The name “centipede” means “hundred feet,” and chilopods are commonly referred to as “hundred-leggers.” Unlike millipedes, this term is literally correct as some species in the order Geophilomorpha do have over 100 legs, the most known being 382 (191 pairs) on Gonibregmatus plurimipes, occurring in Fiji in the Pacific Ocean. Centipede segments possess one pair or two legs that, except for the last pair, arise laterally, are clearly visible along the sides of the body, and function in locomotion. The ultimate or last legs extend backwards beyond the caudal extremity of the body and are not used for locomotion; they may be modified for sensory, defensive, or prey-capture functions.
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The Chilopoda is not as diverse and speciose a taxon as the Diplopoda. It comprises only five living orders with around 2,800 described species out of an estimated global fauna of approximately 8,000 species (Adis & Harvey 2000); by contrast, millipedes have over three times as many orders (16) and 10 times as many estimated species (80,000). The Chilopoda also is not as ancient a class, as its fossil history dates back to the late Silurian period of the Paleozoic era, ca. 410 million years ago (Shear 1992). Centipedes occur sporadically north of the Arctic Circle, inhabit all subarctic environments, and are abundant in xeric desert biotopes, where they are one of the most commonly recognized terrestrial invertebrates. They are exclusively carnivores, preying primarily on smaller arthropods, but large-bodied representatives of the order Scolopendromorpha are known to attack and feed on bats, mice, & other small mammals, snakes, frogs & toads, and birds. Four of the five orders contain agile, fast-moving forms that are adapted for speed; the exception is the Geophilomorpha, whose species move slowly and burrow in the substrate in a manner similar to earthworms, by elongating and contracting their bodies.
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Centipedes are flexible, “opisthogoneate” arthropods (reproductive tracts open at the caudal end of the body) with two anatomical divisions, a head and trunk. Except for the order Scutigeromorpha, they are dorsoventrally (top-to-bottom) flattened, and all chilopods possess “poison claws” (also called “prehensors” or “forcipules”) beneath the head with which they bite prey and potential predators including other centipedes; these structures possess internal glands that secrete venom that is toxic to their prey. Biting and injecting venom is the primary method of defense, but centipedes also employ camouflage, “aposematic” (warning) coloration, and “autotomizing” appendages (detaching those grasped by predators and then outrunning them). A few species also produce defensive secretions, and larger ones appear to have glands in their legs, as merely walking on skin can produce inflamed puncture wounds. Centipedes exhibit two basic body forms and lack the great array of ornamentations that exist in the Diplopoda. Some species are uniformly brown or dark gray in color while others are yellow, orange, red, blue, green, violet, or black; still others possess transverse stripes along the caudal margins of the “tergites” (dorsal plates), and the Indian species, Scolopendra hardwicki, displays alternating orange/red and black tergites.
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The principal autapomorphy (unique derived character) of the Chilopoda is the “poison claws,” which, though associated with the head, are not mouthparts and are actually appendages of the first segment. The centipedes that are adapted for speed encounter a difficulty, because any long, slender object that moves swiftly forward generates side-to-side undulations that counter this motion (like the swaying of a train), so centipedes have developed anatomical modifications that dampen or reduce the undulations. One of these is “tergite heteronomy,” with alternating short and long plates (well developed in Lithobiomorpha, poorly developed in Scolopendromorpha), which shortens the body, thereby reducing the undulations, while maintaining the same number of legs to propel the animal rapidly forward. The other is “tergal fusion,” shown by Scutigeromorpha, which strengthens the body and makes it more rigid at the positions where undulations develop. The coxae (basal articles) of the last legs in geophilomorphs and scolopendromorphs, and the last few legs in lithobiomorphs, possess variable numbers of “coxal pores” that lead to internal glands that are absent from scutigeromorphs. These glands are thought to function as osmoregulatory organs, excreting water under wet conditions and absorbing it in dry environments.
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In the Scutigeromorpha, the long-legged and swift-moving European species, Scutigera coleoptrata, has been widely introduced into North America and is often encountered in houses in cool, moist places like drains, sinks, bathtubs, and cellars. Additionally, five nominal species have been proposed for forms in Texas and Arizona: S. linceci, homa, dorothea, phana, and buda. Würmli (1973) placed S. homa, dorothea, phana, and buda in synonymy under S. linceci, but they warrant further study because type specimens do not exist for most of these, particularly S. linceci, described by Wood (1867) from an unspecified site in Texas. If S. linceci is a valid species, a supportive neotype specimen is mandatory, so a thorough scientific investigation of these additional North American scutigeromorphs constitutes a worthy research project. Shelley (2002) surveyed the Scolopendromorpha across the continent and documented an indigenous fauna of eight genera and 21 species. North America is thus the only continent in which this order has been thoroughly studied, and the Scolopendromorpha is one of the few invertebrate orders to have been surveyed across it. Another European centipede, Cryptops hortensis, a small-bodied scolopendromorph, has been widely introduced and is now established in urban environments in the US and Canada, and six additional exogenous species (and one genus) have been encountered occasionally, particularly at ports (Shelley & Edwards 2004, Shelley et al. 2005). The higher taxa (families and orders) are distinguished primarily by the number of segments and legs, the lengths of the appendages, the presence or absence of segmental modifications, the profile and general body form, and the configuration of the head. Determinations of centipede genera and species are more difficult than in millipedes because they lack the all important gonopods and telopods found in chilognath Diplopoda. Many centipede genera and species are superficially similar such that only an experienced taxonomist can distinguish one from another. Taxonomically important characters include spinulation of the legs, especially the last pair, setation on the antennae, the position and arrangement of tergal sulci & sutures, and the size and configuration of the “coxosternal tooth plates,” which extend anteriorly between the bases of the prehensors.
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The subclass Notostigmophora includes only one order, Scutigeromorpha, which contains three families, around 16 genera, and 80 described species out of an estimated global fauna of 100-150 species (Adis & Harvey 2000). Scutigeromorphs are relatively short-bodied centipedes in which the “spiracles” (openings to the trachea or respiratory system) are located middorsally. Adults possess 15 pairs of very long legs that become progressively longer caudally, and the antennae are very long and whip-like, consisting of two basal articles and a long flagellum with hundreds of very short articles. The head is hemispherical or “dome shaped” and possesses two compound eyes that differ structurally from those of insects; the trunk is not dorsoventrally flattened, and while adults have 15 “sterna” (ventral plates), there are only seven large terga (dorsal plates) because of “tergal fusion.” Scutigeromorphs demonstrate “anamorphic” development (they hatch from the egg with less than the full adult complement of legs and segments, and add legs & segments, and grow larger, at subsequent molts until they reach this number) and hatch with only four segments and leg pairs. They are extremely fast, agile, and delicate centipedes that are difficult to catch and collect intact; the legs are readily autotomized, and few museum specimens possess all 15 pairs in good condition.
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The remaining four orders, containing the vast majority of species, belong to the subclass Pleurostigmophora, which comprises dorsoventrally flattened centipedes in which the spiracles are located laterally and the appendages are not prolonged; eyes, when they exist, are simple ocelli on both sides of the head. Two orders, Lithobiomorpha & Craterostigmomorpha, demonstrate “anamorphic” development, while Scolopendromorpha & Geophilomorpha are “epimorphic” (hatchlings emerge from the egg with the full adult complement of legs & segments and grow larger at subsequent molts). In the “epimorphic” orders, the eggs and early stadia are “brooded” by females, which curl or hump their bodies over the egg masses, whereas eggs are laid singly and not brooded in Lithobiomorpha. According to Lewis (1981a), brooding occurs in the anamorphic Craterostigmomorpha, but little is known about life history and development in this order.
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The Lithobiomorpha comprises short-bodied forms with 15 pairs of legs and segments in adults, and 7 (rarely 6 or 8) in hatchlings. They exhibit strong tergite heteronomy, as tergites 1, 3, 5, 7, 8, 10, 12, and 14 are much longer than those of the other segments. Lithobiomorphs typically possess ocelli, but a few, mostly cavernicolous species, have lost them. The order comprises two families that are distinguished by the presence of setae alone on the legs (Henicopidae) or spines/spurs plus setae (Lithobiidae). There are 95 genera, and ca. 1,500 species have been described from an estimated global fauna of >2,000 species (Adis & Harvey 2000).
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The Craterostigmomorpha is the most geographically restricted and least-diverse order. It occurs only in Tasmania (not Australia proper) & New Zealand, and was thought to be restricted to the South Island of the latter until Shelley (2002) cited it from the North Island based on a discovery by G. D. Edgecombe. The order comprises only one family, one genus, and one described species (Craterostigmus tasmanianus); there is at most only one other species, currently undescribed, as some specialists believe the form in New Zealand is specifically distinct. Craterostigmomorphs have 15 pairs of legs and sterna, but there appear to be 21 tergites (plus a terminal structure) because tergites 3, 5, 7, 8, 10, and 12 are divided. There is one pair of ocelli; the head capsule is longer than wide; and the “poison claws” extend well in front of the latter and are clearly visible in dorsal view (from above). The terminal structure is bizarre, as it consists of two valves that are fused dorsally but meet in a longitudinal slit ventrally; its function is unknown.
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contains the most readily recognized chilopods and exhibit the body
form that most people envision when centipedes are mentioned. There
are three families – Scolopendridae, Scolopocryptopidae, and
Cryptopidae – based in part on the presence (Scolopendridae) or
absence (Scolopocryptopidae and Cryptopidae) of four ocelli on each
side of the cephalic plate and the number of segments (21 in
Scolopendridae [except for Scolopendropsis, which has 23] and
Cryptopidae, and 23 in Scolopocryptopidae).
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The final centipede order, Geophilomorpha, is unique in several ways. It is the only order whose species are not adapted for speed and instead burrow slowly in the substrate; it is the only one in which species reach the magic figure of 100 legs (the number in this order, always an odd number of pairs, ranging from 54 [27 pairs] to 382 [191 pairs]); and it is also the only order with appreciable diversity, as there are currently 14 component families, 180 genera, and ca. 1,100 described species out of an estimated global fauna of 4,000 species. Eyes are always absent, and the head is usually lenticular in shape, though it can be elongated and rectangular, as in the Mecistocephalidae. The last pair of legs typically lies along the longitudinal body axis; and the inflated coxae bear variable numbers of pores. Geophilomorphs vary from around 5 to 195 mm (0.2 to 7.8 in.) in length; some are thin and fragile while others are broad and ribbon-like. They occur natively on all the inhabited continents and some species have been introduced to oceanic islands. They range from sea level to high elevations in the Andes and Himalaya Mountains. Several species inhabit littoral zones of sea-shores, a difficult environment to adapt to because of the high salinities.
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All centipedes possess “poison claws” and can inject venom, but most are too small and weak to penetrate human skin. However, large and even moderate-size scolopendromorphs and scutigeromorphs, with their powerful “prehensors,” can inflict painful bites that may necessitate a visit to a doctor and generate intense pain, swelling, discoloration, numbness, and necrosis. However, unlike scorpions and spiders, there are no really dangerous, deadly centipedes, and there are no confirmed human fatalities. I was once bitten on a finger by an inch long individual of Scolopocryptops sexspinosus, and the digit swelled up and throbbed for about an hour, thus being similar to a wasp sting. In the southeastern US, Hemiscolopendra marginata, which can grow to 75 mm (3 in.) in length, frequently enters buildings, and persons accidentally encountering it can be bitten. During World War II, Scolopendra subspinipes, a wandering species, was a scourge to American soldiers fighting in the Pacific. Large individuals roamed freely around military installations, falling into foxholes and entering latrine shelters and tents, where they would crawl into blankets on beds. Many soldiers were bitten and experienced instant, fiery pain; medical staff were frequently called to treat centipede bites, and an ingenious medic conceived of injecting localized dental anesthetic in the vicinities of bites, which afforded quick relief (Remington 1950). Thus, while there are no dangerous, deadly centipedes, the bite of large ones can cause severe pain and discomfort, to the point that persons living in tropical areas should be suitably cautious. Collectors should always pick up even moderate-sized species with forceps, never the hands, and because of their flexibility, specimens should always be grasped behind the head so as to be able to control the biting end of the body. If they are grasped near mid-length or caudally, the animals can bend their bodies 180 degrees and still bite one’s hand or fingers.
Chilopoda comprises 2 subclasses, 5 orders, and 23 families. Eleven
families occur in the US and Canada, but the number of genera and
species is uncertain because the composition of the two most
speciose orders, Lithobiomorpha and Geophilomorpha, is unknown as
they have never been comprehensively investigated. In the
currently accepted classification, subfamilies are provided for
Scolopendromorpha, where I have more taxonomic experience. Taxa
known or thought to occur in North America are in bold and
preceded by asterisks (*); ENT. denotes an endemic
taxon, INT. signifies one that is wholly introduced, and I-N denotes one with both introduced and native species.
Clade 3 (*Schendylidae + (Ballophilidae +
While I produced a second chilopod Nomenclator (Shelley 2006a) to supplement the first by Jeekel (2005), my research on the Chilopoda primarily involves taxonomic and faunal studies in the Scolopendromorpha. The focus is on this order for three reasons: 1) it includes the conspicuous, large-bodied species that are well known to the general public, who understandably seek information on them; 2) the larger scolopendromorphs can deliver a painful bite and hence can hurt humans; and 3) the taxonomic problems with this order are less severe than those with the more diverse orders Lithobiomorpha and Geophilomorpha, where the difficulties greatly complicate and hinder their research. The initial objectives were to elucidate the North American fauna, and early publications included faunistic studies on North Carolina & Florida (Shelley 1987, Shelley & Edwards 1987) and treatments of the subfamily Plutoniuminae (Cryptopidae) (Shelley 1990, 1997). Basic taxonomic research was necessary to clarify and stabilize names (Hoffman & Shelley 1996, Shelley 2000a), which culminated in a faunistic study of the continental fauna (Shelley 2002); this work was published by the Virginia Museum of Natural History and can be ordered through their website at http://www.vmnh.net/centipede.htm. The continental fauna is also summarized, with photos and distribution maps of certain taxa, on the NCSM website at http://www.naturalsciences.org/research/inverts/centipedes/index.html. At the request of colleagues in Hawaii, I have also authored or co-authored works on the centipede fauna of this state, most of which is introduced (Shelley 1991, 2000b; Zapparoli & Shelley 2000; Bonato et al. 2004). The scolopendromorph centipede research has recently expanded beyond North America into the Neotropical region, with one publication on an Australian species (Shelley 2000c, 2006b; Shelley & Heatwole 1996; Shelley & Kiser 2000; Shelley & Mercurio 2005). I also collaborated on a work standardizing scolopendromorph terminology (Lewis et al. 2005) and interacted with 8 other specialises to develop Chilobase, a web-based taxonomic listing of all currently recognized centipede species in the world (http://chilobase.bio.unipd.it/). Two major projects are presently being pursued along with several minor ones:
1. Redescription of the centipede, Ectonocryptops kraepelini Crabill, 1977 (with R. Mercurio)
2. Synoptic review of the New World genus Hemiscolopendra.
Bonato, L., D. Foddai, A. Minelli, & R. M. Shelley. 2004. The centipede order Geophilomorpha in the Hawaiian Islands (Chilopoda). Bishop Museum Occasional Papers, 78:13-32.
Chagas, A., & R. M. Shelley. 2003. The centipede genus Newportia Gervais, 1847, in Mexico: description of a new troglomorphic species; redescription of N. sabina Chamberlin, 1942; revival of N. azteca Humbert & Saussure, 1869; and a summary of the fauna (Scolopendromorpha: Scolopocryptopidae: Newportiinae). Zootaxa, 379:1-20.
_____, _____. 2004. Rediscovery and redescription of the centipede, Paracryptops inexpectus Chamberlin, 1914, with an account of the genus (Scolopendromorpha: Cryptopidae: Cryptopinae). Zootaxa, 475:1-8.
Hoffman, R. L., & R. M. Shelley. 1996. The identity of Scolopendra marginata Say (Chilopoda: Scolopendromorpha: Scolopendridae). Myriapodologica, 4(5):35-42.
Jeekel, C.A.W. 2005. Nomenclator generum et familiarum Chilopodorum: A list of the genus and family-group names in the Class CHILOPODA from the 10th edition of Linnaeus, 1758, to the end of 1957. Myriapod Memoranda Supplement 1:1-130.
Lewis, J.G.E. 1981a. The Biology of Centipedes. Cambridge University Press, Cambridge, UK. 476 pp.
_____. 1981b. Swimming in the centipede Scolopendra subspinipes Leach (Chilopoda, Scolopendromorpha). Entomologist's Monthly Magazine, 116:121-122
_____. 1982. Observations on the morphology and habits of the bizarre Borneo centipede Arrhabdotus octosulcatus (Chilopoda, Scolopendromorpha). Entomologist's Monthly Magazine, 117:245-248.
_____, G.D. Edgecombe, & R.M. Shelley. 2005. A proposed standardised terminology for the external taxonomic characters of the Scolopendromorpha (Chilopoda). Fragmenta Faunistica, 48(1):1-8
_____. A. Minelli, & R.M. Shelley. 2006. Taxonomic and nomenclatural notes on scolopendrid centipedes (Chilopoda: Scolopendromorpha: Scolopendridae). Zootaxa, 1155:35-40
Shelley, R. M. 1987. The scolopendromorph centipedes of North Carolina, with a taxonomic assessment of Scolopocryptops gracilis peregrinator (Crabill) (Chilopoda: Scolopendromorpha). Florida Entomologist, 70:498-512.
_____. 1990. The centipede Theatops posticus (Say) (Scolopendromorpha: Cryptopidae) in the southwestern United States and Mexico. Canadian Journal of Zoology, 68:2637-2644.
_____. 1991. Deletion of the centipede Theatops spinicaudus (Wood) from the Hawaiian fauna (Scolopendromorpha: Cryptopidae). Bishop Museum Occasional Papers, 31:182-184.
_____. 1997. The Holarctic centipede subfamily Plutoniuminae (Chilopoda: Scolopendromorpha: Cryptopidae) (nomen correctum ex subfamily Plutoniinae Bollman, 1893). Brimleyana, 24:51-113.
_____. 2000a. Neotype designation for the centipede Mycotheres leucopoda Rafinesque (Scolopendromorpha: Cryptopidae). Myriapodologica, 7(2):15-17.
_____. 2000b. The centipede order Scolopendromorpha in the Hawaiian Islands (Chilopoda). Bishop Museum Occasional Papers 64:39-48.
_____. 2000c. Occurrence of the centipede, Dinocryptops miersii (Newport) (Scolopendromorpha: Scolopocryptopidae), in Tobago, Trinidad and Tobago. Caribbean Journal of Science, 36(1-2):155-156.
_____. 2002. A synopsis of the North American centipedes of the order Scolopendromorpha (Chilopoda). Virginia Museum of Natural History Memoir No. 5:1-108.
_____. 2004. Occurrences of the centipedes, Scolopendra morsitans L. and S. subspinipes Leach, on Pacific Islands (Chilopoda: Scolopendromorpha: Scolopendridae). Ent. News, 115(2):79-83.
_____. 2006a. Nomenclator generum et familiarum Chilopodorum II: A list of the genus- and family-group names in the Class Chilopoda from 1958 through 2005. Zootaxa, 1198:1-20.
_____. 2006b. A chronological catalog of the New World species of Scolopendra L., 1758 (Chilopoda: Scolopendromorpha: Scolopendridae). Zootaxa, 1253:1-50.
____, & A. Chagas. 2004. The centipede genus Arthrorhabdus Pocock, 1891, in the Western Hemisphere: potential occurrence of A. pygmaeus (Pocock, 1895) in Belize (Scolopendromorpha: Scolopendridae: Scolopendrinae). Western North American Naturalist, 64(4):532-537.
_____, & G. B. Edwards. 1987. The scolopendromorph centipedes of Florida, with an introduction to the common myriapodous arthropods. Florida Department of Agriculture & Consumer Services Entomology Circular No. 300:1-4.
____, ____. 2004. A fourth Floridian record of the centipede genus Rhysida Wood, 1862; potential establishment of R. l. longipes (Newport, 1845) in Miami-Dade County (Scolopendromorpha: Scolopendridae: Otostigminae). Entomological News, 115(2):116-119.
_____, & H. Heatwole. 1996. A second Australian record of the centipede Asanada brevicornis Meinert (Scolopendromorpha). Entomologists Monthly Magazine, 132:280.
_____, & S. B. Kiser. 2000. Neotype designation and a diagnostic account for the centipede, Scolopendra gigantea L. 1758, with an account of S. galapagoensis Bollman 1889 (Chilopoda Scolopendromorpha Scolopendridae). Tropical Zoology, 13:159-170.
_____, & R. Mercurio. 2005. Ectonocryptoides quadrimeropus, a new centipede genus and species from Jalisco, Mexico; proposal of Ectonocryptopinae, analysis of subfamilial relationships, and a key to subfamilies and genera of the Scolopocryptopidae (Scolopendromorpha). Zootaxa, 1094:25-40.
____, G. B. Edwards, & A. Chagas. Introduction of the centipede Scolopendra morsitans L., 1758, into northeastern Florida, the first authentic North American record, with a review of its global occurrences (Scolopendromorpha: Scolopendridae: Scolopendrinae). Entomological News, 116(1): 39-58.Zapparoli, M., & R. M. Shelley. 2000. The centipede order Lithobiomorpha in the Hawaiian Islands (Chilopoda). I. The epigean fauna. Bishop Museum Occasional Papers, 63:35-49.