PROTURAN

(class or order Protura), member of a group of minute (0.5 to 2 mm [0.02 to 0.08 inch]), pale, wingless, blind, primitive insects (about 150 species) that live in damp humus and soil and feed on decaying organic matter. Proturans, frequently known as telsontails, include some of the most primitive hexapods (i.e., animals with six legs). They are worldwide in distribution, although the group was unknown before 1907. Unlike winged insects, proturans lack antennae and possess 12 abdominal segments (instead of the typical 11), 3 of which are added postembryonically in successive nymphal molts, or sheddings of skin (anamorphosis). The front legs, carried like antennae, serve a sensory function. The cone-shaped head has anterior sucking mouthparts. There is a pair of ventral styli on each of the first three abdominal segments. Some authorities consider the proturans distinct from true insects.