An order of ancestrally wingless Hexapoda comprising about 800 species and variously considered as apterygotan insects or as their independent sister group. These insects are equipped with three pairs of thoracic legs and a pair of antennae on the head. They are slender and white, but unlike typical insects they have intrinsic muscles in the antennal segments beyond the basal one. All diplurans lack eyes, and have paired mandibles and maxillae largely enclosed by fused folds of the head so that only the tips are exposed for retrieving food. The integument is thin and unpigmented, and the posterior end of the abdomen is furnished with a pair of cerci, which may be multisegmented (for example, in the family Campodeidae) or single segmented and modified into a pair of stout, pigmented jaws or forceps (in the family Japygidae and allied families) resembling those of adult earwigs and used for catching prey or for defense. The dipluran body size is usually small, under 0.4 in. (1 cm) long, but some Australian Heterojapyx species reach 2 in. (5 cm).