Archaeognatha

Archaeognatha is an order of wingless insects, also known as "jumping bristletails". They are among those insects which changed least during evolution. They first appear in the Devonian period along with the arachnids (Spiders). The name Archaeognatha is derived from Greek "Archaeos" meaning "ancient" and "gnatha" meaning "jaw". This refers to the articulation of the mandibles, which has a single condyle, where all higher insects have two. An alternate name, "Microcoryphia" comes from the Greek "micro" meaning "small" and "coryphia" meaning head.
The Order Archaeognatha has previously been combined with the Order Thysanura, or bristletails. Both groups have three-pronged tails with two cerci and an epiproct. Archaeognatha differ from Thysanura in that they are able to use their tail to spring up to 30 cm into the air. Like Thysanura, the body is covered with scales, with a thin exoskeleton that is susceptible to dehydration.
There are approximately 350 species in the two families. They are distributed worldwide, and unusual in the insect world in that they can even be found in the Arctic where they live in leaf litter and rock crevices. They feed primarily on algae, but also lichens, mosses, or decaying organic materials.
There are no species at current conservation risk, though the order is one of the most poorly-studied among insects, and therefore it may simply be that no one has yet recognized that any species are at risk.