Myriapoda is a subphylum of arthropods containing millipedes, centipedes, and others. The group contains over 13,000 species, all of which are terrestrial. Although their name suggests they have myriad (10,000) legs, myriapods range from having over 750 legs (the millipede Illacme plenipes) to having fewer than ten legs.
Millipedes are arthropods in the class Diplopoda characterised by having two pairs of jointed legs on most body segments. Each double-legged segment is a result of two single segments fused together as one. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a ball. Although the name "millipede" derives from the Latin for "thousand feet", no known species has 1,000; the record of 750 legs belongs to Illacme plenipes
They are elongated metameric creatures with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs, ranging from 30 to 354. Centipedes always have an odd number of pairs of legs. Therefore, there is no centipede with exactly 100 legs. A key trait uniting this group is a pair of venom claws or forcipules formed from a modified first appendage. Centipedes are a predominantly carnivorous taxon. Size can range from a few millimetres in the smaller lithobiomorphs and geophilomorphs to about 30 cm.