Artigos Sobre Centruroides Sculpturatus Ewing 1928

The Arizona Bark Scorpion (Centruroides sculpturatus, now categorized within Centruroides exilicauda) is a small scorpion species in family Buthidae endemic to the Sonoran Desert of the southwestern United States and northwestern Mexico. It is primarily found in Arizona, USA, and Sonora, Mexico, but its range extends into the borderlands of adjacent states, including western New Mexico, southern Utah, southern Nevada (including Las Vegas), and the Colorado river habitat of eastern California1. The species is noted for being the most venomous scorpion in North America4. Due to its abundance throughout its range, it is considered a pest and is not listed as a threatened species.

Bark scorpions are light yellowish brown to brown in color. Pedipalps are elongated and thin, in contrast to thicker, shorter pincers of other scorpion species. Four pairs of jointed legs and chelicerae are present. The bark scorpion has multiple eyes, with two eyes located on the top of and from 2-5 eyes located laterally on its cephalothorax7. Despite its numerous eyes, the bark scorpion’s vision is limited, and pectines (comb-like sensory organs) located on the abdomen and fine sensory hairs on the legs assist the bark scorpion with navigation, detecting prey, and finding females for mating. Adult males of the species grow up to 8 cm in length (3.14 inches), while adult females may reach up to 7 cm (2.75 inches) 1.

Centruroides exilicauda has a distinctive venomous stinger, known as a telson, located at the end of its tail. The stinger is used for defense against predation and to paralyze prey. Known predators include birds, snakes, spiders, rodents, lizards, and other vertebrates; cannibalism by other scorpions is also common4. Domestic animals, such as cats and dogs, are known to eat the bark scorpions. The bark scorpion has a diet consisting of small insects, such as roaches, beetles, and crickets, and prefers to lie in wait and ambush prey. Although the tail contains venom that is potentially lethal to human beings, the bark scorpion is not aggressive and typically does not sting humans unless provoked, or more commonly, stepped on. Fatalities, though rare, usually occur in small pets, young children, the elderly, and immuno-suppressed or allergic individuals. The average healthy human adult typically experiences symptoms for 24-72 hours that include severe pain, coupled with nausea, vomiting, and numbness; temporary dysfunction such as convulsions or immobilization localized at the sting location may also occur2. Extreme reactions to scorpion stings are characterized by numbness, paralysis, frothing at the mouth, and shortness of breath; if an extreme reaction is observed, emergency medical care should be immediately sought due to the risk of anaphylactic shock3. An anti-venom for human usage was approved by the FDA as of August 3, 2011, and can be successful at reducing symptom severity and duration of hospitalization8. Notably, the Arizona bark scorpion is born with a finite amount of venom that is not replenished over its lifespan; therefore, stings by a juvenile are more potent and potentially more dangerous than that of an adult.

Bark scorpions are well-adapted to their desert habitat due to the layers of wax on their exoskeleton which prevent water loss. Although heat tolerant, they prefer to hide under rocks, wood piles, block fences, and tree bark during the daytime desert heat, emerging at sunset to hunt prey6. They are the only known scorpion species in the southwestern United States known to be able to climb rough surfaces, and as a result can often be found climbing walls, trees, and houses5. Bark scorpions are unable to climb smooth surfaces, such as glass. Preferred habitat includes any high-humidity area with a water source that attracts prey; the prevalence of cultivated lawns and backyard swimming pools within the bark scorpion’s range makes the micro-climates of urban desert backyards ideal scorpion habitat, and therefore bark scorpions are often found inside adjacent houses3. The likelihood of finding scorpions inside a home increases during the desert fall and winter, when outdoor prey abundance and temperatures decrease. While scorpions are solitary animals during the high heat of the Sonoran Desert summer, the colder seasonal temperatures found in the area from October to March will cause the bark scorpion to congregate in nests of 20-30 animals as they hibernate for the season; this concentrated presence around a likely heat and prey source may also increase the rate of scorpion sightings within human residences during those months.

Barks scorpions are known to live up to six years. They are a viviparous species, with the female scorpion giving birth to 25-30 scorplings at a time4. Once born, the juvenile scorpions are guided onto the mother’s back, where she protects and nurtures them until the first molting of their exoskeleton, which occurs at approximately three weeks of age. The female typically does not exhibit predatory behavior towards her young during this phase, however, if prey is scarce, infanticide by the mother may occur7.

Bark scorpions, like all scorpion species, glow brightly under ultraviolet light and moonlight. This is due to a substance located within the hyaline layer of the exoskeleton. It is unknown precisely why this capability developed, although it is thought that the florescence assists in detecting lunar cycle changes; scorpions are known to be less active during moonlit nights and full moon phases9.