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Title: Millipedes  
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Subject: Synopses of the British Fauna
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For other uses, see Millipede (disambiguation).
Temporal range: 428–0Ma
Late Silurian to Recent
Rusty millipede (Trigoniulus corallinus)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Myriapoda
Class: Diplopoda
De Blainville in Gervais, 1844 
Subclasses and orders 
See text

Millipedes are myriapods that have two pairs of 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 bodies, although some are flattened dorso-ventrally, while pill millipedes are shorter and can roll into a ball, like a pillbug.

The name "millipede" is a compound word formed from the Latin roots mille ("thousand") and pes ("foot"). Despite their name, no known millipede has 1,000 legs, although the rare species Illacme plenipes has up to 750.[1] Common species have between 36 and 400 legs. The class contains over 12,000 named species in 16 orders and 147 families.[2] The giant African millipede (Archispirostreptus gigas), is the largest species of millipede.

Millipedes are detritivores and often slow moving. Most millipedes eat decaying leaves and other dead plant matter, moisturising the food with secretions and then scraping it in with their jaws. However, they can also be minor garden pests, especially in greenhouses where they can cause severe damage to emergent seedlings. Signs of millipede damage include the stripping of the outer layers of a young plant stem and irregular damage to leaves and plant apices, the very top of a plant.

Millipedes can be easily distinguished from the somewhat similar and related centipedes (Class Chilopoda) which move rapidly, are carnivorous, and have a single pair of legs for each body segment.


This class of arthropod is thought to be among the first animals to have colonised land during the


File:Red millipede crawling on a wall.webm Millipedes range from 2 to 280 millimetres (0.079 to 11.024 in) in length, and can have as few as eleven, to over a hundred segments. They are generally black or brown in colour, although there are a few brightly coloured species.

The millipede's most obvious feature is its large number of legs. Having many short legs makes millipedes rather slow, but they are powerful burrowers. With their legs and body length moving in a wavelike pattern, they easily force their way underground head first. They also seem to have some engineering ability, reinforcing the tunnel by rearranging the particles around it. Their bodies have segmented sections which makes them move in a wave-like form.

The head of a millipede is typically rounded above and flattened below and bears large mandibles. The body is flattened or cylindrical, with a single chitinous plate above, one at each side, and two or three on the underside. In many millipedes, these plates are fused to varying degrees, sometimes forming a single cylindrical ring. The plates are typically hard, being impregnated with calcium salts.[5] Because they lack a waxy cuticle, millipedes are susceptible to water loss and must spend most of their time in moist or humid environments.[6]

The first segment behind the head is legless and known as a collum. The second to fourth body rings bear a single pair of legs each. The remaining segments, from the fifth to the posterior, are properly known as diplosegments, or double segments. Each diplosegment bears two pairs of legs, rather than just one as in centipedes. This is because each diplosgment is formed by the fusion of two embryonic segments. In some millipedes the last few segments may be legless. The terms "segment", "diplosegment", and "body ring" are often used interchangeably. The final segment bears a telson, which consists of a pre-anal ring, pair of anal valves, and subanal scale.[5][7]

Millipedes breathe through two pairs of spiracles on each diplosegment. Each opens into an internal pouch, and connects to a system of tracheae. The heart runs the entire length of the body, with an aorta stretching into the head. The excretory organs are two pairs of malpighian tubules, located near the mid-part of the gut.[5]

The head contains a single pair of antennae, and in many orders a pair of sensory organs known as the Tömösváry organs. These are found just posterior and lateral to the antennae, and are shaped as small and oval rings at the base of the antennae. They are probably used to measure the humidity in the surroundings, and they may have some chemoreceptory abilities too. Millipede eyes consist of a number of simple flat-lensed ocelli arranged in a group on the front or side of the head. Many species of millipedes, including cave-dwelling millipedes such as Causeyella, and the entire order Polydesmida have secondarily lost their eyes.

According to Guinness World Records the African giant black millipede Archispirostreptus gigas can grow to 38.6 centimetres (15.2 in).[8]


Most millipedes are herbivorous, and feed on decomposing vegetation or organic matter mixed with soil. A few species are omnivorous or carnivorous, and may prey on small arthropods, such as insects and centipedes, or on earthworms. Some species have piercing mouth parts that allow them to feed on plant juices.[9]

The digestive tract is a simple tube with two pairs of salivary glands to help digest the food. Many millipedes moisten their food with saliva before eating it.[5]


Millipedes show a diversity of mating styles and structures. In the basal order Polyxenida, males deposit spermatophores that are subsequently picked up by females.[9] In all other millipede groups, males possess one or two pairs of modified legs called gonopods which are used to transfer sperm to the female during copulation. The location of the gonopods differs between groups: in males of the Pentazoniia they are located at the rear of the body and known as telopods, while in Helminthomorpha- the vast majority of species- they are located on the 7th body segment.[7] A few species are parthenogenetic, having few, if any, males.[10][11]

The genital openings are located on the third segment, and are accompanied in the male by one or two penises, which deposit the sperm packets onto the gonopods. In the female, the genital pores open into a small chamber, or vulva, which is covered by a small hood-like cover, and is used to store the sperm after copulation.[5]

Females lay between ten and three hundred eggs at a time, depending on species, fertilising them with the stored sperm as they do so. Many species simply deposit the eggs on moist soil or organic detritus, but some construct nests lined with dried faeces.

The young hatch after a few weeks, and typically have only three pairs of legs, followed by up to four legless segments. As they grow, they continually moult, adding further segments and legs as they do so. Some species moult within specially prepared chambers, which they may also use to wait out dry weather, and most species eat the shed exoskeleton after moulting. Millipedes live from one to ten years, depending on species.[5]

Defence mechanisms

Due to their lack of speed and their inability to bite or sting, millipedes' primary defence mechanism is to curl into a tight coil – protecting their delicate legs inside an armoured body exterior. Many species also emit poisonous liquid secretions or hydrogen cyanide gas through microscopic ozopores (also called odoriferous or repugantorial glands), along the sides of their bodies as a secondary defence.[12][13][14] Some of these substances are caustic and can burn the exoskeleton of ants and other insect predators, and the skin and eyes of larger predators. Animals such as wedge-capped capuchins have been observed intentionally irritating millipedes in order to rub the chemicals on themselves to repel mosquitoes.[15][16] Some of these defensive compounds also show antifungal activity.[17] At least one species, Polyxenus fasciculatus, employs detachable bristles to entangle ants.[18]

As far as humans are concerned, this chemical brew is fairly harmless, usually causing only minor effects on the skin, the main effect being discoloration, but other effects may also include pain, itching, local erythema, edema, blisters, eczema, and occasionally cracked skin.[13][19][20][21] Eye exposures to these secretions causes general eye irritation and potentially more severe effects such as conjunctivitis and keratitis.[22] First aid consists of flushing the area thoroughly with water; further treatment is aimed at relieving the local effects.


The living members of the Diplopoda are divided into sixteen orders in two subclasses.[2] There are nine extinct orders. The basal subclass Penicillata contains small species whose exoskeleton is not calcified, and which are covered in setae or bristles. All other millipedes belong to the subclass Chilognatha.

The infraclass Pentazonia contains the short-bodied pill millipedes, which are capable of rolling themselves into a ball ("volvation"). The infraclass Helminthomorpha contains the great majority of millipede species.[23][24]

The higher-level classification of millipedes is presented below, based on Shear, 2011,[2] and Shear & Edgecombe, 2010[25] (extinct groups). Recent cladistic and molecular studies have challenged traditional classification schemes, and in particular the position of the orders Siphoniulida and Polyzoniida is not yet well established.[7] The placement and positions of extinct groups (†) known only from fossils is tentative and not fully resolved.[7][25]

Class Diplopoda de Blainville in Gervais, 1844

  • Subclass Penicillata Latrielle, 1831
    • Order Polyxenida Verhoeff, 1934
  • Subclass †Arthropleuridea (placed in Penicillata by some authors)[25]
  • Subclass Chilognatha Latrielle, 1802
    • Order †Zosterogrammida Wilson, 2005 (Chilognatha incertae sedis)[25]
    • Infraclass Pentazonia Brandt, 1833
      • Order †Amynilyspedida Hoffman, 1969
      • Superorder Limacomorpha Pocock, 1894
        • Order Glomeridesmida Cook, 1895
      • Superorder Oniscomorpha Pocock, 1887
    • Infraclass Helminthomorpha Pocock, 1887
      • Order †Pleurojulida Schneider & Werneburg, 1998 (possibly sister to Colobognatha)[7]
      • Superorder †Archipolypoda Scudder, 1882
        • Order †Archidesmida
        • Order †Cowiedesmida
        • Order †Euphoberiida
        • Order †Palaeosomatida
      • Subterclass Colobognatha Brandt, 1834
        • Order Platydesmida Cook, 1895
        • Order Polyzoniida Cook, 1895
        • Order Siphonocryptida Cook, 1895
        • Order Siphonophorida Newport, 1844
      • Subterclass Eugnatha Attems, 1898
        • Superorder Juliformia Attems, 1926
          • Order Julida Brandt, 1833
          • Order Spirobolida Cook, 1895
          • Order Spirostreptida Brandt, 1833
          • Superfamily †Xyloiuloidea Cook, 1895 (Sometimes aligned with Spirobolida)[26]
        • Superorder Nematophora Verhoeff, 1913
          • Order Callipodida Pocock, 1894
          • Order Chordeumatida Pocock 1894
          • Order Stemmiulida Cook, 1895
          • Order Siphoniulida Cook, 1895
        • Superorder Merochaeta Cook, 1895

See also

Arthropods portal


External links

  • Myriapods: The World's Leggiest Animals
  • Millipedes of Australia
  • Milli-PEET: The Class Diplopda-The Field Museum, Chicago IL
  • World Checklist of Millipede Groups
  • Diplopoda Taxonomy Site
  • Video of a millipede from Thailand

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