Pauropoda is a class of small, pale, millipede-like arthropods in the subphylum Myriapoda. More than 900 species in twelve families are found worldwide, living in soil and leaf mold. Pauropods look like centipedes or millipedes and may be a sister group of the latter, but a close relationship with Symphyla has also been posited.
Anatomy
thumb|Ventral and dorsal views of [[Pauropus amicus from New South Wales, Australia.]]
Pauropods are soft, cylindrical animals with bodies measuring only 0.3 to 2 mm in length. Pauropods can be identified because of their distinctive anal plate, which is unique to pauropods. Different species of pauropods can be identified based on the size and shape of their anal plate. The antennae are branching, biramous, and segmented, which is distinctive for the group. Pauropods are usually either white or brown. He wrote of the creature:<blockquote>Pauropus huxleyi is a bustling, active, neat and cleanly creature. It has, too, a look of cheerful intelligence, which forms a great contrast to the dull stupidity of the diplopods, or the melancholy ferocity of most chilopods.
Evolution and systematics
Only one fossil species has been reported: Eopauropus balticus a prehistoric species of pauropod that was found in Baltic Amber. The family Pauropodidae is especially large, with 27 genera and 814 species, including most of the genera and species in the class Pauropoda. Most species have nine pairs of legs as adults, but adults in four genera (Cauvetauropus, Aletopauropus, Zygopauropus, and Amphipauropus) have only eight pairs of legs, and adult females in the genus Decapauropus have either nine or ten pairs of legs. The order Tetramerocerata has a subcosmopolitan distribution. Male pauropods place small packets of sperm on the ground, which the females use to impregnate themselves. Parthogenesis can occur in some species, especially when environmental conditions are unfavourable.
The embryo goes through a short pupoid stage before the egg hatches and the first larval instar emerges. Juveniles then develop into adults through a series of molts, adding legs at each stage. Juveniles in the order Tetramerocerata start with three pairs of legs and progress through instars with five, then six, and then eight leg pairs, and in most species, become adults with nine leg pairs. In contrast, the first instar in the order Hexamerocerata has six leg pairs of legs and becomes an adult with eleven leg pairs. In at least some species in each order, adults continue to molt but no longer add legs or segments.
Behavior and diet
Paurapods have a distinctive method of movement characterized by bursts of speed and frequent changes of direction. Pauropods live in the soil, usually at densities of less than 100 per square metre (9/sq ft), and under debris and leaf litter.