Protura

Proturans have no compound eyes, wings, or antennae, and, lacking pigmentation, are usually whitish or pale brown. The sensory function of the absent antennae is fulfilled by the first pair of the three pairs of five-segmented legs, which are held up, pointing forward, and bearing numerous tarsal sensilla and sensory hairs. They ambulate using the four rear legs. The head is conical, and bears two pseudoculi with unknown function. The body is elongated and cylindrical, with a post-anal telson at the end. The mouthparts are entognathous (enclosed within the head capsule) and consist of narrow mandibles and maxillae. The first three abdominal segments bear short limb-like appendages, Only the two families Eosentomidae and Sinentomidae possess a simple tracheal system with a pair of spiracles on both the mesothorax and the metathorax, while proturans in the remaining families lack these structures and perform gas exchange by diffusion. == Ecology ==

Proturans live chiefly in soil, mosses, and leaf litter They have also been found beneath rocks or under the bark of trees, Although they are sometimes regarded as uncommon, The diet of proturans has not yet been sufficiently observed to be characterised. In laboratory culture, they may be fed mycorrhizal fungi, dead mites and pulverized, dried mushrooms; == Development ==

The nymph has 8 abdominal segments plus the telson; the number of abdominal segments increases through moulting until the full adult complement of 12 abdominal segments is achieved. Further moults may occur, but do not add additional body segments; it is still not known whether the adults continue to moult throughout their lives. Eggs have been observed in only a few species. In most proturan families, five developmental stages follow the egg stage: the prenymph hatches from the egg and has only weakly developed mouthparts and 8 abdominal segments; nymph I follows and has fully developed mouthparts; nymph II has 9 abdominal segments; "maturus junior" has 11 abdominal segments, and moults into the sexually mature adult. Male individuals of the family Acerentomidae differ from this five-stage scheme, having an additional developmental stage, the preimago, which has partially developed genitalia and appears between the "maturus junior" and the adult stage. == History ==

Proturans were first discovered in the early 20th century, when Filippo Silvestri and Antonio Berlese independently described the animals. The first species to be described was Acerentomon doderoi, published in 1907 by Silvestri, based on material found near Syracuse, New York. == References ==