Editing Arachnid (section)

==Reproduction==
{{see also|Spider#Reproduction and life cycle|Scorpion#Reproduction}}
[[File:Vinegaroons in courtship (Thelyphonus sp) (8390306848).jpg|thumb|Courtship behavior of ''[[Thelyphonus]]'' sp.|280px]]
Arachnids may have one or two [[gonad]]s, which are located in the abdomen. The genital opening is usually located on the underside of the second abdominal segment. In most species, the male transfers sperm to the female in a package, or [[spermatophore]]. The males in harvestmen and some mites have a penis.<ref>{{cite journal | pmc=6225839 | year=2018 | last1=McLean | first1=C. J. | last2=Garwood | first2=R. J. | last3=Brassey | first3=C. A. | title=Sexual dimorphism in the Arachnid orders | journal=PeerJ | volume=6 | pages=e5751 | doi=10.7717/peerj.5751 | pmid=30416880 | doi-access=free }}</ref> Complex courtship rituals have evolved in many arachnids to ensure the safe delivery of the sperm to the female.<ref name=IZ/> Members of many orders exhibit sexual dimorphism.<ref name="McLeanGarwood2018">{{cite journal|last1=McLean|first1=Callum J.|last2=Garwood|first2=Russell J.|last3=Brassey|first3=Charlotte A.|title=Sexual dimorphism in the Arachnid orders|journal=PeerJ|volume=6|year=2018|pages=e5751|issn=2167-8359|doi=10.7717/peerj.5751|pmid=30416880|pmc=6225839|doi-access=free}}</ref>

Arachnids usually lay yolky [[egg (biology)|eggs]], which hatch into immatures that resemble adults. Scorpions, however, are either [[ovoviviparous]] or [[viviparous]], depending on species, and bear live young. Also some mites are ovoviviparous and viviparous, even if most lay eggs.<ref>{{Cite book |last=Auerbach |first=Paul S. |url=https://books.google.com/books?id=tdTInPqMCjMC&dq=%2522some+are+ovoviviparous%252C+and+a+few+are+viviparous%2522&pg=PA950 |title=Wilderness Medicine E-Book: Expert Consult Premium Edition - Enhanced Online Features |date=2011-10-31 |publisher=Elsevier Health Sciences |isbn=978-1-4557-3356-9 |language=en}}</ref> In most arachnids only the females provide parental care, with harvestmen being one of the few exceptions.<ref>{{cite journal |last1=Quesada-Hidalgo |first1=Rosannette |last2=Solano-Brenes |first2=Diego |last3=Requena |first3=Gustavo S. |last4=Machado |first4=Glauco |title=The good fathers: efficiency of male care and the protective role of foster parents in a Neotropical arachnid |journal=Animal Behaviour |date=April 2019 |volume=150 |pages=147–155 |doi=10.1016/j.anbehav.2019.02.007|s2cid=73728615 }}</ref><ref>{{cite journal |last1=Nazareth |first1=Tais M. |last2=Machado |first2=Glauco |title=Mating system and exclusive postzygotic paternal care in a Neotropical harvestman (Arachnida: Opiliones) |journal=Animal Behaviour |date=March 2010 |volume=79 |issue=3 |pages=547–554 |doi=10.1016/j.anbehav.2009.11.026|s2cid=53166528 }}</ref>