proturan

proturan, any of a group of about 800 species of minute (0.5 to 2 mm [0.02 to 0.08 inch]), pale, wingless, blind, primitive insects that live in damp humus and soil and feed on decaying organic matter. Proturans, also 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 most 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.

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The proturans traditionally have been classified as insects, usually placed in the class Protura or the order Protura (class Entognatha). Some authorities, however, consider the proturans distinct from true insects and place them in the subclass Parainsecta (class Entognatha), along with the springtails (order Collembola).