Millipedes form the class Diplopoda. Most millipedes are slower than centipedes, and feed on leaf litter and detritus. Except for the first segment called collum, which don't have any appendages, and the next three segments with a single pair of legs each, they are distinguished by the fusion of each pair of body segments into a single unit, giving the appearance of having two pairs of legs per segment. It is also common for the sternites, pleurites and tergites to fuse into rigid armour rings.A review of the correlation of tergites, sternites, and leg pairs in diplopods The males produce aflagellate sperm cells, unlike the rest of the myriapods which produce flagellated sperm.Invertebrate Zoology: A Tree of Life Approach Around 12,000 species have been described, which may represent less than a tenth of the true global millipede diversity. Although the name "millipede" is a compound word formed from the Latin roots millia ("thousand") and pes (gen. pedis) ("foot"), millipedes typically have between 36 and 400 legs. In 2021, however, was described Eumillipes persephone, the first species known to have 1,000 or more legs, possessing 1,306 of them. Pill millipedes are much shorter, and are capable of rolling up into a ball, like pillbugs.
