Diplopoda

de Blainville in Gervais, 1844

millipedes

() are a of myriapod characterized by having two pairs of jointed legs on most body , a result of segmental fusion during their evolutionary history over 400 million years ago. They are primarily that play critical roles in through decomposition of matter. The class contains approximately 12,000 described across 16 extant orders, with body forms ranging from elongated cylindrical forms to short, pill-like species capable of conglobation (rolling into a defensive ball).

Nemasomatidae by (c) Joeb, some rights reserved (CC BY), uploaded by Joeb. Used under a CC-BY license.

Gosodesmus claremontus by (c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda. Used under a CC-BY license.

Brachycybe lecontii by (c) Matt Muir, some rights reserved (CC BY), uploaded by Matt Muir. Used under a CC-BY license.

Pronunciation

How to pronounce Diplopoda: //ˈdɪpləˌpoʊdə//

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Images

Habitat

inhabit diverse terrestrial environments including forest floors, leaf litter, decaying wood, and soil. They require moist conditions and are particularly abundant in tropical rainforests where high humidity and abundant detritus support dense . Some are specialized for life under bark, within rotting logs, or in sandy soils.

Distribution

Global distribution with highest diversity in tropical regions. The is represented on all continents except Antarctica. Notable regional faunas include: Borneo with diverse rainforest including giant pill (Sphaerotheriida) and "noodle" millipedes (Pseudodesmus); California with the extremely localized relict Illacme plenipes; Chile with 75 described species showing high ; and Myanmar (Burma) where Cretaceous amber preserves 450+ specimens representing 13 of 16 modern orders.

Diet

Detritivorous, feeding primarily on decaying plant matter including fallen leaves, rotting wood, and other debris. Some consume mosses and . A minority of species, particularly in the order Colobognatha, have evolved elongated with for liquid feeding on plant or fungal tissues.

Life Cycle

Development occurs through : juveniles hatch with fewer and legs than , adding segments and leg pairs through successive until reaching sexual maturity. First may have as few as six legs. Adults continue molting throughout their multi-year lifespan. involves transfer, with some exhibiting prior to copulation.

Behavior

Most are slow-moving and secretive, seeking in soil or under cover objects during daylight hours. Many exhibit defensive behaviors including conglobation (rolling into a ball) in pill , or secretion of noxious or toxic compounds from defensive glands along the body margins when disturbed. Some species are gregarious, forming .

Ecological Role

engineers and key decomposers in terrestrial . fragment and consume dead plant material, accelerating and soil formation. Their feeding activities enhance soil structure and aeration. They serve as for diverse including , , birds, and small mammals. can reach 56 individuals per square meter in favorable .

Human Relevance

Generally harmless to humans; non-venomous and slow-moving. Some large tropical can secrete defensive compounds that may cause skin irritation. Occasionally considered minor garden pests when feeding on seedlings or soft plant tissues. Popular in educational settings and museum "petting zoos" for demonstrating anatomy and . Subject of scientific research due to their ancient lineage and conservation significance.

Similar Taxa

Chilopoda (centipedes)Both are myriapods with elongated bodies and numerous legs, but have one pair of legs per body (vs. two pairs in ), are venomous and predatory (vs. detritivorous), and are generally faster-moving with more prominent .
SymphylaSmall, pale myriapods with 12 pairs of legs and lacking the segmental fusion characteristic of ; found in similar soil but distinguished by having only one pair of legs per and no defensive secretions.