Myriapod

Myriapoda is a subphylum of arthropods that includes millipedes, centipedes, pauropods, and symphylans. The name derives from the Greek for "countless feet," reflecting their elongated, multi-segmented bodies and numerous legs. All myriapods are generally terrestrial and occupy moist habitats such as soil, leaf litter, and under logs or stones.

The four living groups differ in body plan and ecology. Centipedes (Chilopoda) have a single pair of legs per body segment and are typically fast, carnivorous predators equipped with venomous forcipules used to subdue prey. Millipedes (Diplopoda) possess two pairs of legs per diplosegment and are primarily detritivores or decomposers, feeding on decaying plant matter; they tend to be slow and may emit defensive chemicals when threatened. Pauropods (Pauropoda) and symphylans (Symphyla) are smaller, soil-dwelling groups with fewer legs and simpler body plans, often feeding on decaying organic material, fungivory, or microfauna in the litter layer.

Anatomically, myriapods have a head equipped with antennae and mouthparts, followed by a long trunk of repeating segments. They differ from other arthropods in their segmented organization and appendage arrangement, though they share a common arthropod skeleton and ventral nerve cord.

Reproduction is primarily sexual, with eggs laid by females and offspring undergoing direct development or simple metamorphosis. Myriapods are important in ecosystems as predators, scavengers, and contributors to soil formation and nutrient cycling. The fossil record of myriapods extends to the Silurian period, with modern lineages diversifying in later Paleozoic and post-Paleozoic times.