spiders scorpions are arachnids
Like the insects and spiders, scorpions belong to the phylum Arthropoda and like the spiders they belong to the class Arachnida but belong to a different order, Scorpiones. See arachnid classification table. Scorpions are a diverse group of arachnids and include 16 families, 159 genera with 1260 described species worldwide.
Scorpions are ancient animals and fossil records indicate that they were already in existence about 425 – 450 million years ago during the Silurian period and evolved from an amphibious ancestor. They occur in habitats ranging from forest to deserts but it is in the arid areas that they are most common and diverse.