Editing Centipede (section)

== Description ==

Centipedes have a rounded or flattened head, bearing a pair of [[antenna (biology)|antennae]] at the forward margin. They have a pair of elongated [[mandible (arthropod)|mandibles]], and two pairs of [[maxilla (arthropod)|maxillae]]. The first pair of maxillae form the lower lip, and bear short [[palp]]s. 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.<ref name="IZ">{{cite book |last=Barnes |first=Robert D. |year=1982 |title=Invertebrate Zoology |publisher=Holt-Saunders International |location=Philadelphia, Pennsylvania |pages=810–816 |isbn=978-0-03-056747-6}}</ref>

Their size ranges from a few millimetres in the smaller [[Lithobiomorpha|lithobiomorphs]] and [[Geophilomorpha|geophilomorphs]] to about {{convert|30|cm|abbr=on}} in the largest [[Scolopendromorpha|scolopendromorphs]].<ref name="Minelli Golovatch 2017">{{cite book |last1=Minelli |first1=A. |last2=Golovatch |first2=S. I. |title=Reference Module in Life Sciences |chapter=Myriapods |publisher=Elsevier |year=2017 |doi=10.1016/b978-0-12-809633-8.02259-7|isbn=978-0-12-809633-8 }}</ref>

=== Sensory organs ===

Many species of centipedes lack eyes, some lack one only, but some possess a variable number of [[ocelli]], sometimes clustered together to form true [[compound eye]]s. 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.<ref name="IZ"/>

=== Forcipules ===
{{main|Forcipule}}

[[File:Eupolybothrus_cavernicolus_forcipules.jpg|thumb|The [[forcipule]]s of ''[[Eupolybothrus cavernicolus]]'' ([[Lithobiidae]])]]

Forcipules are unique to centipedes. The forcipules are modifications of the first pair of [[arthropod leg|legs]] (the maxillipeds), forming a [[pincer (biology)|pincer]]-like [[appendage]], just behind the head. Forcipules are not oral [[Arthropod mouthparts|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.<ref name="Dugon Black Wallace 2012">{{Cite journal |last1=Dugon |first1=Michel M. |last2=Black |first2=Alexander |last3=Arthur |first3=Wallace |date=2012-05-01 |title=Variation and specialisation of the forcipular apparatus of centipedes (Arthropoda: Chilopoda): A comparative morphometric and microscopic investigation of an evolutionary novelty |url=https://www.sciencedirect.com/science/article/pii/S1467803912000151 |journal=Arthropod Structure & Development |volume=41 |issue=3 |pages=231–243 |doi=10.1016/j.asd.2012.02.001 |pmid=22370199 |bibcode=2012ArtSD..41..231D |issn=1467-8039|url-access=subscription }}</ref>

=== Body ===

Behind the head, the body consists of at least fifteen segments. Most of the segments bear a single pair of legs; the [[wikt:maxilliped|maxilliped]]s 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.<ref name=IZ/>

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 [[invertebrate trachea|tracheal system]], typically with a single opening, or [[Spiracle (arthropods)|spiracle]], on each body segment. They excrete waste through a single pair of [[malpighian tubule]]s.<ref name=IZ/>

=== Ultimate legs ===
{{main|Ultimate legs}}

[[File:Centipede_ultimate_legs_collage.jpg|thumb|A collage showing the ultimate legs of various centipedes. From top left, proceeding clockwise: ''[[Rhysida]]'' spp., ''[[Scolopocryptops]] trogloclaudatus, [[Scolopendra dehaani]], [[Lithobius proximus]], [[Lithobius forficatus]], [[Scolopendra cingulata]].'']]

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.<ref>{{Cite journal |last1=Bonato |first1=Lucio |last2=Edgecombe |first2=Gregory |last3=Lewis |first3=John |last4=Minelli |first4=Alessandro |last5=Pereira |first5=Luis |last6=Shelley |first6=Rowland |last7=Zapparoli |first7=Marzio |date=2010-11-18 |title=A common terminology for the external anatomy of centipedes (Chilopoda) |journal=ZooKeys |issue=69 |pages=17–51 |doi=10.3897/zookeys.69.737 |issn=1313-2970 |pmc=3088443 |pmid=21594038|doi-access=free |bibcode=2010ZooK...69...17B }}</ref> Their use varies between species, but does not include locomotion.<ref name=":0">{{Cite journal |last1=Kenning |first1=Matthes |last2=Müller |first2=Carsten H. G. |last3=Sombke |first3=Andy |date=2017-11-14 |title=The ultimate legs of Chilopoda (Myriapoda): a review on their morphological disparity and functional variability |journal=PeerJ |volume=5 |pages=e4023 |doi=10.7717/peerj.4023 |pmid=29158971 |pmc=5691793 |issn=2167-8359 |doi-access=free }}</ref><ref name=":1">{{Cite journal |last1=Kenning |first1=Matthes |last2=Schendel |first2=Vanessa |last3=Müller |first3=Carsten H. G. |last4=Sombke |first4=Andy |date=2019 |title=Comparative morphology of ultimate and walking legs in the centipede Lithobius forficatus (Myriapoda) with functional implications |journal=Zoological Letters |volume=5 |pages=3 |doi=10.1186/s40851-018-0115-x |issn=2056-306X |pmc=6330759 |pmid=30656061 |doi-access=free }}</ref> The ultimate legs may be elongated and thin, thickened, or pincer-like.<ref name=":1"/> They are frequently [[Sexual dimorphism|sexually dimorphic]], and may play a role in mating rituals.<ref name=":0"/><ref name=":1"/> Because glandular pores occur more frequently on ultimate legs than on the "walking" legs, they may serve a sensory role.<ref name=":0"/><ref name=":1"/> 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.<ref name=":0"/> Several species use their ultimate legs upon encountering another centipede, trying to grab the body of the other centipede.<ref name=":2"/>

Members of the genus ''[[Alipes (centipede)|Alipes]]'' can [[stridulate]] their leaf-like ultimate legs to distract or threaten predators.<ref name=":2">{{Cite journal |last1=Kronmüller |first1=Christian |last2=Lewis |first2=John G. J. |date=2015-06-30 |title=On the function of the ultimate legs of some Scolopendridae (Chilopoda, Scolopendromorpha) |journal=ZooKeys |issue=510 |pages=269–278 |doi=10.3897/zookeys.510.8674 |issn=1313-2970 |pmc=4523778 |pmid=26257548|doi-access=free |bibcode=2015ZooK..510..269K }}</ref> ''[[Rhysida immarginata|Rhysida immarginata togoensis]]'' makes a faint creaking sound when it swings its ultimate legs.<ref name=":2"/>

=== Distinction from millipedes ===

There are many differences between millipedes and centipedes.<ref name="Shelley 1999">{{cite journal |last=Shelley |first=Rowland M. |title=Centipedes and millipedes with emphasis on North American fauna |journal=The Kansas School Naturalist |year=1999 |volume=45 |issue=3 |pages=1–16 |url=http://www.emporia.edu/ksn/v45n3-march1999/ |access-date=2013-10-14 |archive-url=https://web.archive.org/web/20161112025334/http://www.emporia.edu/ksn/v45n3-march1999/ |archive-date=2016-11-12 |url-status=dead }}</ref> Both groups of myriapods have long, multi-segmented bodies, many legs, a single pair of antennae, and the presence of [[Tömösváry organ|postantennal organ]]s. Centipedes have one pair of legs per segment, while millipedes have two. Their heads differ in that millipedes have short, elbowed [[Antenna (biology)|antenna]]e, 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.<ref name=Blower>{{cite book|author=Blower, John Gordon |title=Millipedes: Keys and Notes for the Identification of the Species |url=https://books.google.com/books?id=VQsVAAAAIAAJ&pg=PA1 |year=1985 |publisher=Brill Archive |isbn=978-90-04-07698-3 |page=1}}</ref>

[[File:Millipede centipede side-by-side.png|thumb|upright|alt=Millipede and centipede|A representative millipede and centipede (not necessarily to scale)]]

{|class="wikitable"
|+ Millipede versus centipede differences<ref name="Shelley 1999"/>
! Trait
! [[Millipede]]s
! Centipedes
|- 
! 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 [[Geophilomorpha|soil centipedes]]
|- 
! Feeding
|Primarily [[detritivore]]s, some [[herbivore]]s, few [[carnivore]]s; 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 [[gonopod]]s
|Male produces spermatophore that is usually picked up by female
|}