Scorpions

General features

Scorpions are a small group of terrestrial arachnids that have stealthy and nocturnal habits. During the day they hide under rocks, logs and natural cracks, or in burrows dug by them in the substrate. They have a marked seasonal activity, and most of the time they are in their shelters, coming to the surface only to feed and reproduce. The vast majority of species are active only during the warm months, remaining in a state of lethargy the rest of the year. They are usually «stenoic» organisms, extremely limited in their ability to travel long distances, and in most cases they show fidelity to a certain type of environment. Also, since they are diggers, many species depend on the granulometry and humidity of the soil, which in turn are associated with different types of climate and vegetation.

Interesting fact: scorpions fluoresce when illuminated with ultraviolet light (UV).

Reproduction and life history

In the reproductive season, males actively seek females. When they find them, they form a couple by taking them from the pincer-like pedipalps, and perform an elaborate courtship. When they find a suitable substrate, males deposit a spermatophore (an external capsule containing sperm) and inseminate the female with it.
The females are viviparous: after a long gestation period (up to 18 months in some species!), they give birth to small live young (between 5 and 80 depending on the species), which climb onto their mother’s back. The young remain with the mother until the first molt is completed, and then they disperse. They may reach maturity in less than a year, or up to 7 years in some species. Scorpions live between 2 and 8 years although there are records of specimens that lived up to 25 years in captivity!

Food and ecological importance

Like many arachnids, scorpions do not have a sharp vision. They locate their preys following vibrations on the ground and air movement, which they detect with specialized organs. Once located, they hold their preys with their pedipalps and inject them with venom using the sting on the tip of their tails. They are active predators of insects, arachnids (including other scorpions!), other arthropods and even small vertebrates. Although they do not reach a large size, being the largest species of Argentina less than 12 centimeters long, they are extremely abundant (up to one scorpion per square meter in some areas!). These characteristics make them important links in the food chain of almost all the ecosystems of the world, especially in arid and semiarid areas, where they reach their maximum diversity and abundance.

Diversity

This order of arachnids has around 1700 species described throughout the world, and they can be found on all continents except Antarctica. In Argentina 53 species are known, which inhabit different parts of the territory, from 4500 meters in the Cordillera de los Andes to the sea level. In the province of Córdoba, 16 species can be found: 4 belonging to the family Buthidae, and 12 to the family Bothriuridae. One species, Urophonius achalensis, is endemic to Córdoba, living only in the upper zone of the Sierras Grandes (Pampa de Achala and related areas).

Dangerousness

All the species have venom, but few are venomous enough to be considered dangerous to humans. In Argentina the only dangerous scorpions belong to the genus Tityus (Family Buthidae), being the great majority of reported serious cases produced by the species Tityus trivittatus. This species is native to the Argentine northeast and Paraguay, but in recent times it has spread to the center of the country, reaching large cities such as Buenos Aires and Córdoba. It has synanthropic habits (it lives in human dwellings), and it can multiply easily due to its parthenogenetic reproduction (females give birth without the intervention of males). Tityus trivittatus has neurotoxic venom, which affects the nervous system and can cause death in young children and the elderly.

How to recognize Tityus trivittatus

In the city of Córdoba it is possible to find two species of scorpions:  Bothriurus bonariensis, nearly harmless to humans, and Tityus trivittatus, which is dangerous for children and the elderly.
Bothriurus bonariensis has thick and short pedipalps, a telson bearing one sting, and the back of the abdomen has no visible lines of different color.
Tityus trivittatus has thin pedipalps with very long and sharp tips, a telson bearing one sting and one subaculear apophysis (looking like a “double sting”), and three dark longitudinal bands on the back.

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