Hadrurus arizonensis

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Geographic Range

North American hairy scorpions are native to desert regions of the Nearctic, largely within the Sonoran and Mojave desert in the southwestern United States. They can also be found in Utah and Nevada. ("Giant Desert Hairy Scorpion", 2010)

Habitat

North American hairy scorpions are generally found within the Sonoran and Mojave deserts. They occupy abandoned burrows, small caves, and crevices. They can also be found in suburban environments in California and Arizona, where they seek out ornamental plants and irrigated lawns that attract beetles and other invertebrate prey. North American hairy scorpions are generally found at 900 to 1800 m in elevation. (Gefen, et al., 2009; Natwick, 2011; )

  • Range elevation
    900 to 1800 m
    2952.76 to 5905.51 ft

Physical Description

North American hairy scorpions are the largest scorpions in North America. They measure 10 to 18 cm in length (average 15 cm) and weigh 4 to 7 g (average 5 g). North American hairy scorpions are named for the small erect hairs located on their tail. Males and females are very similiar in appearance, and they are usually tan to olive-green in color, with a darker back and yellow pedipalps, legs, and tail. Their basal metabolic rate ranges from 0.3 to 0.525 cm^3 oxygen/hour (average 0.375). North American hairy scorpions are ectothermic, heterothermic, and venomous. (Hadley, 1970)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    4 to 7 g
    0.14 to 0.25 oz
  • Average mass
    5 g
    0.18 oz
  • Range length
    10 to 18 cm
    3.94 to 7.09 in
  • Average length
    15 cm
    5.91 in
  • Range basal metabolic rate
    .3 to .525 cm3.O2/g/hr
  • Average basal metabolic rate
    .375 cm3.O2/g/hr

Development

North American hairy scorpions give birth to live young. The body of North American hairy scorpions remains unchanged in structure as it develops, only increasing in size as it molts. On average, they molt 4 to 6 times before reaching adulthood in about 4 years. (Tallarovic, et al., 2000; "Giant Desert Hairy Scorpion", 2010)

Reproduction

Like most scorpions, North American hairy scorpions mate in a multi-step process. Males generally instigate breeding, although females have also been observed initiating mating. When two receptive scorpions encounter one another, the male shows his presence by rocking and jarring back and forth. The male grabs the female by the side, clubbing the mesosoma of the female with the stinger, inflicting up to 14 "sexual stings" on the back of the female. He then grabs the female by the pedipalps, leading her on a "promenade a deux", a coordinated dance involving simple movements back and forth rocking until the two find a suitable substrate on which to mate. Once the "promenade" is complete, the male deposits a spermatophore on the substrate. The male pulls the female over the spermatophore, causing the sperm to be released into her gonophore, completing fertilization. Upon termination of the mating process, the male may club the female again before releasing its grip and returning to the wild. Females are not always receptive to mating and often resist the male after he deposits the spermatophore in order to avoid accepting the sperm into her abdomen. Occasionally, after mating, the female tracks down her mate and eats it. Because this species is very solitary, there are no social structures involved in mating. (Tallarovic, et al., 2000; "Giant Desert Hairy Scorpion", 2010)

North American hairy scorpions breed opportunistically at night. There is no defined breeding season, although they become dormant in the winter months and likely do not breed at that time. North American hairy scorpions reproduce sexually following an intricate mating behavior. Gestation is unusually long, a period of 6 to 12 months (average 10 months). Females give birth to a large litter of 25 to 35 individuals (average 30). Young are small, white, and vulnerable at birth, and immediately crawl to their mother's back. They are carried on their mother's back for 3 weeks, until the young have molted at least once and can live independently. North American hairy scorpions reach adulthood in about 4 years. (Natwick, 2011; Tallarovic, et al., 2000; )

  • Breeding season
    North American hairy scorpions breed year round, except when dormant during winter months.
  • Range number of offspring
    25 to 35
  • Range gestation period
    6 to 12 months
  • Average gestation period
    10 months
  • Range time to independence
    1 to 3 weeks

Male North American hairy scorpions do not provide parental care to their young and are occasionally cannibalized by their female mate after fertilization. Mothers carry their young on their back for 1 to 3 weeks, until they have molted at least one. This helps young regulate temperature and moisture levels, as they have not yet fully developed an epicuticle to do so independently. (Tallarovic, et al., 2000)

  • Parental Investment
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

North American hairy scorpions are the longest-lived species of scorpions, often living for over 20 years in captivity. They typically live 7 to 10 years in the wild and 15 to 20 years in captivity. ("Giant Desert Hairy Scorpion", 2010)

  • Range lifespan
    Status: captivity
    25 (high) years
  • Typical lifespan
    Status: wild
    7 to 10 years
  • Typical lifespan
    Status: captivity
    15 to 20 years

Behavior

North American hairy scorpions are solitary predators that spend most of their time in burrows or under rocks. They are nocturnal, and utilize natural features such as rocks for protection from the sweltering heat during the day. They often use caves as a temperature-regulated habitat. Caves are also dark and occupied by many of their food sources. North American hairy scorpions go dormant during the winter as temperatures drop, often living underground in their burrow or in caves. North American hairy scorpions are not territorial. However, they attack and defend themselves when provoked, raising their legs and orienting themselves vertically, striking blindly at anything deemed threatening. (Hadley and Williams, 1968; ; "Giant Desert Hairy Scorpion", 2010)

Home Range

Home ranges of North American hairy scorpions vary with distance between suitable burrows and ambush spots for prey. They do not appear to make a permanent home, and distance traveled in search of food is not consistent. (Hadley and Williams, 1968; "Giant Desert Hairy Scorpion", 2010)

Communication and Perception

There is little evidence of social communication among North American hairy scorpions, although communication does play a large role in mating. Males utilize a variety of dances and repetitive motions to initiate mating. Females have also been observed signaling males when they are receptive or willing to mate. In a laboratory setting, North American hairy scorpions used chemical signals to trail a potential mate or to leave a trail or suggestive sent marks. North American hairy scorpions utilize their hairs, for which they are named, to detect vibrations in the air (sound) as well as in the ground. (Tallarovic, et al., 2000; Mellville, et al., 2003)

Food Habits

North American hairy scorpions are carnivorous, often preying on organisms of comparable size, such as insects and other invertebrates, lizards and small mammals. Other scorpions comprise a significant portion of their diet, leading to intense competition among scorpion species in their habitat. North American hairy scorpions are solitary active predators. They often wait inside a burrow and ambush prey with their stinger once prey are in range. They use their modified front pedipalps to grab prey and the stinger equipped to their tail to deliver a venomous sting. The venom of North American hairy scorpions is fairly week compared to most scorpions. The venom successfully immobilizes small insects and other invertebrates but has little effect on vertebrates such as lizards and small mammals. They fight for their meal if prey struggle. North American hairy scorpions are cannibalistic in laboratory settings, although this is notably less frequent in the wild, where food is much more abundant. (Polis and McCormick, 1987; Hadley and Williams, 1968; "Giant Desert Hairy Scorpion", 2010)

  • Animal Foods
  • mammals
  • reptiles
  • insects
  • terrestrial non-insect arthropods

Predation

North American hairy scorpions have considerable fat reserves, making them ideal prey for medium-sized vertebrates. Their most common predators are large lizards and owls. They are also preyed upon by other scorpions, both for food and to assert dominance. When threatened, North American hairy scorpions stand erect on their legs and flail their stinger, attempting to dissuade or attack predators. They are also colored to blend in with some of their habitat, although this is not true camouflage as they often live in dark areas out of view from predators. (Ramel, 1999)

Ecosystem Roles

North American hairy scorpions eat a variety of insects, scorpions, lizards, and small vertebrates and are preyed upon by other scorpions, lizards, and owls. They also compete with many other genera of scorpions. North American hairy scorpions also act as hosts to some parasitic mites, such as Pimeliaphilus, which are sanguivorous ectoparasites. (Polis and McCormick, 1987; Beer, 1960)

Commensal/Parasitic Species
  • mites Pimeliaphilus

Economic Importance for Humans: Positive

North American hairy scorpions are often kept as pets due to their long lifespan, hardiness, weak venom, and wide range of diet. Many pet scorpions live long healthy lives without much maintenance. ("Giant Desert Hairy Scorpion", 2010)

Economic Importance for Humans: Negative

Although North American hairy scorpions sting humans, their venom is weak and they are not considered a public health threat. Their sting is comparable to a bee sting. North American hairy scorpions are also considered a house pest in suburban areas of the desert southwestern United States, where they may inhabit cool dry and dark places of houses, such as kitchen cabinets, crawl spaces, and attics. (Natwick, 2011; )

  • Negative Impacts
  • injures humans
    • bites or stings
  • household pest

Conservation Status

The conservation status of North American hairy scorpions has not been evaluated by the IUCN. The species is not protected by the U.S. Endangered Species Act or the CITES international treaty.

Contributors

Joe Steinfeld (author), Rutgers University, David Zemel (author), Rutgers University, David V. Howe (editor), Rutgers University, Gail McCormick (editor), Animal Diversity Web Staff.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

terrestrial

Living on the ground.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

vibrations

movements of a hard surface that are produced by animals as signals to others

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

theBIGzoo. 2010. "Giant Desert Hairy Scorpion" (On-line). The Big Zoo. Accessed November 12, 2010 at http://www.thebigzoo.com/Animals/Giant_Desert_Hairy_Scorpion.asp.

Beer, R. 1960. A New Species of Pimeliaphilus (Acarina: Pterygosomidae) Parasitic on Scorpions, with Discussion of Its Postembryonic Development. The Journal of Parasitology, 46/4: 433-440. Accessed November 18, 2010 at http://www.jstor.org/pss/3275133.

Gefen, E., C. Ung, A. Gibbs. 2009. Partitioning of transpiratory water loss of the desert scorpion. Journal of Insect Physiology, Volume 55, Issue 6: 544-548. Accessed September 09, 2013 at http://dx.doi.org/10.1016/j.jinsphys.2009.01.011.

Hadley, N. 1970. Water Relations of the Desert Scorpion, Hadrurus arizonensis. Journal of Experimental Biology, 53: 547-558. Accessed November 15, 2010 at http://jeb.biologists.org/cgi/reprint/53/3/547.

Hadley, N., S. Williams. 1968. Surface Activities of Some North American Scorpions in Relation to Feeding. Ecology, 49/4: 726-734. Accessed November 16, 2010 at http://www.jstor.org/stable/1935535.

Mellville, J., S. Tallarovic, P. Brownell. 2003. Evidence of Mate Trailing in the Giant Hairy Desert Scorpion, Hadrurus arizonensis (Scorpionida, Iuridae). Journal of Insect Behavior, 16/1: 97-115. Accessed November 18, 2010 at http://www.ingentaconnect.com/content/klu/joir/2003/00000016/00000001/00462150.

Natwick, E. 2011. "Pest Notes: Scorpions" (On-line). UC IPM online. Accessed September 09, 2013 at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74110.html.

Polis, G., S. McCormick. 1987. Intraguild Predation and Competition Among Desert Scorpions. Ecology, 68/2: 332-343. Accessed November 18, 2010 at http://www.jstor.org/stable/1939264.

Ramel, G. 1999. "The Scorpions" (On-line). The Earthlife Web. Accessed November 18, 2010 at http://www.earthlife.net/chelicerata/scorpionidae.html.

Tallarovic, S., J. Mellville, P. Brownell. 2000. Courtship and Mating in the Giant Hairy Desert Scorpion, Hadrurus arizonensis (Scorpionida, Iuridae). Journal of Insect Behavior, 13/6: 827-838. Accessed November 15, 2010 at http://www.springerlink.com/content/q7l3tq1277564031/.