Centipede Late | |
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Various centipedes (clockwise from top left): Thereuopoda clunifera , a Scutigeromorph; Lithobius forficatus , a Lithobiomorph; Geophilus , a Geophilomorph; and Scolopendra cataracta , a Scolopendromorph | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Myriapoda |
Class: | Chilopoda Latreille, 1817 |
Orders and suborders | |
Centipedes (from Neo-Latin centi- , "hundred", and Latin pes, pedis , "foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek χεῖλος , kheilos, lip, and Neo-Latin suffix -poda , "foot", describing the forcipules) of the subphylum Myriapoda, an arthropod group which includes millipedes and other multi-legged animals. Centipedes are elongated segmented (metameric) creatures with one pair of legs per body segment. All centipedes are venomous and can inflict painful stings, injecting their venom through pincer-like appendages known as forcipules or toxicognaths, which are actually modified legs instead of fangs. Despite the name, no centipede has exactly 100 pairs of legs; the number of pairs of legs is an odd number that ranges from 15 pairs to 191 pairs. [1]
Centipedes are predominantly generalist carnivorous, hunting for a variety of prey items that can be overpowered. They have a wide geographical range, which can be found in terrestrial habitats from tropical rainforests to deserts. Within these habitats, centipedes require a moist microhabitat because they lack the waxy cuticle of insects and arachnids, therefore causing them to rapidly lose water. Accordingly, they avoid direct sunlight by staying under cover or by being active at night.
Centipedes have a rounded or flattened head, bearing a pair of antennae at the forward margin. They have a pair of elongated mandibles, and two pairs of maxillae. The first pair of maxillae form the lower lip, and bear short palps. The first pair of limbs stretch forward from the body over the mouth. These limbs, or forcipules, end in sharp claws and include venom glands that help the animal to kill or paralyze its prey. [2] Their size ranges from a few millimetres in the smaller lithobiomorphs and geophilomorphs to about 30 cm (12 in) in the largest scolopendromorphs. [3]
Many species of centipedes lack eyes, but some possess a variable number of ocelli, sometimes clustered together to form true compound eyes. However, these eyes are only capable of discerning light from dark, and provide no true vision. In some species, the first pair of legs can function as sensory organs, similar to antennae; unlike the antennae of most other invertebrates, these point backwards. An unusual clustering of sensory organs found in some centipedes is the organ of Tömösváry. The organs, at the base of the antennae, consist of a disc-like structure and a central pore, with an encircling of sensitive cells. They are likely used for sensing vibrations, and may provide a weak form of hearing. [2]
Forcipules are unique to centipedes. The forcipules are modifications of the first pair of legs (the maxillipeds), forming a pincer-like appendage, just behind the head. Forcipules are not oral mouthparts, though they are used to subdue prey by injecting venom and gripping the prey animal. Venom glands run through a tube, from inside the head to the tip of each forcipule. [4]
Behind the head, the body consists of at least fifteen segments. Most of the segments bear a single pair of legs; the maxillipeds project forward from the first body segment, while the final two segments are small and legless. Each pair of legs is slightly longer than the pair preceding them, ensuring that they do not overlap, which reduces the chance that they will collide and trip the animal. The last pair of legs may be as much as twice the length of the first pair. The final segment bears a telson, and includes the openings of the reproductive organs. [2]
Centipedes mainly use their antennae to seek out their prey. The digestive tract forms a simple tube, with digestive glands attached to the mouthparts. Like insects, centipedes breathe through a tracheal system, typically with a single opening, or spiracle, on each body segment. They excrete waste through a single pair of malpighian tubules. [2]
Just as the first pair of legs are modified into forcipules, the back legs are modified into "ultimate legs", also called anal legs, caudal legs, and terminal legs. [5] Their use varies between species, but does not include locomotion. [6] [7] The ultimate legs may be elongated and thin, thickened, or pincer-like. [7] They are frequently sexually dimorphic, and may play a role in mating rituals. [6] [7] Because glandular pores occur more frequently on ultimate legs than on the "walking" legs, they may serve a sensory role. [6] [7] They are sometimes used in defensive postures, and some species use them to capture prey, defend themselves against predators, or suspend themselves from objects such as branches, using the legs as pincers. [6] Several species use their ultimate legs upon encountering another centipede, trying to grab the body of the other centipede. [8]
Members of the genus Alipes can stridulate their leaf-like ultimate legs to distract or threaten predators. [8] Rhysida immarginata togoensis makes a faint creaking sound when it swings its ultimate legs. [8]
Scholars have noted that disinformation exists about the difference between millipedes and centipedes, and they seek to provide more generalized information for education purposes. [9] Both groups of myriapods have long, multi-segmented bodies, many legs, a single pair of antennae, and the presence of postantennal organs. Centipedes have one pair of legs per segment, while millipedes have two. Their heads differ in that millipedes have short, elbowed antennae, a pair of robust mandibles and a single pair of maxillae fused into a lip; centipedes have long, threadlike antennae, a pair of small mandibles, two pairs of maxillae and a pair of large venom claws. [10]
Trait | Millipedes | Centipedes |
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Legs | Two pairs on most body segments; attached to underside of body | One pair per body segment; attached to sides of body; last pair extends backwards |
Locomotion | Generally adapted for burrowing or inhabiting small crevices; slow-moving | Generally adapted for running, except for the burrowing soil centipedes |
Feeding | Primarily detritivores, some herbivores, few carnivores; no venom | Primarily carnivores with front legs modified into venomous fangs |
Spiracles | On underside of body | On the sides or top of body |
Reproductive openings | Third body segment | Last body segment |
Reproductive behaviour | Male generally inserts spermatophore into female, using his gonopods | Male produces spermatophore that is usually picked up by female |
Centipede reproduction does not involve copulation. Males deposit a spermatophore for the female to take up. In temperate areas, egg laying occurs in spring and summer. A few parthenogenetic species are known. [11] Females provide parental care, both by curling their bodies around eggs and young, and by grooming them, probably to remove fungi and bacteria. [12]
Centipedes are longer-lived than insects; the European Lithobius forficatus may live for 5 to 6 years, [13] and the wide-ranging Scolopendra subspinipes can live for over 10 years. [14] The combination of a small number of eggs laid, long gestation period, and long time of development to reproduction has led authors to label lithobiomorph centipedes as K-selected. [15]
Centipedes grow their legs at different points in their development. In the primitive condition, seen in the orders Lithobiomorpha, Scutigeromorpha, and Craterostigmomorpha, development is anamorphic: more segments and pairs of legs are grown between moults. [16] For example, Scutigera coleoptrata , the house centipede, hatches with only four pairs of legs and in successive moults has 5, 7, 9, 11, 15, 15, 15 and 15 pairs respectively, before becoming a sexually mature adult. Life stages with fewer than 15 pairs of legs are called larval stadia (there are about five stages). After the full complement of legs is achieved, the now postlarval stadia (about five more stages) develop gonopods, sensory pores, more antennal segments, and more ocelli. All mature lithobiomorph centipedes have 15 leg-bearing segments. [17] The Craterostigmomorpha only have one phase of anamorphosis, with embryos having 12 pairs, and adults 15. [1]
The clade Epimorpha, consisting of the orders Geophilomorpha and Scolopendromorpha, is epimorphic, meaning that all pairs of legs are developed in the embryonic stages, and offspring do not develop more legs between moults. This clade contains the longest centipedes. In the Geophilomorpha, the number of thoracic segments usually varies within species, often on a geographical basis, and in most cases, females bear more legs than males. The number of leg-bearing segments varies within each order (usually 21 or 23 in the Scolopendromorpha; from 27 to 191 in the Geophilomorpha), [18] but the total number of pairs is always odd, so there are never exactly 100 legs or 100 pairs, despite the group's common name. [1] [19] [20] [21]
Centipede segments are developed in two phases. Firstly, the head gives rise to a fixed but odd number of segments, driven by Hox genes as in all arthropods. [22] [23] Secondly, pairs of segments are added at the tail (posterior) end by the creation of a prepattern unit, a double segment, which is then always divided into two. The repeated creation of these prepattern units is driven by an oscillator clock, implemented with the Notch signalling pathway. The segments are homologous with the legs of other arthropods such as trilobites; it would be sufficient for the Notch clock to run faster, as it does in snakes, to create more legs. [22]
Centipedes are predominantly generalist predators, which means they are adapted to eat a broad range of prey. [24] Common prey items include lumbricid earthworms, dipteran fly larvae, collembolans, and other centipedes. [25] They are carnivorous; study of gut contents suggests that plant material is an unimportant part of their diets, although they eat vegetable matter when starved during laboratory experiments. [24]
Species of Scolopendromorph, noticeably members from the genera Scolopendra and Ethmostigmus , are able to hunt for substantial prey items, including large invertebrates and sizable vertebrates, which could be larger than the myriapod itself. [26] [27] For instance, Scolopendra gigantea (the Amazonian giant centipede) preys on tarantulas, scorpions, lizards, frogs, birds, mice, snakes, and even bats, catching them in midflight. [28] Three species ( Scolopendra cataracta , S. paradoxa , and S. alcyona ) are amphibious, believed to hunt aquatic or amphibious invertebrates. [29] [30]
Many larger animals prey upon centipedes, such as mongooses, mice, salamanders, beetles and some specialist snake species. [31] They form an important item of diet for many species and the staple diet of some such as the African ant Amblyopone pluto , which feeds solely on geophilomorph centipedes, [32] and the South African Cape black-headed snake Aparallactus capensis . [31]
Some Geophilomorph, Lithobiomorph, and Scolopendromorph centipedes produce sticky, toxic secretions to defend themselves. The various secretions ward off or entangle predators. [33] [34] Scolopendromorph secretions contain hydrogen cyanide. [35] Among Geophilomorphs, the secretions of Geophilus vittatus are sticky and odorous, and contain hydrogen cyanide. [36]
The giant desert centipede of Arizona, Scolopendra polymorpha , has a black head and tail, and an orange body; this conspicuous pattern may be aposematic, an honest signal of the animal's toxicity. [12] Many species raise and splay their ultimate legs and display the spines found on the legs in a defensive threat posture. [8]
Because centipedes lack the waxy water-resistant cuticle of other arthropods, they are more susceptible to water loss via evaporation. [37] Thus, centipedes are most commonly found in high-humidity environments to avoid dehydration, [38] and are mostly nocturnal. [39]
Centipedes live in many different habitats including in soil and leaf litter; they are found in environments as varied as tropical rain forests, [25] deserts, [40] and caves. [41] Some geophilomorphs are adapted to littoral habitats, where they feed on barnacles. [42]
As of the 2019 IUCN Red List, there are two vulnerable and one endangered species of centipede: the Serpent Island centipede (Scolopendra abnormis), Turk's earth centipede (Nothogeophilus turki), and the Seychelles long-legged centipede (Seychellonema gerlachi), the first two of which are vulnerable and the last endangered. [43] [44] [45]
The fossil record of centipedes extends back to 430 million years ago, during the Late Silurian ( Crussolum ), [46] [47] though they are rare throughout the Paleozoic. [48] Devonian Panther Mountain Formation contains two species of centipede, one is species of scutigeromorph Crussolum, other one is Devonobius which is included in an extinct group Devonobiomorpha. [49] [50] Another Devonian site, Rhynie chert also have record of Crussolum, [49] and possible scutigeromorph head material Rhyniognatha is known, which was once considered as the oldest insect. [51] Three species, one scutigeromorph ( Latzelia ) and two scolopendromorphs ( Mazoscolopendra and poorly known Palenarthrus ), have been described from the Mazon Creek fossil beds, which are Carboniferous, 309–307 mya. [52] More species appear in the Mesozoic, including scolopendromorphs and scutigeromorphs in the Cretaceous. [48] [53]
The following cladogram shows the position of the Chilopoda within the arthropods as of 2019: [54] [55]
Arthropoda |
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Within the myriapods, centipedes are believed to be the first of the extant classes to branch from the last common ancestor. The five orders of centipedes are: Craterostigmomorpha, Geophilomorpha, Lithobiomorpha, Scolopendromorpha, and Scutigeromorpha. These orders are united into the clade Chilopoda by the following synapomorphies: [56]
The Chilopoda are then split into two clades: the Notostigmophora including the Scutigeromorpha and the Pleurostigmophora including the other four orders. The following physical and developmental traits can be used to separate members of the Pleurostigmomorpha from Notostigmomorpha: [57] [58]
It was previously believed that Chilopoda was split into Anamorpha (Lithobiomorpha and Scutigeromorpha) and Epimorpha (Geophilomorpha and Scolopendromorpha), based on developmental modes, with the relationship of the Craterostigmomorpha being uncertain. Recent phylogenetic analyses using combined molecular and morphological characters supports the previous phylogeny. The Epimorpha still exist as a monophyletic group within the Pleurostigmophora, but the Anamorpha are paraphyletic, as shown in the cladogram: [56]
All centipedes are venomous. Over the first 50 million years of the clade's evolutionary history, centipede venoms appear to have consisted of a simple cocktail of about four different components, and differentiation into specific venom types appears to have only occurred after the currently recognized five orders had developed. The evolution of the venom includes horizontal gene transfer, involving bacteria, fungi and oomycetes. [59]
As a food item, certain large centipedes are consumed in China, usually skewered and grilled or deep fried. They are often seen in street vendors’ stalls in large cities, including Donghuamen and Wangfujing markets in Beijing. [60] [61]
Large centipedes are steeped in alcohol to make centipede vodka. [62]
Some species of centipedes can be hazardous to humans because of their bite. While a bite to an adult human is usually very painful and may cause severe swelling, chills, fever, and weakness, it is unlikely to be fatal. Bites can be dangerous to small children and those with allergies to bee stings. The venomous bite of larger centipedes can induce anaphylactic shock in such people. Smaller centipedes are generally incapable of piercing human skin. [63]
Even small centipedes that cannot pierce human skin are considered frightening by some humans due to their dozens of legs moving at the same time and their tendency to dart swiftly out of the darkness towards one's feet. [64] A 19th-century Tibetan poet warned his fellow Buddhists, "if you enjoy frightening others, you will be reborn as a centipede." [65]
Scutigera coleoptrata, also known as the house centipede, is a species of centipede that is typically yellowish-grey and has up to 15 pairs of long legs. Originating in the Mediterranean region, it has spread to other parts of the world, where it can live in human homes. It is an insectivore; it kills and eats other arthropods, such as insects and arachnids.
Myriapods are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial.
The Chinese red-headed centipede, also known as the Chinese red head, is a centipede from East Asia. It averages 20 cm (8 in) in length and lives in damp environments.
Scolopendra subspinipes is a species of very large centipede found throughout southeastern Asia. One of the most widespread and common species in the genus Scolopendra, it is also found on virtually all land areas around and within the Indian Ocean, all of tropical and subtropical Asia from Russia to the islands of Malaysia and Indonesia, Australia, South and Central America, the Caribbean islands, and possibly parts of the southern United States, but how much of this range is natural and how much due to human introduction is unclear. With a wide geographic range and numerous color variations, the species is known by many common names, including jungle centipede, orange-legged centipede, Hawaiian centipede, and Vietnamese centipede.
Scolopendridae is a family of large centipedes.
The Geophilomorpha, commonly known as soil centipedes, are epimorphic and bear upwards of 27 leg-bearing segments. They are eyeless and blind, and bear spiracles on all leg-bearing segments—in contrast to other groups, which usually bear them only on their 3rd, 5th, 8th, 10th, 12th, and 14th segments—a "mid-body break", accompanied by a change in tagmatic shape, occurring roughly at the interchange from odd to even segments. This group is the most diverse centipede order, with 230 genera. Centipedes in this order each have an odd number of leg-bearing segments ranging from 27 to 191. They also have 14–segmented antennae. This order is a monophyletic group including two suborders: the monophyletic Placodesmata, which contains Mecistocephalidae, and Adesmata, which includes the superfamilies Himantarioidea and Geophiloidea. Segment number is usually fixed by species in the family Mecistocephalidae, unlike the case in other families in this order, in which the segment number usually varies within each species. The name "Geophilomorpha" is from Ancient Greek roots meaning "formed to love the earth."
The Scolopendromorpha, also known as tropical centipedes and bark centipedes, are an order of centipedes whose members are epimorphic and usually possess 21 or 23 trunk segments with the same number of paired legs. The number of leg pairs is fixed at 21 for most species in this order and fixed at 23 for the remaining species, except for two species with intraspecific variation: Scolopendropsis bahiensis, which has 21 or 23 leg pairs, and Scolopendropsis duplicata, which has 39 or 43 leg pairs. Species in this order have antennae with 17 or more segments. The order comprises the five families Cryptopidae, Scolopendridae, Mimopidae, Scolopocryptopidae, and Plutoniumidae. Nearly all species in the family Scolopendridae have four ocelli on each side of the head, and the genus Mimops features a pale area often considered an ocellus on each side of the head, whereas the other three families are blind. Species in the family Scolopocryptopidae have 23 leg-bearing segments, whereas species in all other families in this order have only 21 leg-bearing segments. The only 3 known amphibious centipedes, Scolopendra cataracta, Scolopendra paradoxa and Scolopendra alcyona belong to this order.
Scutigeromorpha is an order of centipedes also known as house centipedes. These centipedes are found in the temperate and tropical parts of every continent except Antarctica, with their distribution significantly expanded by the introduction of the Mediterranean species Scutigera coleoptrata throughout Europe, Asia, and North America. The common species S. coleoptrata is a typical representative of this order, lying in wait for other arthropods, then seizing prey using great speed, and all species in this order reflect adaptations for this mode of life.
The Craterostigmomorpha are the least diverse centipede clade, comprising only two extant species, both in the genus Craterostigmus. Their geographic range is restricted to Tasmania and New Zealand. There is a single ocellus on each side of the head capsule. They have a distinct body plan; their anamorphosis comprises a single stage: in their first moult, they grow from having 12 trunk segments to having 15. Adult centipedes in this order, like those in Scutigeromorpha and Lithobiomorpha, have 15 leg-bearing segments. Their low diversity and intermediate position between the primitive anamorphic centipedes and the derived Epimorpha has led to them being likened to the platypus. They represent the survivors of a once diverse clade. Maternal brooding unites the Craterostigmomorpha with the Epimorpha into the clade Phylactometria which includes Craterostigmomorpha, Scolopendromorpha, and Geophilomorpha. This trait is thought to be closely linked with the presence of sternal pores, which secrete sticky or noxious secretions, which mainly serve to repel predators and parasites. The presence of these pores on the Devonian Devonobius which is included in own order Devonobiomorpha permits its inclusion in this clade, allowing its divergence of Lithobiomorpha from Phylactometria to be dated to 375 million years ago.
Scolopendra morsitans, also known as the Tanzanian blue ringleg or red-headed centipede, is a species of centipede in the family Scolopendridae. S. morsitans is the type species for the genus Scolopendra.
Geophilus flavus is a terrestrial, soil-dwelling, species of centipede in the Geophilidae family. G. flavus occurs in a range of habitats across central Europe, North America, Australia and other tropical regions. Geophilomorph centipedes, like centipedes generally, are primary predators, hunting predominantly in underground soil burrows or above ground leaf litter. Their consumption behaviours are influenced by environment and seasonal factors. Given their lack of economic value and marginal medical significance, G.flavus remains largely understudied in mainstream research. Some recent studies have detailed the evolutionary development of G.flavus and Geophilidae generally, illustrating developed predatory features like forcipule venom glands.
The Geophilidae are a polyphyletic, cosmopolitan family of soil centipedes in the superfamily Geophiloidea containing the mostly defunct clades Aphilodontidae, Dignathodontidae, Linotaeniidae, Chilenophilinae, and Macronicophilidae. These centipedes are found almost worldwide.
Himantariidae is a monophyletic family of centipedes in the order Geophilomorpha and superfamily Himantarioidea, found almost exclusively in the Northern Hemisphere. Centipedes in this family feature a short head with a concave labral margin bearing a row of denticles, a single dentate lamella and some pectinate lamellae on each mandible, second maxillae with strongly tapering telopodites and slightly spatulate claws, and a stout forcipular segment with short forcipules and a wide tergite; the ultimate legs usually have no pretarsus, and the female gonopods are distinct and biarticulate.
Oryidae is a monophyletic family of soil centipedes belonging to the superfamily Himantarioidea.
Mecistocephalidae is a monophyletic family of centipedes in the order Geophilomorpha. It is the only family in the suborder Placodesmata. Most species in this family live in tropical or subtropical regions, but some occur in temperate regions. This family is the third most diverse in the order Geophiliomorpha, with about 170 species, including about 130 species in the genus Mecistocephalus.
Schendylidae is a family of centipedes in the order Geophilomorpha found in the Americas, the Palearctic region, Africa, Madagascar, Australia, and southeast Asia, and also on some Pacific islands.
Geophilus persephones is a species of soil centipede in the family Geophilidae discovered in 1999. This species is named after Persephone, the queen of the underworld in Greek mythology, and found in caves in the Gouffre de la Pierre Saint-Martin. It has elongated antennae and legs as well as abundant sensory setae, and like other geophilomorhps it lacks sight, has a flattened trunk, and is well adapted to underground life. This species was the first troglomorphic geophilomorph ever discovered and one of the only two in existence along with Geophilus hadesi. Known from a single male specimen measuring 16.2 mm in length, this species has only 29 pairs of legs, one of only two species in the Geophilidae family to have so few leg pairs.
Dignathodontidae is a monophyletic clade of soil centipedes in the family Geophilidae found in the Mediterranean region, extending to Macaronesia, Caucasus, and western and central Europe. The clade is characterized by a gradually anteriorly tapered body, a short head with non-attenuated antennae, and a poorly sclerotized labrum with tubercles. The number of legs in this clade varies within as well as among species and ranges from 43 pairs to 153 pairs of legs. Species in this clade tend to have more leg-bearing segments and greater intraspecific variability in this number than generally found in the family Geophilidae.
Ultimate legs are a pair of modified rear legs unique to centipedes. Although they do not aid in locomotion, ultimate legs are used for a variety of uses, and their morphology varies accordingly.
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: CS1 maint: numeric names: authors list (link)In 1902, C.L. Marlatt, an entomologist with the United States Department of Agriculture writes in Circular #48 - The House Centipede: It may often be seen darting across floors with great speed, occasionally stopping suddenly and remaining absolutely motionless, presently to resume its rapid movements, often darting directly at residents, particularly women, evidently with a desire to conceal itself beneath their dresses, creating much consternation.