Centipedes (from Latin prefix centi-, "hundred", and
pes, pedis, "foot") are arthropods belonging to the class Chilopoda of
the subphylum Myriapoda. 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 (12 in) in the largest scolopendromorphs.
Centipedes can be found in a wide variety of environments. Centipedes normally
have a drab coloration combining shades of brown and red. Cavernicolous
(cave-dwelling) and subterranean species may lack pigmentation and many tropical
scolopendromorphs have bright aposematic colours.
Worldwide, there are estimated to be 8,000 species of centipede, of which 3,000 have
been described. Centipedes have a wide geographical
range where they even reach beyond the Arctic Circle. Centipedes
are found in an array of terrestrial habitats from tropical
rainforests to deserts. Within these
habitats, centipedes require a moist micro-habitat because they lack the waxy cuticle of insects and arachnids, and so lose water rapidly through the
skin. Accordingly, they
are found in soil and leaf litter, under stones and dead wood, and inside
logs. Centipedes are among the largest terrestrial invertebrate predators and often contribute significantly to the
invertebrate predatory biomass in terrestrial ecosystems.