Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). The three orders are sometimes grouped together in a class called Entognatha because they've internal mouthparts, but they don't appear to be more closely related to one another than to insects, which have external mouthparts. Some DNA sequence studies suggest that Collembola are a separate evolutionary line from the other Hexapoda… (More on Springtail)