Symphyla(redirected from Symphylan)
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a class of small arthropods of the group Myrio-poda. The body, which measures about 8 mm long, is white or yellowish. The head bears a pair of moniliform antennae and three pairs of mouthparts; eyes are absent. The body has 12 pairs of legs, and at the base of the third to 12th pairs there are bulging membranous sacs through whose walls water is absorbed. The respiratory system, which consists of tracheae, starts with a single pair of spiracles in the head.
The mode of fertilization is unique. The male deposits sper-matophores on the walls of passages in the soil. The female picks up the spermatophores with her mouthparts; in doing so the sperm penetrate cavities in the female’s jaws. The female then, with her jaws, grasps an egg emerging from an opening on the third body segment; the egg is fertilized by the sperm at this time. The fertilized egg is finally attached to the substrate. Upon hatching, the larvae have an incomplete number of body segments, either six or seven.
Symphyla develop and live in soil, in the forest litter, or under stones; they feed on decaying plant remains. The arthropods sometimes injure the delicate rootlets of seedlings in greenhouses. There are about 120 species, distributed on all continents except Antarctica. The Symphyla fauna of the USSR has not been adequately studied. The name of one of the families of Symphyla, Scolopendrellidae, was formerly applied to the entire class.