Temporal range: 428–0Ma Late Silurian to Recent
|Rusty millipede (Trigoniulus corallinus)|
De Blainville in Gervais, 1844
|Subclasses and orders|
Millipedes are myriapods of the class Diplopoda 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 (the name "Diplopoda" comes from the Greek words διπλοῦς (diplous), "double" and ποδός (podos), "foot"). 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, 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. Common species have between 36 and 400 legs. There are approximately 12,000 named species in ca. 140 families. The longest species is the giant African millipede (Archispirostreptus gigas).
Most millipedes are slow-moving detritivores, eating decaying leaves and other dead plant matter. However, they can also be minor garden pests, especially in greenhouses where they can cause severe damage to emergent seedlings.
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. The scientific study of millipedes is known as diplopodology, and a scientist who studies them is called a diplopodologist.
This class of arthropod is thought to be among the first animals to have colonised land during the Silurian geologic period. These early forms probably ate mosses and primitive vascular plants. The oldest known land creature, Pneumodesmus newmani, was a 1 cm (0.39 in) long millipede, and lived 428 million years ago. In the Upper Carboniferous ( ), Arthropleura became the largest known land invertebrate of all time, reaching lengths of up to 2.6 m (8 ft 6 in). Millipedes, centipedes, and other terrestrial arthropods attained very large sizes in comparison to modern species in the oxygen-rich environments of the Devonian and Carboniferous periods, and some could grow larger than one metre. As oxygen levels lowered through time, arthropods became smaller in size.
Millipedes range from 2 to 280 mm (0.079 to 11.0 in) in length, and can have as few as eleven to over one 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 the many legs pushing in unison provides powerful strength for burrowing.
The head of a millipede is typically rounded above and flattened below and bears a pair of large mandibles in front of a plate-like structure called a gnathochilarium ("jaw lip").
The head contains a single pair of antennae with seven or eight segments and a group of sensory cones at the tip. Many orders also possess a pair of sensory organs known as the Tömösváry organs, shaped as small oval rings posterior and lateral to the base of the antennae. Their true function is unknown, but they also occur in some centipedes, and are possibly used to measure humidity or light levels in the surrounding environment.
Millipede eyes consist of a number of simple flat-lensed ocelli arranged in a group on the 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.
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. Because they lack a waxy cuticle, millipedes are susceptible to water loss and must spend most of their time in moist or humid environments.
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 and are known as "haplosegments" (from the Greek haplo: single). 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" and "body ring" are often used interchangeably. The final segment bears a telson, which consists of a legless preanal ring, pair of anal valves (closeable plates around the anus), and a subanal scale.
Millipedes in several orders have keel-like extensions of the body-wall known as paranota, which can vary widely in shape and size. They may allow millipedes to wedge more securely into crevices, protect the legs, or make the millipede more difficult for predators to swallow.
Millipedes breathe through two pairs of spiracles located ventrally on each segment. 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. The digestive tract is a simple tube with two pairs of salivary glands to help digest the food.
Reproduction and growth
Millipedes show a diversity of mating styles and structures. In the basal order Polyxenida, males deposit spermatophores that are subsequently picked up by females. 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 Pentazonia 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. A few species are parthenogenetic, having few, if any, males.
Gonopod morphology is the predominant means of determining species among millipedes: the complex structures differ much between species but very little within a species.
The genital openings are located on the third segment, and are accompanied in the male by one or two penes which deposit the sperm packets onto the gonopods. In the female, the genital pores open into paired small sacs called cyphopods or vulvae, which are covered by a small hood-like cover, and are used to store the sperm after copulation.
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, and may protect the eggs within silk cocoons. In most species the female abandon the eggs after laying but some species in the orders Platydesmida and Stemmiulida provide parental care for eggs and young.
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 of soil or silk, 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.
In temperate zones, millipedes are most abundant in moist deciduous forests, but they also occur in coniferous forests, deserts, caves, and alpine ecosystems. Some species can survive freshwater floods and live submerged underwater for up to 11 months. A few species occur near the seashore and can survive in somewhat salty conditions.
Most millipedes are detritivores and feed on decomposing vegetation or organic matter mixed with soil. Millipedes in the order Polyxenida graze algae from bark, and Platydesmida feed on fungi. A few species are omnivorous or occasionally carnivorous, feeding on insects, centipedes, earthworms, or snails Some species have piercing mouth parts that allow them to feed on plant juices.
Predators and parasites
Millipedes are preyed upon by a wide range of animals, including various reptiles, amphibians, birds, mammals, and insects. Mammalian predators such as coatis and meerkats roll captured millipedes on the ground to deplete defensive secretions and rub them off the body before consuming, while certain poison dart frogs are believed to incorporate the toxic compounds of millipedes into their own defenses. Several invertebrates have specialized behaviors or structures to feed on millipedes, including larval glowworm beetles, Probolomyrmex ants, chlamydephorid slugs, and the predaceous dung beetle Deltochilum valgum.
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 various poisonous liquid secretions through microscopic ozopores (also called odoriferous or repugantorial glands), along the sides of their bodies as a secondary defence. These secretions may include alkaloids, benzoquinones, phenols, terpenoids, and/or hydrogen cyanide, among many others. 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. Primates such as capuchin monkeys and lemurs have been observed intentionally irritating millipedes in order to rub the chemicals on themselves to repel mosquitoes. Some of these defensive compounds also show antifungal activity. The bristly millipedes (order Polyxenida) lack both an armoured exoskeleton and odiferous glands, and instead are covered in numerous bristles that in at least one species, Polyxenus fasciculatus, detach and entangle ants.
Millipedes in relation to people
Millipedes do not bite, and their defensive secretions of are mostly harmless to humans- usually causing only minor discoloration on the skin- but the secretions of some tropical species may cause pain, itching, local erythema, edema, blisters, eczema, and occasionally cracked skin. Eye exposures to these secretions causes general eye irritation and potentially more severe effects such as conjunctivitis and keratitis. First aid consists of flushing the area thoroughly with water; further treatment is aimed at relieving the local effects.
Some millipedes are considered household pests, including Xenobolus carnifex which infests thatched roofs in India. Other species exhibit periodical swarming behaviour, which can result in home invasions, crop damage, train delays, or even train crashes and derailments.
Some of the larger millipedes in the orders Spirobolida, Spirostreptida, Sphaerotheriida are popular as pets. Some species commonly sold or kept include species of Archispirostreptus, Aphistogoniulus, Narceus, and Orthoporus.
Millipedes also appear in folklore and traditional medicine around the world. Many cultures ascribe millipede activity with coming rains. In the Yoruba culture of Nigeria, millipedes are used in pregnancy and business rituals, and crushed millipedes are used to treat fever, whitlow, and convulsion in children. In Zambia, smashed millipede pulp is used to treat wounds, and in the Bafia people of Cameroon millipede juice is used to treat earaches. In certain Himalayan Bhotiya tribes, dry millipede smoke is used to treat hemorrhoids. Native people in Malyasia use millipede secretions in poison-tipped arrows.
Approximately 12,000 species of millipede have been described, but the true number of species on earth has been estimated at up to 80,000. Millipedes are considered a mega-diverse yet understudied group, with inconsistent taxonomic effort over time.
The living members of the Diplopoda are divided into sixteen orders in two subclasses. 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, consisting of two infraclasses: the infraclass Pentazonia containing the short-bodied pill millipedes, and the infraclass Helminthomorpha (worm-like millipedes) containing the great majority of the species.
The higher-level classification of millipedes is presented below, based on Shear, 2011, and Shear & Edgecombe, 2010 (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. The placement and positions of extinct groups (†) known only from fossils is tentative and not fully resolved.
Class Diplopoda de Blainville in Gervais, 1844
- Subclass Penicillata Latrielle, 1831
- Order Polyxenida Verhoeff, 1934
- Subclass †Arthropleuridea (placed in Penicillata by some authors)
- Subclass Chilognatha Latrielle, 1802
- Order †Zosterogrammida Wilson, 2005 (Chilognatha incertae sedis)
- Infraclass Pentazonia Brandt, 1833
- Infraclass Helminthomorpha Pocock, 1887
- Superorder †Archipolypoda Scudder, 1882
- Order †Pleurojulida Schneider & Werneburg, 1998 (possibly sister to Colobognatha)
- Subterclass Colobognatha Brandt, 1834
- Subterclass Eugnatha Attems, 1898
- Superorder Juliformia Attems, 1926
- Superorder Nematophora Verhoeff, 1913
- Superorder Merochaeta Cook, 1895
- Order Polydesmida Pocock, 1887
- "Most leggy millipede rediscovered". BBC News. August 8, 2006.
- Shear, W. (2011). "Class Diplopoda de Blainville in Gervais, 1844. In: Zhang, Z.-Q. (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness". Zootaxa 3148: 159–164.
- "Fossil millipede found to be oldest land creature". CNN (from Reuters). 27 January 2004.
- M. G. Lockley & Christian Meyer (2013). "The tradition of tracking dinosaurs in Europe". Dinosaur Tracks and Other Fossil Footprints of Europe. Columbia University Press. pp. 25–52. ISBN 9780231504607.
- Sierwald, Petra; Bond, Jason E. (2007). "Current Status of the Myriapod Class Diplopoda (Millipedes): Taxonomic Diversity and Phylogeny". Annual Review of Entomology 52 (1): 401–420. doi:10.1146/annurev.ento.52.111805.090210. PMID 17163800.
- Lewis, J. G. E. (2008). The Biology of Centipedes (Digitally printed 1st paperback version. ed.). Cambridge: Cambridge University Press. pp. 110–111. ISBN 9780521034111.
- Robert D. Barnes (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 818–825. ISBN 0-03-056747-5.
- (2008). "Millipedes". In John L. Capinera. Encyclopedia of Entomology. Springer. pp. 2935–2397. ISBN 978-1-4020-6242-1.
- Mesibov, Robert. "Paranota". External Anatomy of Polydesmida. Retrieved 30 October 2013.
- Shelley, Rowland M. (1999). "Centipedes and Millipedes with Emphasis on North American Fauna". The Kansas School Naturalist 45 (3): 1–16.
- Blower, J. Gordon (1985). Millipedes: Keys and Notes for the Identification of the Species. London: Published for the Linnean Society of London and the Estuarine and Brackish-Water Sciences Association by E.J. Brill. ISBN 9004076980.
- Tamaris G. Pinheiro, Marinêz I. Marques & Leandro D. Battirola (2009). "Life cycle of Poratia salvator (Diplopoda: Polydesmida: Pyrgodesmidae)". Zoologia (Curitiba) 26 (4): 658–662. doi:10.1590/S1984-46702009000400010.
- Mesibov, Robert. "Gonopods". External Anatomy of Polydesmida. Retrieved 27 October 2013.
- Enghoff, Henrik; Akkari, Nesrine (2011). "A callipodidan cocoon (Diplopoda, Callipodida, Schizopetalidae)". International Journal of Myriapodology 5: 49–53. doi:10.3897/ijm.5.1995.
- Adis, Joachim (1986). "An "aquatic" millipede from a Central Amazonian inundation forest". Oecologia 68 (3): 347–349. doi:10.1007/BF01036737.
- Burrows, F.J.; D. F. Hales, A. J. Beattie (1994). "Aquatic millipedes in Australia: a biological enigma and a conservation saga". Australian Zoologist 29 (3-4): 213–216.
- Barber, A.D. (Ed) (2013). "World Database of Littoral Myriapoda". World Register of Marine Species. Retrieved 25 October 2013.
- Barker, G.M. (2004). "Millipedes (Diplopoda) and Centipedes (Chilopoda)(Myriapoda) as predators of terrestrial gastropods". In G.M. Barker (ed.). Natural enemies of terrestrial molluscs. Wallingford, Oxfordshire, UK: CAB International. pp. 405–426. ISBN 9780851990613.
- Weldon, Paul J.; Cranmore, Catherine F.; Chatfield, Jenifer A. (2006). "Prey-rolling behavior of coatis (Nasua spp.) is elicited by benzoquinones from millipedes". Naturwissenschaften 93 (1): 14–16. doi:10.1007/s00114-005-0064-z.
- Saporito, R. A.; Donnelly, M. A.; Hoffman, R. L.; Garraffo, H. M.; Daly, J. W. (2003). "A Siphonotid Millipede (Rhinotus) as the Source of Spiropyrrolizidine Oximes of Dendrobatid Frogs". Journal of Chemical Ecology 29 (12): 2781–2786. doi:10.1023/B:JOEC.0000008065.28364.a0.
- Eisner, T; Eisner, M; Attygalle, AB; Deyrup, M; Meinwald, J (1998). "Rendering the inedible edible: circumvention of a millipede's chemical defense by a predaceous beetle larva.". Proceedings of the National Academy of Sciences of the United States of America 95 (3): 1108–13. PMID 9448293.
- Ito, F. (1998). "Colony composition and specialized predation on millipedes in the enigmatic ponerine ant genus Probolomyrmex (Hymenoptera, Formicidae)". Insectes Sociaux 45 (1): 79–83. doi:10.1007/s000400050070.
- Herbert, D. G. (2000). "Dining on diplopods: remarkable feeding behaviour in chlamydephorid slugs (Mollusca: Gastropoda)". Journal of Zoology 251 (1): 1–5. doi:10.1111/j.1469-7998.2000.tb00586.x.
- Larsen, T. H; Lopera, A.; Forsyth, A.; Genier, F. (2009). "From coprophagy to predation: a dung beetle that kills millipedes". Biology Letters 5 (2): 152–155. doi:10.1098/rsbl.2008.0654.
- Murray S. Blum & J. Porter Woodring (1962). "Secretion of benzaldehyde and hydrogen cyanide by the millipede Pachydesmus crassicutis (Wood)". Science 138 (3539): 512–513. Bibcode:1962Sci...138..512B. doi:10.1126/science.138.3539.512. PMID 17753947.
- Yasumasa Kuwahara, Hisashi Ômura & Tsutomu Tanabe (2002). "2-Nitroethenylbenzenes as natural products in millipede defense secretions". Naturwissenschaften 89 (7): 308–310. Bibcode:2002NW.....89..308K. doi:10.1007/s00114-002-0328-9. PMID 12216861.
- Paul J. Weldon, Jeffrey R. Aldich, Jerome A. Klun, James E. Oliver & Mustapha Debboun (2003). "Benzoquinones from millipedes deter mosquitoes and elicit self-anointing in capuchin monkeys (Cebus spp.)". Naturwissenschaften 90 (7): 301–305. Bibcode:2003NW.....90..301W. doi:10.1007/s00114-003-0427-2. PMID 12883771.
- Ximena Valderrama, John G. Robinson, Athula B. Attygalle & Thomas Eisner (2000). "Seaonal anointment with millipedes in a wild primate: a chemical defense against insects". Journal of Chemical Ecology 26 (12): 2781–2790. doi:10.1023/A:1026489826714.
- Birkinshaw, Christopher R. (1999). "Use of Millipedes by Black Lemurs to Anoint Their Bodies". Folia Primatologica 70 (3): 170–171. doi:10.1159/000021691.
- Roncadori, R. W.; Duffey, S. S.; Blum, M. S. (1985). "Antifungal Activity of Defensive Secretions of Certain Millipedes". Mycologia 77 (2): 185–191. doi:10.2307/3793067.
- Thomas Eisner, Maria Eisner & Mark Deyrup (1996). "Millipede defense: use of detachable bristles to entangle ants" (PDF). Proceedings of the National Academy of Sciences 93 (20): 10848–10851. Bibcode:1996PNAS...9310848E. doi:10.1073/pnas.93.20.10848. PMID 8855269.
- G. Mason, H. Thompson, P. Fergin & R. Anderson (1994). "Spot diagnosis: the burning millipede". Medical Journal of Australia 160 (11): 718–726. PMID 8202008.
- S. Shpall & I. Frieden (1991). "Mahogany discoloration of the skin due to the defensive secretion of a millipede". Pediatric Dermatology 8 (1): 25–27. doi:10.1111/j.1525-1470.1991.tb00834.x. PMID 1862020.
- A. Radford (1976). "Giant millipede burns in Papua New Guinea". Papua New Guinea Medical Journal 18 (3): 138–141. PMID 1065155.
- A. Radford (1975). "Millipede burns in man". Tropical and Geographical Medicine 27 (3): 279–287. PMID 1103388.
- B. Hudson & G. Parsons (1997). "Giant millipede 'burns' and the eye". Transactions of the Royal Society of Tropical Medicine and Hygiene 91 (2): 183–185. doi:10.1016/S0035-9203(97)90217-0. PMID 9196764.
- Alagesan, P.; J. Muthukrishnan (2005). "Bioenergetics of the household pest, Xenobolus carnifex (Fabricius, 1775)". Peckiana 4: 3–14.
- Enghoff, Henrik; Kebapći, Ümit (2008). "Calyptophyllum longiventre (Verhoeff, 1941) invading houses in Turkey, with the first description of the male (Diplopoda: Julida: Julidae)". Journal of Natural History 42 (31-32): 2143–2150. doi:10.1080/00222930802196055.
- Ebregt, E.; Struik, P.C.; Odongo, B.; Abidin, P.E. (2005). "Pest damage in sweet potato, groundnut and maize in north-eastern Uganda with special reference to damage by millipedes (Diplopoda)". NJAS - Wageningen Journal of Life Sciences 53 (1): 49–69. doi:10.1016/S1573-5214(05)80010-7.
- Niijima, K. (2001). "[A millipede outbreak (Oxidus gracilis, Koch) stopped trains]". Edaphologia (in Japanese) 68: 43–46.
- Peckham, Matt (Sept. 4, 2013). "Millipedes – Yes, Millipedes – May Be Responsible for Australian Train Crash". Time Newsfeed. Time Magazine. Retrieved 31 October 2013.
- Stoev, Pavel; Zapparoli, Marzio; Golovatch, Sergei; Enghoff, Henrik; Akkari, Nesrine; Barber, Anthony (2010). "Myriapods (Myriapoda). Chapter 7.2. In: Roques et al. (Eds). Alien terrestrial arthropods of Europe". BIORISK – Biodiversity and Ecosystem Risk Assessment 4: 97–130. doi:10.3897/biorisk.4.51.
- Lewbart, Gregory A. (ed.). Invertebrate medicine (2nd ed.). Chichester, West Sussex: Wiley-Blackwell. p. 255. ISBN 9780470960783.
- Costa Neto, Eraldo M. (2007). "The perception of Diplopoda (Arthropoda, Myriapoda) by the inhabitants of the county of Pedra Branca, Santa Teresinha, Bahia, Brazil". Acta Biológica Colombiana 12 (2): 123–134.
- Lawal, O.A.; A.D. Banjo (2007). "Survey for the Usage of Arthropods in Traditional Medicine in Southwestern Nigeria". Journal of Entomology 4 (2): 104–112.
- Negi, C.S.; V.S. Palyal (2007). "Traditional Uses of Animal and Animal Products in Medicine and Rituals by the Shoka Tribes of District Pithoragarh, Uttaranchal, India". Studies on Ethno-Medicine 1 (1): 47–54.
- Brewer, Michael S.; Sierwald, Petra; Bond, Jason E.; Kolokotronis, Sergios-Orestis (2012). "Millipede Taxonomy after 250 Years: Classification and Taxonomic Practices in a Mega-Diverse yet Understudied Arthropod Group". PLoS ONE 7 (5): e37240. doi:10.1371/journal.pone.0037240.
- Julián Bueno-Villegas, Petra Sierwald & Jason E. Bond. "Diplopoda". In J. L. Bousquets & J. J. Morrone. Biodiversidad, taxonomia y biogeografia de artropodos de Mexico. pp. 569–599.
- Rowland M. Shelley. "Millipedes". Retrieved October 12, 2013.
- Shear, William A.; Edgecombe, Gregory D. (2010). "The geological record and phylogeny of the Myriapoda". Arthropod Structure & Development 39 (2-3): 174–190. doi:10.1016/j.asd.2009.11.002. PMID 19944188.
- Hoffman, R.L. (1963). "New genera and species of Upper Paleozoic Diplopoda". Journal of Paleontology 37 (1): 167–174. JSTOR 1301419.
|Wikimedia Commons has media related to Diplopoda.|
|Wikispecies has information related to: Diplopoda|
- Millipedes of North America in Myriapods: The World's Leggiest Animals
- Millipedes of Australia
- Milli-PEET: The Class Diplopoda- The Field Museum, Chicago IL
- World Checklist of Millipede Groups
- Video of a millipede from Thailand