Scorpions are venomous arthropods of the class Arachnid and are considered relatives of the spiders, mites, ticks and harvestmen. There are approximately 1,300 species of scorpions worldwide, with 30 making Arizona their home.

Range

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, mountain pine forests, rain forest and caves.

Description

As arachnids, scorpions have mouthparts called chelicerae , a pair of pedipalps , and four pairs of legs. The pincerlike pedipalps are used primarily for prey capture and defense, but are also covered with various types of sensory hairs. The body is divided into two main regions, a cephalothorax and an abdomen . The cephalothorax is covered above by a carapace (or head shield) that usually bears a pair of median eyes and 2 to 5 pairs of lateral eyes at its front corners

The abdomen consists of 12 distinct segments, with the last five forming what most people refer to as the "tail". At the end of the abdomen is the telson, which bears a bulb-shaped structure containing the venom glands and a sharp, curved aculeus to deliver the venom.

Behavior

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. Prey are located primarily by sensing vibrations. The pedipalps have an array of fine sensory hairs called trichobothria that sense air-borne vibrations; the tips of the legs have small organs that detect vibrations in the ground.

Scorpion Venom

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 (formerly called C. sculpturatus ), 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 antivenom is available for severe cases.