. Polis, Scorpion Biology and Research.  Oxford: Oxford University Press, 2001.


Thomas Eisner, Maria Eisner, and Melody Siegler, Secret Weapons: Defenses of Insects, Spiders, Scorpions and Other Many-Legged Creatures.  Cambridge, MA: Belknap Press of Harvard University Press, 2005.


Gary A. Polis and W. David Sissom, “Life History,” In Biology of Scorpions, edited by G.A. Polis.  Palo Alto: Stanford University Press, 1990.


“Scorpions” at (accessed 22 May 2008).



FIELD NOTES: Saturday evening as well as Sunday morning, 15-16 May 2008, Desert Studies Center, Zzyzx, California.