Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. The eight-legged arthropod is easily recognised due to its pair of grasping claws and the narrow, segmented tail, carried in a characteristic forward curve over the back, ending with a venomous sting. Though the scorpion has a fearsome reputation as a venomous pest, only 25 species worldwide have venom capable enough to kill a human being. Scorpions are an important motif in human culture and folklore. While a variety of physiological, morphological, biochemical and ecological adaptations have allowed the scorpions to flourish on earth from the Silurian period (443 - 416 mya) onwards, the basic shape of the scorpion has not changed much.