Arizona Bark Scorpion, Centruroides exilicauda: The Arizona Bark Scorpion is an eight-legged, venomous invertebrate belonging to Buthidae Family. It is related to spiders, mites, ticks, and harvestmen, as well as other members of the Arachnida class. Scorpions, via fossil records, have existed for 425450 million years and are believed to have an oceanic origin.
There are roughly 1,300 species of scorpions worldwide, 90 of which are found in the United States, including 86 naturally occurring west of the Mississippi River. They are very common in Arizona and Mexico. They are most prolific and diverse in warm habitats but can be found in a wide range of environments including plains, forests, and caves. They can survive extreme changes in temperature and environment, including very arid climates. Most scorpions reach a maximum length of 2 to 3 inches
The scorpion’s body has two parts, a cephalothorax which contains the head and is covered by a shell or carapace, and the abdomen. Scorpions have a pair of eyes at the top center and two to five additional pairs at the front of the shell. They have a pair of claws used to capture prey and also during mating.
The abdomen includes the main body with four pairs of walking legs and a segmented, erectile tail ending with the telson or stinger.
The triangular sternal plate (shown below) helps distinguish the dangerous scorpions from the others.
Scorpion gestation periods vary from several months to a year-and-a-half and each brood consists of 24 to 35 young. The young are born two at a time and they immediately climb onto the mother’s back where they stay for two weeks. Scorpions do not undergo metamorphosis but they do molt five or six times before they reach maturity. They have life spans of 3 to 5 years.
Scorpions are nocturnal ambush predators feeding on all types of insects, spiders, centipedes, small lizards, snakes, mice, and other scorpions. They attack and inject venom into their prey. The venom contains potent neurotoxins that depolarize the nervous system of the victim. Scorpions are preyed upon by centipedes, tarantulas, lizards, birds, bats, and mammals.
Scorpion venom is potent enough to be dangerous to humans. It can cause severe pain and swelling at the site of the sting, numbness, frothing at the mouth, respiratory difficulties, muscle twitching, and convulsions. Death is rare in recent times. The FDA has recently given approval for clinical trials to evaluate an antivenom developed in Mexico for use in the United States.