It used to be thought that all animals with six legs were insects. It is now widely accepted that there are two groups of six-legged animals – the insects (class Insecta) and the entognathous hexapods (class Entognatha).
Entognathous means “inside jaw” – which refers to how their mouthparts are enclosed in folds of the head. Hexapod means “6 legs”.
The star of the show is Heterojapyx, a dipluran in the order Diplura. Don’t know what that is? Please watch the video to find out. It’s an amazing animal!
There is an old blog post on the same subject here.