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Centipedes grow their legs at different points in their development. In the primitive condition, seen in the Lithobiomorpha, Scutigeromorpha, and Craterostigmomorpha, development is [[Anamorphosis (biology)|anamorphic]]: more segments and pairs of legs are grown between [[ecdysis|moults]].<ref>{{cite journal |last=Fusco |first=Giuseppe |title=Trunk segment numbers and sequential segmentation in myriapods. |journal=Evolution & Development |date=December 2005 |volume=7 |issue=6 |pages=608–617 |doi=10.1111/j.1525-142X.2005.05064.x |pmid=16336414 |s2cid=21401688 |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1525-142X.2005.05064.x |access-date=25 August 2020}}</ref> 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.{{sfn|Lewis|2007|p=27}} The Craterostigmomorpha only have one phase of anamorphosis, with embryos having 12 pairs, and adults 15.<ref name="Edgecombe Giribet 2007"/>
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; the maximum number of [[Thorax (arthropod anatomy)|thoracic]] segments varies within species, often on a geographical basis, and in most cases, females bear more legs than males. The number of leg-bearing segments in these groups varies from
Centipede segments are developed in two phases. Firstly, the head gives rise to a fixed but odd number of segments, driven by [[Hox gene]]s as in all arthropods.<ref name="Held 2014"/><ref name="Hughes Kaufman 2002">{{cite journal |last1=Hughes |first1=Cynthia L. |last2=Kaufman |first2=Thomas C. |title=Exploring the myriapod body plan: expression patterns of the ten Hox genes in a centipede |journal=Development |date=2002 |volume=129 |issue=5 |pages=1225–1238 |doi=10.1242/dev.129.5.1225 |pmid=11874918 |url=https://dev.biologists.org/content/develop/129/5/1225.full.pdf |access-date=2023-05-03 |archive-date=2019-08-23 |archive-url=https://web.archive.org/web/20190823081013/https://dev.biologists.org/content/develop/129/5/1225.full.pdf |url-status=bot: unknown }}</ref> 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 signaling pathway#Segmentation|Notch signalling pathway]]. The segments are [[Homology (biology)|homologous]] with the legs of other arthropods such as [[trilobite]]s; it would be sufficient for the Notch clock [[Heterochrony#Mechanisms|to run faster]], as it does in [[snake]]s, to create more legs.<ref name="Held 2014">{{cite book |last=Held |first=Lewis I. |author-link=Lewis I. Held |chapter=Why the centipede has odd segments |title=How the Snake Lost its Legs. Curious Tales from the Frontier of Evo-Devo |date=2014 |publisher=[[Cambridge University Press]] |isbn=978-1-107-62139-8 |pages=69, 120 |title-link=How the Snake Lost its Legs }}</ref>
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