Scorpions

Scorpions are venomous arthropods of the class Arachnida and are considered relatives of the spiders, mites, ticks and harvestmen.  There are approximately 1,300 species of scorpions worldwide, characterized by an elongated body and a segmented tail that is tipped with a venomous stinger.  Scorpions are commonly thought of as desert animals, but in fact, they occur in many other habitats as well, including grasslands and savannahs, deciduous forests, rain forest and caves.   About 90 species occur in the U.S., and all but four of these naturally occur west of the Mississippi River.

Scorpions are nocturnal, predatory animals that feed on a variety of insects, spiders, centipedes, and other scorpions.  The larger scorpions occasionally feed on vertebrates, such as smaller lizards, snakes, and mice.  Scorpions have a complex mating ritual and have a long gestation period (from several months to a year and a half, depending on species).  On the average, a female gives birth to about 25-35 young. They remain on her back until they molt for the first time, usually within a week or two after birth.  Once they climb down, they assume an independent existence, and periodically molt to reach adulthood.  The average scorpion probably lives three to five years, but some species undoubtedly live up to 15 years.

The venom of scorpions is used for both prey capture and defense.  Scorpion venoms are complex mixtures of neurotoxins (toxins which affect the victim's nervous system) and other substances; each species has a unique mixture. Despite their bad reputation, only one species in the U.S. and about 20 others worldwide have venom potent enough to be considered dangerous to humans.

The US species, Centruroides exilicauda is found over much of Arizona.  A small population occurs in extreme southeastern California, and a few records exist for southern Utah.  The venom of this scorpion may produce severe pain and swelling at the site of the sting, numbness, frothing at the mouth, difficulties in breathing (including respiratory paralysis), muscle twitching, and convulsions.  Death is rare, especially in more recent times.  An antivenin is available for severe cases.

The world's most dangerous scorpions live in North Africa and the Middle East, South America, India and Mexico.  In some of these areas, scorpion stings may be a significant cause of death, but reliable data on human mortality are not readily available.  Some available statistics suggest typical mortality rates up to about 4% in hospital cases, with children and the aged being most susceptible.

Death by scorpion sting, if it occurs, is the result of heart or respiratory failure some hours after the incident.