Scorpions are similar in appearance to large insects, but, because they have eight legs, are actually members of the arachnid class of the arthropod phylum, and as such are part of the same grouping that includes spiders, ticks and mites. Members of the Scorpionida order are characterized by a hollow, curved, venom-filled stinger at the tip of their metasoma, referred to commonly as their tail. Scorpions sting and kill their prey with this venom.
Scorpions have long been of interest to humans primarily because of their ability to give painful and sometimes life threatening stings. Scorpions are also an important and beneficial component of many ecosystems and they are one of the oldest known terrestrial arthropods. Fossil scorpions found in Paleozoic strata 430 million years old appear very similar to present day species.
Dating back over 400 million years to the Silurian period, scorpions are represented today by thirteen recognized families. While some 1400 species and subspecies of scorpions have been described, only a small fraction are ever capable of killing medium-sized animals, and of those only 25 are known to be capable of killing humans. Scorpions mainly inhabit certain tropical and subtropical regions of the world, and are most commonly, although by no means exclusively, associated with desert biomes. Some species survive in temperate regions as well. Most scorpions range in size from 1 to 3 inches in length, the smallest species reach only about 1/2 inch, while the largest may grow to 6 inches. Scorpions are largely nocturnal, hiding in crevices or burrows or under objects during the day. Emerging mainly at night to feed, most scorpions prey on other arthropods, including insects and other small arthropods.
Classification of a Scorpion
Where are Scorpions Found
Scorpions are commonly thought of as desert animals, but in fact, they occur in many other habitats, including grasslands and savannahs, deciduous forests, montane pine forests, intertidal zones, rain forest and caves. Scorpions have even been found under snow-covered rocks at elevations of over 12,000 feet in the Himalayas of Asia.
How Toxic is Scorpion Venom
The largest prey normally killed by scorpions includes small lizards and mice. Regardless of the size of the scorpion, all Scorpionida venom is considered neurotoxic to some degree. This means that the scorpion can disable, and sometimes kill its prey using only its venom. Neurotoxic chemicals, when they enter the bloodstream of an animal, damage the nervous system, usually by disabling and/or killing neurons. Scorpion venom can thus incapacitate the various physiological systems in its victims, including the muscular, digestive and cardiovascular systems, and can even destroy brain cells.
The wound that results from the sting of one of the more venomous scorpion species usually results in considerable pain to human adults, and small children and the elderly are particularly susceptible to the venom.
Susceptibility to scorpion venom varies greatly between victim species. For instance, for “Latrodectus mactans tredecimgutttatus” venom, one study showed that half of guinea pigs tested died at dosage levels of only 0.075 mg/kg of body weight. On the other hand, it took 2.7 mg/kg of body weight, or 36 times more venom for the same body weight, to kill half of the cockroaches tested.
Symptoms of a Scropion Sting
Convulsions and seizures have been observed both in humans and in animals as a result of scorpion stings, and they are among the most troubling signs of serious neurotoxic poisoning. Convulsions are sometimes preceded or accompanied by trouble swallowing and/or breathing, blurred vision, increased salivation and/or swollen tongue. Among the most serious symptoms that accompany convulsions or seizures are sudden and drastic rises or drops in blood pressure, diarrhea, vomiting, heart palpitations and metabolic shock.
Certain milder symptoms can serve as warning signs that the nervous system has been attacked with neurotoxic venom. These include numbness and muscle twitching, including abnormal twitching of the eyes, neck and head, and can precede convulsions or persist as aftereffects when the highest level of toxicity has passed. The most severe cases of scorpion poisoning can result in a fading or total loss of consciousness, usually due to circulatory shock, in which the effective volume of blood is reduced. Shock can lead to a lowered amount of oxygen delivered by the arteries, as well as cardiac arrest.
An animal or human bitten by a spider will commonly exhibit several of these symptoms, including convulsions which, if left untreated, can result in death.