Millipedes :
The millipede is a medium to large sized invertebrate that is found under rocks and in decaying logs all around the world. The millipede has a long and narrow body which is made up of segments.
The millipede is from the same family as the centipede, but the millipede generally has more legs for it's body length than the centipede. The average millipede has between 80 and 400 legs, not a thousand as the name suggests.
The millipede is found all over the world but is more common in the southern hemisphere where the millipede has been known to get to nearly 40cm long. Some species of millipede have a poisonous bite which they use to kill their prey before eating it.
Millipedes are most commonly found in the cooler, damper and darker places within their environment. Millipedes inhabit areas under rocks, in the leaf litter, in rotting logs and occasionally in burrows which are all known as micro-habitats.
The exact number of legs and segments that make up the body of the millipede, depend on the millipede species. However, all millipedes are made up in a similar way with the first sections of the millipede's body having one pair of legs and the later sections of two pairs of legs. The legs of millipede all work together and move in a wave-like motion.
The millipede is an omnivorous animal but primarily feeds on dead plant material and decaying matter on the forest floor. Millipedes are also known to eat some species of plants (that are alive0) and the larger species of millipede also hunt insects.
The millipede has a number of different predators in it's natural environment including birds,badgers, foxes and small rodents such as shrews and rats. When the millipede feels that it is in danger it curls up into a spiral and some species of millipede even release a disgusting smelling liquid that deters many of the animals that prey on the millipede.
The female millipede can lay up to 1,000 sticky eggs at once although the number of millipede eggs laid is usually closer to 500. When the baby millipedes hatch they only have 3 pairs of legs but they shed their skin as they grow. Each time the baby millipedes shed their skin they develop more body segments and legs.
Centipedes and Millipdes:
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MILLIPEDES | 10 Exciting Facts about Millipedes
Millipedes: The First Land Animals
Various species of millipedes
The centipede ("hundred legs") and millipede ("thousand legs") have various similarities, reflecting their biological relationship. Both, for instance, have common evolutionary roots, which extend back for more than 400 million years. Although related to lobsters, shrimp and crayfish, both are creatures of the land. Both have elongated, exoskeletal, segmented bodies. Both molt, extending the segments of their bodies. Both may live for several years. The centipede and the millipede also, however, have distinctive features.
Comparison of Anatomy and Appearance
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The centipede has an elongated, flattened, exoskeletal body
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The millipede, in most species, an elongated, rounded, exoskeletal body
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The centipede has, attached to its head, two relatively long segmented antenna that serve for feeling and smelling
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The centipede has, on the trunk segment immediately behind the head, two modified venomous legs that it uses to capture and kill prey
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The millipede has two comparatively short segmented antenna that function as acutely sensitive sensors
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The millipeded has no venomous legs.
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The centipede's trunk segments each have a single pair of legs
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The millipede's segments, two pairs of legs
Banded desert centipede. Note that each segment has a single pair of legs; the head, to the right, has segmented antenna; and the final segment, to the left, has modified legs for mating and defense.
Comparison of Defensive Strategies
The centipede uses two modified legs on the last segment of its body trunk and two modified venomous legs on the first segment for defense; the millipede uses glands that run along its trunk to produce - and sometimes squirt - noxious chemicals that discourage predators.
Comparison of Mobility
The centipede, with comparatively long legs, can move swiftly for short distances in a sprint to capture prey or elude predators; the millipede, with its short legs, can only move laboriously as it forages in soil and plant litter for food.
Comparison of Habitat
Both being susceptible to desiccation, a centipede seeks out stony crevices, fallen leaves, rotting logs, and the damp nooks in your home; the millipede favors decaying vegetation.
Comparison of Foraging
As a predator, the centipede feeds on animals as diverse as insects, spiders, reptiles and birds; as scavengers and herbivores, most species of millipede feed on decaying plant material and sprouting seedlings.
Reproduction
The centipede male deposits sperm bundles, entrusting females to find them and impregnate themselves. By contrast, the millipede male and female join in mating. Centipede and millipede females both typically lay their eggs in underground nests. The females of some centipede species abandon their eggs, leaving the broods to manage on their own; the females of other species nurtures their broods until the offspring can manage on their own. The females of all the various millipede species remain with their eggs until they hatch, and they nurture the offspring until they can manage on their own.
Millipede vs Centipede!
Millipedes are arthropods in the class Diplopoda, which is characterised by having two pairs of jointed 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 or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a ball. Although the name "millipede" derives from the Latin for "thousand feet", no known species has 1,000; the record of 750 legs belongs to Illacme plenipes. There are approximately 12,000 named species classified into sixteen orders and around 140 families, making Diplopoda the largest class of myriapods, an arthropod group which also includes centipedes and other multi-legged creatures.
Most millipedes are slow-moving detritivores, eating decaying leaves and other dead plant matter. Some eat fungi or suck plant fluids, and a small minority are predatory. Millipedes are generally harmless to humans, although some can become household or garden pests, especially in greenhouses where they can cause severe damage to emergent seedlings. Most millipedes defend themselves with a variety of defensive chemicals secreted from pores along the body, although the tiny bristle millipedes are covered with tufts of detachable bristles. Reproduction in most species is carried out by modified male legs called gonopods, which transfer packets of sperm to females.
Millipedes are some of the oldest known land animals, first appearing in theSilurian period. Some members of prehistoric groups grew to over 2 m (6 ft 7 in), while the largest modern species reach maximum lengths of 27 to 38 cm (11 to 15 in). The longest extant species is the giant African millipede (Archispirostreptus gigas).
Among myriapods, millipedes have traditionally been considered most closely related to the tiny pauropods, although some molecular studies challenge this relationship. Millipedes can be distinguished from the somewhat similar but only distantly related centipedes (class Chilopoda), which move rapidly, arecarnivorous, and have only a single pair of legs on each body segment. The scientific study of millipedes is known as diplopodology, and a scientist who studies them is called a diplopodologist.
Characteristics :
Millipedes come in a variety of body shapes and sizes, ranging from 2 mm (0.08 in) to around 35 cm (14 in) in length,[9] and can have as few as eleven to over one hundred segments.[10] They are generally black or brown in colour, although there are a few brightly coloured species, and some have aposematiccolouring to warn that they are toxic.[2] Species of Motyxia produce cyanide as a chemical defence and are bioluminescent.[11]
Body styles vary greatly between major millipede groups. In the basal subclassPenicillata, consisting of the tiny bristle millipedes, the exoskelton is soft and uncalcified, and is covered in prominent setae or bristles. All other millipedes, belonging to the subclass Chilognatha, have a hardened exoskeleton. The chilognaths are in turn divided into two infraclasses: the Pentazonia, containing relatively short-bodied groups such as pill millipedes, and the Helminthomorpha("worm-like" millipedes), which contains the vast majority of species, and the long, many-segmented body types familiar to most people.[12][13]
Head:
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").[14]
The head contains a single pair of antennae with seven or eight segments and a group of sensory cones at the tip.[14] 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,[14] but they also occur in some centipedes, and are possibly used to measure humidity or light levels in the surrounding environment.[15]
An assortment of millipedes (not to scale)
Scientific classification:
Kingdom : Animalia
Phylum : Arthropoda
Subphylum : Myriapoda
Class : Diplopoda
De Blainville in Gervais, 1844
Subclasses :
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Penicillata
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Chilognatha
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Arthropleuridea (extinct)
Diversity :
16 orders, c. 12,000 species
Etymology and names :
The scientific name "Diplopoda" comes from the Greek words διπλοῦς (diplous), "double" and ποδός (podos), "foot", referring to the appearance of two legs on most segments, as described below. The common name "millipede" is a compound word formed from the Latin roots mille ("thousand") and ped ("foot"). The term "millipede" is widespread in popular and scientific literature, but among North American scientists, the term "milliped" (without the terminal e) is also used.[1] Other vernacular names include "thousand-legger" or simply "diplopod".[2]
Evolution :
Millipedes are among the first animals to have colonised land during the Silurian geologic period.[3] Early forms probably ate mosses and primitive vascular plants. There are two major groups of entirely extinct millipedes: theArchipolypoda ("ancient, many-legged ones") which contain the oldest known terrestrial animals, and Arthropleuridea, which contain the largest known land invertebrates. The earliest known land creature, Pneumodesmus newmani, was a 1 cm (0.4 in) long archipolypodan that lived 428 million years ago in the upper Silurian, and has clear evidence ofspiracles (breathing holes) attesting to its air-breathing habits.[4][5] During the Upper Carboniferous(340 to 280 million years ago), Arthropleura became the largest known land-dwelling invertebrate of all time, reaching lengths of at least 2 m (6 ft 7 in).[6] Millipedes also include the earliest evidence of chemical defense, as someDevonian fossils have defensive gland openings called ozopores.[5] 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.[7]
Few species of millipede are at all widespread; they have very poor dispersal abilities, depending as they do on terrestrial locomotion and humid habitats. These factors have favored genetic isolation and rapid speciation, producing many lineages with restricted ranges.
Body :
Millipede bodies may be flattened or cylindrical, and are composed of numerousmetemeric segments, each with an exoskeleton consisting of five chitinous plates: a single plate above (the tergite), one at each side (pleurites), and a plate on the underside (sternite) where the legs attach. 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.[10] Because they lack a waxy cuticle, millipedes are susceptible to water loss and must spend most of their time in moist or humid environments.[16]
Representative body types of the Penicillata (top), Pentazonia (middle), and Helminthomorpha (bottom)
Anterior anatomy of a generalized helminthomorph millipede
Paranota of polydesmidan (left) and platydesmidan millipedes
The first segment behind the head is legless and known as a collum (from the Latin for neck or collar). The second, third, and fourth body segments bear a single pair of legs each and are known as "haplosegments", from the Greek haplo, "single" (the three haplosegments are sometimes referred to as a "thorax"[4]). 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" or "body ring" are often used interchangeably to refer to both haplo- and diplosegments. The final segment is known as the telson and consists of a legless preanal ring, a pair of anal valves (closeable plates around the anus), and a small scale below the anus.[14][10]
Millipedes in several orders have keel-like extensions of the body-wall known as paranota, which can vary widely in shape, size, and texture; modifications include lobes, papillae, ridges, crests, spines and notches.[2] Paranota may allow millipedes to wedge more securely into crevices, protect the legs, or make the millipede more difficult for predators to swallow.[17]
The legs are composed of seven segments, and attach on the underside of the body. The legs of an individual are generally rather similar to each other, although often longer in males than females, and males of some species may have a reduced or enlarged first pair of legs.[18] The most conspicuous leg modifications are involved in reproduction, discussed below. Despite the common name, no millipede has been discovered with 1,000 legs: common species have between 34 and 400 legs, and the record is held by Illacme plenipes, with individuals possessing up to 750 legs – more than any other creature on Earth.[19]
Millipede eyes consist of a number of simple flat-lensed ocelli arranged in a group or patch on each side of the sides of the head. These patches are also called ocular fields or ocellaria. Many species of millipedes, including the entire order Polydesmida and cave-dwelling millipedes such as Causeyella and Trichopetalum, have secondarily lost their eyes and are completely blind.[9]
Growth stages of Nemasoma(Nemasomatidae), which reaches reproductive maturity in stage V
A female Illacme plenipes with 618 legs (309 pairs)
Internal organs :
Millipedes breathe through two pairs of spiracles located ventrally on each segment near the base of the legs.[20] 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.[10]
Reproduction and growth :
Millipedes show a diversity of mating styles and structures. In the basal orderPolyxenida (bristle millipedes), mating is indirect: males depositspermatophores onto webs they secrete with special glands, and the spermatophores are subsequently picked up by females.[20] In all other millipede groups, males possess one or two pairs of modified legs calledgonopods which are used to transfer sperm to the female during copulation. The location of the gonopods differs between groups: in males of thePentazonia they are located at the rear of the body and known as telopods and may also function in grasping females, while in the Helminthomorpha – the vast majority of species – they are located on the seventh body segment.[14] A few species are parthenogenetic, having few, if any, males.[21]
Gonopods occur in a diversity of shapes and sizes, and in the range from closely resembling walking legs to complex structures quite unlike legs at all. In some groups, the gonopods are kept retracted within the body, while in others they project forward parallel to the body. Gonopod morphology is the predominant means of determining species among millipedes: the structures may differ greatly between closely related species but very little within a species.[22] The gonopods develop gradually from walking legs through successive moults until reproductive maturity.[23]
The genital openings (gonopores) of both sexes are located on the underside of the third body segment (near the second pair of legs) and may be 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 calledcyphopods or vulvae, which are covered by a small hood-like cover, and are used to store the sperm after copulation.[10] The cyphopod morphology can also be used to identify species. Millipede sperm is aflagellate (lacks a flagellum), a unique trait among myriapods.[14]
In all except the bristle millipedes, copulation occurs with the two individuals facing one another. Copulation may be preceded by male behaviors such as tapping with antennae, running along the back of the female, offering glandular secretions, which the female consumes, or in the case of some pill-millipedes,stridulation or "chirping".[24] During copulation in most millipedes, the male positions his seventh segment in front of the female's third segment, and may insert his gonopods to extrude the vulvae before bending his body to deposit sperm onto his gonopods and reinserting the "charged" gonopods into the female.[18]
Epibolus pulchripes mating; the male is at right
The gonopods of Nipponesmus shirinensis are quite unlike walking legs.
Left gonopod of Oxidus gracilis.False color SEM image, scale bar: 0.2 mm
Living groups
The history of scientific millipede classification began with Carl Linnaeus, who in his 10th edition of Systema Naturae, 1758, named seven species of Julus as "Insecta Aptera" (wingless insects).[76] In 1802, the French zoologist Pierre André Latreille proposed the name Chilognatha as the first group of what are now the Diplopoda, and in 1840 the German naturalist Johann Friedrich von Brandtproduced the first detailed classification. The name Diplopoda itself was coined in 1844 by Henri Marie Ducrotay de Blainville. In the following decades, millipede taxonomy was driven by relatively few researchers at any given time, with major contributions by Carl Attems, Karl Verhoeff and Ralph V. Chamberlin, who each described over 1,000 species, as well as Orator F. Cook, Filippo Silvestri, R. I. Pocock, and Henry W. Brölemann.[14] The 50-year period from 1890 to 1940, when the seven researchers above were working, was a period when the science of diplopodology flourished: rates of species descriptions during this period was on average the highest in history, sometimes exceeding 300 per year.[75]
Females lay from ten to 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.[10] In most species, the female abandons the eggs after they are laid, but some species in the orders Platydesmida and Stemmiulidaprovide parental care for eggs and young.[20]
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,[25] which they may also use to wait out dry weather, and most species eat the shed exoskeleton after moulting. The adult stage- when individuals become reproductively mature- is generally reached in the final moult stage, which varies between species and orders, although some species continue to moult after adulthood. Furthermore, some species alternate between reproductive and non-reproductive stages after maturity, a phenomenon known as periodomorphosis, in which the reproductive structures regress during non-reproductive stages.[21] Millipedes may live from one to ten years, depending on species.[10]
Ecology :
Habitat and distribution
Millipedes occur on all continents except Antarctica, and occupy almost all terrestrial habitats, ranging as far north as the Arctic Circle in Iceland, Norway, and Central Russia, and as far south as Santa Cruz Province, Argentina.[26][27]Millipedes are typically forest floor dwellers, occurring in leaf litter, dead wood, or soil, with a preference for humid conditions. In temperate zones, millipedes are most abundant in moist deciduous forests, and may reach densities of over 1,000 individuals per square metre. Other habitats include coniferous forests, deserts, caves, and alpine ecosystems.[20][27] Some species can survive freshwater floods and live submerged underwater for up to 11 months.[28][29] A few species occur near the seashore and can survive in somewhat salty conditions.[21][30]
Burrowing:
The diplosegments of millipedes have evolved in conjunction with their burrowing habits, and nearly all millipedes adopt a mainly subterranean lifestyle. They use three main methods of burrowing; bulldozing, wedging and boring. Members of the orders Julida, Spirobolida and Spirostreptida simply lower their heads and barge their way into the substrate, the collum being the portion of their exoskeleton that leads the way. Flat-backed millipedes in the orderPolydesmida tend to insert their front end, like a wedge, into a horizontal crevice, and then widen the crack by pushing upwards with their legs, the paranota in this instance constituting the main lifting surface. Boring is used by members of the order Polyzoniida. These have smaller segments at the front and increasingly large ones further back; they propel themselves forward into a crack with their legs, the wedge-shaped body widening the gap as they go. Some millipedes have adopted an above-ground lifestyle and lost the burrowing habit. This may be because they are too small to have enough leverage to burrow, or because they are too large to make the effort worthwhile, or in some cases because they move relatively fast (for a milipede) and are active predators.[2]
Diet:
The majority of millipedes are detritivores and feed on decomposing vegetation, faeces, or organic matter mixed with soil. They often play important roles in the breakdown and decomposition of leaf litter: estimates of consumption rates for individual species range from 1 to 11 percent of all leaf litter, depending on species and region, and collectively millipedes may consume nearly all the leaf litter in a region. The leaf litter is fragmented in the millipede gut and excreted as pellets of leaf fragments, algae, fungi, and bacteria, which facilitates decomposition by the microorganisms.[18] Where earthworm populations are low in tropical forests, millipedes play an important role in facilitating microbial decomposition of the leaf litter.[2] Some millipedes are herbivorous, feeding on living plants, and some species can become serious pests of crops. Millipedes in the order Polyxenida graze algae from bark, andPlatydesmida feed on fungi.[14] A few species are omnivorous or occasionally carnivorous, feeding on insects, centipedes, earthworms, or snails.[10][31] Some species have piercing mouth parts that allow them to feed on plant juices.[20]
Predators and parasites :
Millipedes are preyed on by a wide range of animals, including various reptiles,amphibians, birds, mammals, and insects.[14] Mammalian predators such ascoatis and meerkats roll captured millipedes on the ground to deplete defensive secretions and rub them off the body before consuming,[32] while certain poison dart frogs are believed to incorporate the toxic compounds of millipedes into their own defenses.[33] Several invertebrates have specialized behaviors or structures to feed on millipedes, including larval glowworm beetles,[34] Probolomyrmexants,[35] chlamydephorid slugs,[36] and predaceous dung beetles of the generaSceliages and Deltochilum.[37][38] A large subfamily of assassin bugs, theEctrichodiinae with over 600 species, has specialized in preying upon millipedes.[39]
Parasites of millipedes include nematodes, phaeomyiid flies, and acanthocephalans.[14]
A Sceliages beetle transporting a millipede carcass
Defence mechanisms :
Further information: Antipredator adaptation
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 exoskeleton.
Many species also emit various foul-smelling liquid secretions through microscopic holes called ozopores (the openings of "odoriferous" or "repugnatorial glands"), along the sides of their bodies as a secondary defence. Among the many irritant and toxic chemicals found in these secretions are alkaloids, benzoquinones, phenols,terpenoids, and hydrogen cyanide.[40][41] 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.[42][43][44]Some of these defensive compounds also show antifungal activity.[45]
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.[46]
Other inter-species interactions:
Some millipedes form mutualistic relationships with organisms of other species, in which both species benefit from the interaction, or commensal relationships, in which only one species benefits while the other is unaffected. Several species form close relationships with ants, a relationship known as myrmecophily, especially within the family Pyrgodesmidae (Polydesmida), which contains "obligate myrmecophiles"- species which have only been found in ant colonies. More species are "facultative myrmecophiles", being non-exclusively associated with ants, including many species of Polyxenida that have been found in ant nests around the world.[47]
Many millipede species have commensal relationships with mites of the ordersMesostigmata and Astigmata. Many of these mites are believed to be phoretic rather than parasitic, which means that they simply use the millipede host as a means of dispersal.[48][49]
A novel interaction between millipedes and mosses was described in 2011, in which individuals of the newly discovered Psammodesmus bryophorus was found to have up to ten species living on its dorsal surface, in what may provide adventitious camouflage for the millipede and increased dispersal for the mosses.[50][51]
Interactions with people :
Millipedes generally have little impact to human economic or social well-being, especially in comparison with insects, although locally can be a nuisance or agricultural pest. Millipedes do not bite, and their defensive secretions 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.[52][53][54][55]Eye exposures to these secretions causes general irritation and potentially more severe effects such as conjunctivitisand keratitis.[56] First aid consists of flushing the area thoroughly with water; further treatment is aimed at relieving the local effects.
Psammodesmus bryophoruscamouflaged with symbioticmosses
Some millipedes are considered household pests, including Xenobolus carnifex which can infest thatched roofs in India,[57] and Ommatoiulus moreleti, which periodically invades homes in Australia. Other species exhibit periodicalswarming behaviour, which can result in home invasions,[58] crop damage,[59]and train delays when the tracks become slippery with the crushed remains of hundreds of millipedes.[18][60][61] Some millipedes can cause significant damage to crops: the spotted snake millipede (Blaniulus guttulatus) is a noted pest of sugar beets and other root crops, and as a result is one of the few millipedes with a common name.[21]
An aggregation of millipedes
Some of the larger millipedes in the orders Spirobolida, Spirostreptida, andSphaerotheriida are popular as pets.[62] Some species commonly sold or kept include species of Archispirostreptus,Aphistogoniulus, Narceus, and Orthoporus.[63]
Millipedes appear in folklore and traditional medicine around the world. Many cultures associate millipede activity with coming rains.[64] In the Yoruba culture of Nigeria, millipedes are used in pregnancy and business rituals, while crushed millipedes are used to treat fever, whitlow, and convulsion in children.[65] In Zambia, smashed millipede pulp is used to treat wounds, and in the Bafia people of Cameroon millipede juice is used to treat earaches.[64] In certain HimalayanBhotiya tribes, dry millipede smoke is used to treat hemorrhoids.[66] Native people in Malaysia use millipede secretions in poison-tipped arrows.[64] The secretions of Spirobolus bungii have even been reported to inhibit division of human cancer cells.[67] The only reported usage of millipedes as food by humans comes from the Bobo people of Burkina Faso, who consume boiled, dried millipedes in tomato sauce.[68] In popular music (including names of albums, songs, and artists) millipedes are poorly represented compared to other arthropods.[69]
Millipedes have also inspired and played roles in scientific research. In 1963, J. N. Siddal of the Canadian "Terrain Research Unit" designed a walking vehicle with 36 legs, said to have been inspired by a study of millipede locomotion.[70] Experimental robots have had the same inspiration,[71][72] in particular when heavy loads are needed to be carried in tight areas involving turns and curves.[73] In biology, some authors have advocated millipedes as model organisms for the study of arthropod physiology and the developmental processes controlling the number and shape of body segments.[18]
Classification :
The science of millipede biology and taxonomy is called diplopodology: the study of diplopods. Approximately 12,000 millipede species have been described, but estimates of the true number of species on earth range from 15,000–20,000[75] to as high as 80,000.[14]
The living members of the Diplopoda are divided into sixteen orders in two subclasses.[74] The basal subclass Penicillata contains a single order, Polyxenida (bristle millipedes). All other millipedes belong to the subclass Chilognatha consisting of two infraclasses: the infraclass Pentazoniacontaining the short-bodied pill millipedes, and the infraclass Helminthomorpha (worm-like millipedes) containing the great majority of the species.[12][13]
Octoglena sierra(Colobognatha, Polyzoniida)
Anadenobolus monilicornis(Juliformia, Spirobolida)
Harpaphe haydeniana(Polydesmida)
Approximate relative diversity ofextant millipede orders, ranging from ca. 3,500 species of Polydesmida to 2 species of Siphoniulida.[74]
In 1971, Dutch biologist C. A. W. Jeekel published a comprehensive listing of all known millipede genera and families described between 1758 and 1957 in hisNomenclator Generum et Familiarum Diplopodorum, a work credited as launching the "modern era" of millipede taxonomy.[77][78] In 1980, American biologist Richard L. Hoffman published a classification of millipedes which recognized the Penicillata, Pentazonia, and Helminthomorpha,[79] and the first phylogenetic analysis of millipede orders using modern cladistic methods was published in 1984 by Henrik Enghoff of Denmark.[80] A 2003 classification by American myriapodologist Rowland Shelley is similar to classification originally proposed by Verhoeff, and remains the currently accepted classification scheme (shown below), despite more recent molecular studies which propose a number of conflicting relationships.[5][14] A 2011 summary of millipede family diversity by William A. Shear placed the order Siphoniulida within the larger group Nematomorpha.[74]
References :
Click here to see the references in the main article on Wikipedia
External links :
- Millipedes at the Encyclopedia of Life
-Milli-PEET: The Class Diplopoda – The Field Museum, Chicago
- Millipedes of North America in Myriapods: The World's Leggiest Animals
- Millipedes of Australia
- Diplopoda: Guide to New Zealand Soil Invertebrates – Massey University
- SysMyr, a myriapod taxonomy database
-British Myriapod & Isopod Group
Diplopoda
Penicillata - Polyxenida
Chilognatha
Limacomorpha - Glomeridesmida
Eugnatha
Fossil record :
In addition to the 16 living orders, there are 9 extinct orders and one superfamily known only from fossils. The relationship of these to living groups and to each other is controversial. The extinct Arthropleuridea was long considered a distinct myriapod class, although work in the early 21st century established the group as a subclass of millipedes.[81][82][83] Several living orders also appear in the fossil record. Below are two proposed arrangements of fossil millipede groups.[5][14] Extinct groups are indicated with a dagger (†). The extinct order Zosterogrammida, a chilognath of uncertain position,[5] is not shown.
For more information about the fossil recirds species click here
Outline of classification:
For more details on this topic, see List of millipede families.
The higher-level classification of millipedes is presented below, based on Shear, 2011,[74] and Shear & Edgecombe, 2010[5] (extinct groups). Recent cladistic and molecular studies have challenged the traditional classification schemes, above and in particular the position of the orders Siphoniulida and Polyzoniida is not yet well established.[14] The placement and positions of extinct groups (†) known only from fossils is tentative and not fully resolved.[5][14] After each name is listed the author citation: the name of the person who coined the name or defined the group, even if not at the current rank.
Class Diplopoda de Blainville in Gervais, 1844
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Subclass Penicillata Latrielle, 1831
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Order Polyxenida Verhoeff, 1934
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Subclass †Arthropleuridea (placed in Penicillata by some authors)[5]
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Order †Arthropleurida Waterlot, 1934
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Order †Eoarthropleurida Shear & Selden, 1995
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Order †Microdecemplicida Wilson & Shear, 2000
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Subclass Chilognatha Latrielle, 1802
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Order †Zosterogrammida Wilson, 2005 (Chilognatha incertae sedis)[5]
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Infraclass Pentazonia Brandt, 1833
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Order †Amynilyspedida Hoffman, 1969
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Superorder Limacomorpha Pocock, 1894
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Order Glomeridesmida Cook, 1895
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Superorder Oniscomorpha Pocock, 1887
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Order Glomerida Brandt, 1833
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Order Sphaerotheriida Brandt, 1833
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Infraclass Helminthomorpha Pocock, 1887
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Superorder †Archipolypoda Scudder, 1882
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Order †Archidesmida Wilson & Anderson 2004
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Order †Cowiedesmida Wilson & Anderson 2004
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Order †Euphoberiida Hoffman, 1969
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Order †Palaeosomatida Hannibal & Krzeminski, 2005
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Order †Pleurojulida Schneider & Werneburg, 1998 (possibly sister to Colobognatha)[14]
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Subterclass Colobognatha Brandt, 1834
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Order Platydesmida Cook, 1895
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Order Polyzoniida Cook, 1895
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Order Siphonocryptida Cook, 1895
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Order Siphonophorida Newport, 1844
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Subterclass Eugnatha Attems, 1898
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Superorder Juliformia Attems, 1926
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Order Julida Brandt, 1833
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Order Spirobolida Cook, 1895
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Order Spirostreptida Brandt, 1833
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Superfamily †Xyloiuloidea Cook, 1895 (Sometimes aligned with Spirobolida)[84]
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Superorder Nematophora Verhoeff, 1913
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Order Callipodida Pocock, 1894
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Order Chordeumatida Pocock 1894
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Order Stemmiulida Cook, 1895
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Order Siphoniulida Cook, 1895
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Superorder Merocheta Cook, 1895
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Order Polydesmida Pocock, 1887
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Relation to other myriapods
Although the relationships of millipede orders are still the subject of debate, the class Diplopoda as a whole is considered a monophyletic group of arthropods: all millipedes are more closely related to each other than to any other arthropods. Diplopoda is a class within of the arthropod subphylumMyriapoda, the myriapods, which includes centipedes (class Chilopoda) as well as the lesser-known pauropods (class Pauropoda) and symphylans (class Symphyla). Within myriapods, the closest relatives or sister group of millipedes has long been considered the pauropods, which also have a collum and diplosegments.[14]
Pauropods are thought to be the closest relative of millipedes.
Distinction from centipedes :
The differences between millipedes and centipedes are a common question from the general public.[20] Both groups of myriapods share similarities, such as long, multi-segmented bodies, many legs, a single pair of antennae, and the presence of Tömösváry organs, but have many differences and distinct evolutionary histories, as the most recent common ancestor of centipedes and millipedes lived around 450 to 475 million years ago in the Silurian.[85]
A representative millipede and centipede (not necessarily to scale)
Millipede and centipede differences:
