Although scorpions have two eyes on the top of their head often 2 to 5 pairs of eyes on the front corners of their head, they do not have good vision. Scorpions, including deathstalkers, utilize their sense of touch to navigate and hunt, using their pectines and other organs. They have tiny slit-like tarsal sensory organs near the tips of their legs which help detect vibrations in the sand or soil. These organs can help provide information regarding the direction and distance from potential prey. Scorpions may also use substrate vibrations to identify potential mates and reduce violent interactions.
Communication Channels: tactile
Other Communication Modes: vibrations
Perception Channels: tactile ; vibrations
Deathstalkers have not been evaluated by the IUCN, US Fish and Wildlife Service, or CITES.
Many species of scorpions are habitat specific and their ranges are restricted. Few species of scorpions receive formal protection, and many may disappear before being described. Scorpions are increasingly threatened by habitat destruction and collection for souvenirs and the pet trade. Scorpions could also be vulnerable because of small litter sizes, long generation times, and high mortality of sexually immature females.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Little information is available regarding the specifics of development of deathstalkers. However, most scorpions are viviparous. Young receive nourishment in the uterus either through the the embryo and uterine wall similiar to placentals or through active transport if extra-embryonic membranes are present. Young are relatively large when born. Most scorpions molt multiple times before becoming adults, though juveniles look like adults at all instars.
Development - Life Cycle: neotenic/paedomorphic
Because of their potent venom, deathstalkers are one of the most dangerous scorpions on Earth.
Negative Impacts: injures humans (bites or stings, venomous )
Chlorotoxin originally isolated from venom of deathstalkers is used in cancer research. Research is also being pursued regarding the possible use of other components of their venom in the treatment of diabetes, as channels on which the neurotoxins act have been linked to the regulation of insulin. However, such research is still in its early stages. Scorpions are also good bio-indicators, as they are K-selected equilibrium species that comprise a major group of predatory arthropods in arid ecosystems. Their disappearance often indicates haabitat degradation. Programs to conserve terrestrial invertebrates often target scorpions.
Positive Impacts: source of medicine or drug ; research and education
Deathstalkers consume a variety of invertebrates and other scorpions. Deathstalkers are also preyed upon by vertebrates, centipedes, and other scorpions.
Scorpions, including deathstalkers, generally consume small insects, spiders, centipedes, earthworms, and other scorpions. Scorpions detect and capture prey using their sense of touch and by utilizing vibrations. They hide under stones, bark, wood, or other objects no the ground where they search for prey or wait in ambush. Once they capture prey, scorpions use their larger pincers to crush and draw prey toward the mouth.
Animal Foods: insects; terrestrial non-insect arthropods; terrestrial worms
Primary Diet: carnivore (Insectivore )
Deathstalkers, Leiurus quinquestriatus, are native to the Oriental, Palearctic, and Palearctic regions. Members of the nominal subspeices L. quinquestriatus quinquestriatus are found in northeastern Africa as far west as Algeria and Niger, as far south as Sudan, and as far west as Somalia. Members of the subspeices L. quinquestriatus hebraeus are found throughout the Middle East as far north as Turkey, east to Iran, and south to Oman and Yemen.
Biogeographic Regions: palearctic (Native ); oriental (Native ); ethiopian (Native )
Deathstalkers are found in arid and hyper-arid regions of North Africa and the Middle East. They generally reside under rocks or in abandoned burrows of other animals. They also create their own burrows about 20 cm below rocks.
Habitat Regions: terrestrial
Terrestrial Biomes: desert or dune
The lifespan of deathstalkers is not readily available. However, the lifespan of scorpions is variable, ranging from 4 to 25 years.
Deathstalkers are large venomous scorpions measuring 80 to 110 mm in length and weigh 1.0 to 2.5 g. They are yellowish in color with brown spots on the metasomal segment V and sometimes on the carapace and tergites. Tergites I and II have 5 carinae. The ventrolateral carinae have 3 to 4 rounded lobes, and the anal arch has 3 rounded lobes. Scorpions have 2 eyes on the top of the head and often 2 to 5 pairs of eyes on the front corners of their head.
Range mass: 1 to 2.5 g.
Range length: 80 to 110 mm.
Other Physical Features: venomous
Deathstalkers are commonly preyed upon members of their own speices and by other scorpions. Other invertebrate predators (e.g. centipedes) and vertebrates also prey on deathstalkers. They have high mortality directly after birth. Mortality is higher in adults than individuals of intermediate age.
Known Predators:
Courtship and sperm transfer in scorpions, including deathstalkers, is a complicated process involving a "romenade à deux." The male approaches a female and grasps her pedipalp chelae with his own chelae fingers. A form of dance then takes place, lasting for several minutes until the male ejects a spermatophore on suitable substrate. In the next stage, the male leads the female to position her genital aperture over the spermatophore, and the female takes up the sperm. Once sperm transfer has been completed, males and females usually separate.
Little is known about the specific reproductive behavior of deathstalkers. After a gestation period of 122 to 277 days (average 185), females give birth to 35 to 87 offspring (average 62.7).
Range number of offspring: 35 to 87.
Average number of offspring: 62.7.
Range gestation period: 155 to 227 minutes.
Average gestation period: 185 minutes.
Key Reproductive Features: sexual ; fertilization (External ); viviparous
Specific parental behaviors of deathstalkers have not been studied. However, in close relatives, young scorpions climb onto their mother’s back directly after birth. They remain on their mother's back for the duration of their first instar, taking advantage of their mother's protection. This also helps young regulate moisture.
Parental Investment: female parental care
Chemical Structure
Chlorotoxin is the key toxin found in the venom of Leiurus quinquestriatus. The 36-amino acid long peptide weighing 3,996 Da contains four disulfide bridges, as well as a single tyrosine residue. The presence of the four disulfide bridges, made from eight cysteine residues, gives chlorotoxin its highly folded and condensed structure, allowing the peptide to be delivered via the narrow extracellular matrix (Lippens et al., 1995). The tyrosine residue allows for radio-labelling using iodine isotopes (Mamelak et al., 2007).
Mode of Action
Chlorotoxin is the first ligand reported to inhibit the chloride ion channel. The binding was found to follow first-order binding kinetics, with a single chlorotoxin molecule being sufficient to block one chloride ion channel with high affinity (DeBin et al., 1991).
Chlorotoxin was also found to bind selectively to matrix metalloproteinase-2 (MMP-2), the expression of which is particularly elevated in tumour cells, including those of gliomas, primary prostate carcinoma, and rhabdomyosarcoma (Veiseh et al., 2007). Upon binding to the enzyme, the chlorotoxin-MMP-2 complex is endocytosed into the tumour cell, leading to the inhibition of enzymatic activity and reduction in the surface expression of MMP-2 (Deshane, et al., 2002). Additionally, metastasis is disrupted due to the reduction in MMP-2 expression, as MMP-2 is required to break through the extracellular matrix during tumour cell invasion (University of Washington, Apr. 2009).
Furthermore, by combining chlorotoxin with nanoparticles, it was found that anti-cancer therapy could be improved. While the attachment of nanoparticles allowed chlorotoxin to remain active for longer in the body, increasing its probability of reaching the tumour cell, the combination also led to the formation of chlorotoxin clusters around each nanoparticle. As an average of ten chlorotoxin molecules can congregate in one such cluster, numerous MMP-2 proteins can be inactivated simultaneously (University of Washington, Apr. 2009).
Potential Therapeutic Use
Due to chlorotoxin’s unique ability to target tumour cells while showing no binding to healthy cells, it is currently being studied as a potential treatment and means to identify gliomas, the most widespread of brain tumours. One such study, conducted by researchers at TransMolecular, Inc. (Cambridge, Massachusetts), successfully attached the radioactive iodine-131 isotope to synthetic chlorotoxin, TM-601. When the radio-labelled peptide was injected into the bloodstream, it was found to bind directly to tumour cells. Once bonded, the radiation destroyed the tumour cell without harming any surrounding healthy cells (Wu et al., 2010). The tumour-targeting drug received FDA approval in 2002 and was granted Orphan Drug Designation in 2008.
A novel method of detecting tumours with chlorotoxin is Tumour Paint, a CTX:Cy5.5 biconjugate consisting of chlorotoxin attached to the fluorescent dye, Cy5.5. The process of accurately identifying tumours is often an arduous one, relying on subtle visual cues, such as colour and texture (Veiseh, et al., 2007). By attaching the fluorescent dye to chlorotoxin, tumours can be illuminated, thus facilitating their localisation in clinical practice. The new visualisation technique was not only found to increase the contrast between tumour tissue and healthy tissue, but also found to improve the resolution significantly, thus that smaller tumours could be detected in earlier treatments (University of Washington, Aug. 2009).
The deathstalker (Leiurus quinquestriatus) is a species of scorpion, a member of the family Buthidae. It is also known as the Palestine yellow scorpion,[1][2][3][4] Omdurman scorpion, Naqab desert scorpion and by many other colloquial names, which generally originate from the commercial captive trade of the animal. To eliminate confusion, especially important with potentially dangerous species, the scientific name is normally used to refer to them. The name Leiurus quinquestriatus roughly translates into English as "five-striped smooth-tail".[5] In 2014, the subspecies L. q. hebraeus was separated from it and elevated to its own species Leiurus hebraeus.[6] Other species of the genus Leiurus are also often referred to as "deathstalkers". Leiurus quinquestriatus is yellow, and 30–77 millimetres (1.2–3.0 in) long, with an average of 58 mm (2.3 in).[7]
Leiurus quinquestriatus can be found in desert and scrubland habitats ranging from North Africa through to the Middle East. Its range covers a wide sweep of territory in the Sahara, Arabian Desert, Thar Desert, and Central Asia, from Algeria and Mali in the west through to Egypt, Ethiopia, Asia Minor and the Arabian Peninsula, eastwards to Kazakhstan and western India in the northeast and southeast.
Neurotoxins in L. quinquestriatus venom include:
The deathstalker is one of the most dangerous species of scorpions.[8][9] Its venom is a powerful mixture of neurotoxins, with a low lethal dose.[10] While a sting from this scorpion is extraordinarily painful, it normally would not kill a healthy adult human. However, young children, the elderly, or infirm (such as those with a heart condition and those who are allergic) are at much greater risk. Any envenomation runs the risk of anaphylaxis, a potentially life-threatening allergic reaction to the venom. A study from Israel shows a high rate of pancreatitis following envenomation.[11] If a sting from Leiurus quinquestriatus does prove deadly, the cause of death is usually pulmonary edema.
Antivenom for the treatment of deathstalker envenomations is produced by pharmaceutical companies Twyford (German)[12] and Sanofi Pasteur (French),[13] and by the National Antivenom and Vaccine Production Center in Riyadh.[14] Envenomation by the deathstalker is considered a medical emergency even with antivenom treatment, as its venom is unusually resistant to treatment and typically requires large doses of antivenom.[15]
In the United States and other countries outside of the typical range of the deathstalker, there is the additional complicating factor that none of the existing antivenoms are approved by the Food and Drug Administration (or equivalent agencies) and are only available as investigational drugs (INDs). The US Armed Forces maintain an investigational drug application[16] for the AVPC-Riyadh antivenom in the event of envenomation of soldiers in the Gulf War theater of operations, and the Florida Antivenin Bank, managed by the Miami-Dade Fire Rescue Department, maintains Sanofi Pasteur's Scorpifav antivenom for the deathstalker.[17]
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A component of the deathstalker's venom, the peptide chlorotoxin, has shown potential for treating human brain tumors.[18] There has also been some evidence to show that other components of the venom may aid in the regulation of insulin and could be used to treat diabetes.
In 2015 clinical trials were beginning of the use of chlorotoxin with a fluorescent molecule attached as brain tumour "paint" (BLZ-100), to mark cancerous cells in real time during an operation. This is important in brain cancer surgery, where it is vital both to remove as many cancerous cells as possible, but not to remove healthy tissue necessary for brain functioning. In preclinical animal trials the technique could highlight extremely small clusters of as few as 200 cancer cells, compared to the standard use of MRI, with a lower limit in excess of 500,000.[19]
Possession of L.quinquestriatus may be illegal or regulated in countries with laws prohibiting the keeping of dangerous animals in general. Jurisdictions are increasingly and explicitly including L.quinquestriatus in laws requiring permits to keep animals which are not usual pets, or restricting possession of dangerous animals, and in some cases have prohibited the keeping of L.quinquestriatus save by licensed zoos and educational facilities.
In several jurisdictions departments of fish and wildlife require permits for many animals,[20][21] and a number of cities and municipal governments have prohibited their possession in their bylaws.[22][23][24][25][26]
The deathstalker (Leiurus quinquestriatus) is a species of scorpion, a member of the family Buthidae. It is also known as the Palestine yellow scorpion, Omdurman scorpion, Naqab desert scorpion and by many other colloquial names, which generally originate from the commercial captive trade of the animal. To eliminate confusion, especially important with potentially dangerous species, the scientific name is normally used to refer to them. The name Leiurus quinquestriatus roughly translates into English as "five-striped smooth-tail". In 2014, the subspecies L. q. hebraeus was separated from it and elevated to its own species Leiurus hebraeus. Other species of the genus Leiurus are also often referred to as "deathstalkers". Leiurus quinquestriatus is yellow, and 30–77 millimetres (1.2–3.0 in) long, with an average of 58 mm (2.3 in).
