Scorpiones

Scorpions are a group of arachnids widely distributed on all continents and bioregions of the planet, except Antarctica, although most species are found in tropical and subtropical regions. 

They are solitary and nocturnal predators, using the strong pedipalpal chela, and the powerful toxins of their venom to immobilize their prey; all produce poison, which they use in capturing prey and as defense. 

The scorpions are arthropods, whose body size varies between 8.5 mm and 23 cm, their coloration is usually yellow, brown or black; some cave and humic species are depigmented and adapted to the microhabitats they occupy, which are distinguished by the metasoma, which is one of the most important appendages of scorpions, because at the terminal end they present the telson, which contains the venom gland and inoculating stinger. 

The oldest fossils date from the Silurian about 440 million years ago, their appearance is basically the same and their morphology remarkably stable, however, some fossil species reached up to one meter in length.