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For an article concerning taxonomic classification, see Scorpiones. For the category, see Category:Scorpiones

Pandinus imperator

Pandinus imperator

Scorpions are arachnids characterised by the presence of two pincers and a venomous stinger at the end of their “tails”. Nine families and 1400 species of scorpions exist in the world today. Their stings contain venom that will cause pain where you are stung, but the smaller the scorpion, the more venom it has. A scorpion's feeding habits consist only of insects. The order of scorpions is Scorpiones.

Biology[]

Morphology[]

scorpions are mainly characterised by their modified frontal pair of pedipalps resembling a crabs pincers as well as the long metasoma (tails) at their rear with a venomous bulb (telson) at the end on the tail linked to a stinger (aculeus)They have 8 pairs of appendages, and a cephalothorax (fused head & body). Their abdomens are usually long and elliptical. They vary colour and sizes ranging between 4-12 cm in terms of body length. The largest scorpion reaches 23 cm in length whereas the smallest is just 0.5 inches long. They are usually brown, beige, black, grey, orange and red in colour. A notable feature is the fact that they carry a fluorescent substance in their exoskeleton which glows under UV light[1], a scorpion’s body is divided into three parts, Prosoma (Cephalothorax), Mesosoma (sub-abdomen) and Metasoma (Tail), The cephalothorax bears multiple pairs of small eyes. they have large Chelicerae are well developed and closely resemble that of solifugids, bearing sharp “teeth” Like structures. The Mesosoma is divided into eight segments or tagmata each being reinforced and armoured by a set of plates, the mesosoma contains most of the vital organs, the brain is located just behind the cephalothorax, as with other related arachnids. The cephalothorax bears several nerve endings.

Spacial perception and sensory organs[]

A scorpions eyes while unable to farm sharp and clear images, are one of the most highly light-sensitive in the animal kingdom, it is presumed that the starlight emitted by the stars as well as the moonlight aid in navigation. A scorpions body is covered with sensory bristles and proprioreceptors, The proprioreceptors are responsible for the sense of self-movement, force, and body position, Scorpions also have pectines which are comblike structures in an inverted V shape present on the ventral side of the mesosoma which help in sensing the environment, the modified pedipalps also function as Sensory organs.

Behaviour[]

Threat display & defence mechanism[]

Both sexes display a unique display upon being threatened which involves the raising and inclining their metasoma towards the predator, displaying their aculeus, and opening their pincers. A few insect species are known to mimic a scorpion threat display (such as Extatosoma tiaratum) the display not only presents the creature as being larger in terms of size to any predators but also make the Aculeus much more conspicuous to any predators. A scorpion uses its stinger both for killing prey and defense. Some species make direct, quick strikes with their tails while others make slower, more circular strikes which can more easily return the stinger to a position where it can strike again. Leiurus quinquestriatus can whip its tail at a speed of up to 128 cm/s (50 in/s) in a defensive strike, some species have also been observed squirting any predators with poison as a deterrent in a fashion similar to that of a spitting cobra.

Mating[]

species in some genera, such as Hottentottaand Tityus, and the species Centruroides gracilis, Liocheles australasiae, and Ananteris coineaui have been reported, not necessarily reliably, to reproduce through parthenogenesis, in which unfertilized eggs develop into living embryos. Receptive females produce pheromones which are picked up by wandering males using their pectines to comb the substrate. Males begin courtship by moving their bodies back and forth, without moving the legs, a behavior known as juddering. This appears to produce ground vibrations that are picked up by the female.

promenade à deux & Courtship behaviours[]

during couplation, the female and male grasp onto each other’s pincers and “dance” all the while the male attempts to reach the female’s sexual organs and find a suitable place to deposit the spermatozoa in order to reproduce this dance has been aptly named “promenade à deux” (French for “Walk of two”), this courtship ritual is common in most species, along with other behaviour’s occurring during mating. The courtship ritual can involve several other behaviors such as a cheliceral kiss, in which the male and female grasp each other's mouth-parts, arbre droit("upright tree") where the partners elevate their posteriors and rub their tails together, and sexual stinging, in which the male stings the female in the chelae or mesosoma to subdue her. The dance can last from a few minutes to several hours.

Feeding habits[]

scorpions are Predacious animals and usually feed on a variety of invertebrates. Some can also become cannibal in the absence of food sources. Large tropical species can consume vertebrates such as mice. The are known to feed on insects, spiders and smaller scorpion species. They either crush their prey with their pincers (this form of hunting is much more conspicuous in species with larger pincers) whereas Scorpions with more robust and potent toxins have evolved to use the properties of their lethal venom in order to subdue prey for consumption. The chelicerae of most scorpions greatly resembles that of Solifugids, being represented as a muscular mandible with two pincer-like ”teeth” at the end. Their modified claws, although not as powerful and large as some crustaceans, can still be effectively used for prey immobilisation allowing their chelicerae to tear apart their prey.

Life cycle & maternal care[]

The female gives birth to live young and she exhibits maternal care by carrying them on her back till they molt and reach adolescence[2]. The young ones are pale and coloureless. They are hemimatobolous with no pupal stage and undergo a gradual transition from juvenile to adults, as with other arthropods, scorpions will eventually outgrow their exoskeletons through a procedure known as ecdysis, ecdysis usually occurs multiple times throughout their lives this is due to the fact that their exoskeletons do not grow with them, hence they eventually outgrow their carapace which needs to be renewed, after ecdysis the juvenile scorpions are highly susceptible to damage as their new exoskeletons need ample time to harden. Gestation in scorpions can last for over a year in some species. They have two types of embryonic development; apoikogenic and katoikogenic. In the apoikogenic system, which is mainly found in the Buthidae, embryos develop in yolk-rich eggs inside follicles. The katoikogenic system is documented in Hemiscorpiidae, Scorpionidae and Diplocentridae, and involves the embryos developing in a diverticulum which has a teat-like structure for them to feed though.Unlike the majority of arachnids, which are oviparous, hatching from eggs, scorpions seem to be universally viviparous, with live births. They are unusual among terrestrial arthropods in the amount of care a female gives to her offspring. The size of a brood varies by species, from 3 to over 100. The body size of scorpions is not correlated either with brood size or with life cycle length.

Toxicity[]

scorpions are usually not very dangerous to humans, only 25 species can seriously harm a human (less than 1% of all species[3]) the most fatal sting is delivered by the Deathstalker (it really lives up to the name). The larger the pincers, the lower the toxicity the ones that are large are usually not very dangerous, this is such because species with larger pincers are reliant on their sheer strength to overcome their prey while the ones with larger and more robust stings tend to have a greater toxicity as they are generally more reliant on the properties of their venom rather than their strength.

Predation[]

Inspite of their ferocious reputation in the ecosystem, several predators will accept scorpions as a food source whenever the opportunity arises, The grasshopper mouse survives in the deserts of southwest United States by feeding on the bark scorpion, which are plentiful, due to other resources being less common, The scorpion uses its stinger to inject toxins into the nervous and muscle tissues which causes disruption in the animal's sensory system. However, as the scorpions stinger evolves to become more toxic, the mice evolve in order to cope with the toxins. Therefore, the grasshopper mice have sensory neurons that have evolved which reject the toxins and prevents pain signals, another predator known to feed on scorpions is the Western Banded Gecko, The lizards use very fast and precise movements, shaking their heads from side to side, in order to immobilize scorpions caught in their mouths. Researchers believe that this may be done in order to prevent the scorpions from injecting them with their venom. Other predators include Birds (mostly owls), lizards, a few small snakes, mammals (some rodents and carnivores), and frogs and toads all eat scorpions mainly due to their abundance as well as their size which makes them a very valuable source of food.

Geolocation[]

Range[]

Scorpions can be found throughout the world on all continents except Antarctica and a few other areas in the frigid regions. Their density is generally concentrated in tropical and arid climates, yet are commonly associated with deserts in traditional cultures.

Habitats[]

Scorpions are most commonly found in dry or humid areas notably ones with high temperatures. Their preferred habitats include desert regions, scrub lands, tropical rainforests etc. Scorpions prefer areas where the temperature remains in the range of 11–40 °C (52–104 °F), but may survive temperatures from well below freezing to desert heat.Scorpions can withstand intense heat: Leiurus quinquestriatus, Scorpio maurus and Hadrurus arizonensis can live in temperatures of 45–50 °C (113–122 °F) if they are sufficiently hydrated.

See Also[]

References[]

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