Editing Lancelet (section)

=== Reproduction and spawning ===
Lancelets are [[Gonochorism|gonochoric]] animals, i.e. having two sexes, and they reproduce via external [[Fertilisation|fertilization]]. They only reproduce during their [[Spawn (biology)|spawning]] season, which varies slightly between species — usually corresponding to spring and summer months.<ref name=":0">{{Cite journal|last=Escriva|first=Hector|date=2018|title=My Favorite Animal, Amphioxus: Unparalleled for Studying Early Vertebrate Evolution| journal= BioEssays| language= en| volume= 40| issue= 12|pages= 1800130| doi= 10.1002/bies.201800130|pmid=30328120|s2cid=53528269|issn=1521-1878| url=https://hal.sorbonne-universite.fr/hal-01974406/file/83-Escriva-2018-BioEssays_sans%20marque.pdf}}</ref> All lancelets species spawn shortly after sunset, either synchronously (e.g. ''Branchiostoma floridae'', about once every two weeks during spawning season<ref name=":2">{{Cite journal |last1= Stokes|first1=M. Dale| last2= Holland|first2=Nicholas D.| date= 1996| title=Reproduction of the Florida Lancelet (Branchiostoma floridae): Spawning Patterns and Fluctuations in Gonad Indexes and Nutritional Reserves| journal=Invertebrate Biology| volume=115|issue=4|pages=349|doi=10.2307/3227024|issn=1077-8306| jstor=3227024|bibcode=1996InvBi.115..349S }}</ref>) or asynchronously (''Branchiostoma lanceolatum'', gradual spawning through the season<ref>{{Cite journal| last1=Fuentes|first1=Michael|last2=Benito|first2=Elia|last3=Bertrand|first3=Stephanie|last4=Paris|first4=Mathilde|last5=Mignardot|first5=Aurelie|last6=Godoy|first6=Laura|last7=Jimenez-Delgado| first7=Senda|last8=Oliveri|first8=Diana|last9=Candiani|first9=Simona|date=2007| display-authors=3| title= Insights into spawning behavior and development of the european amphioxus (Branchiostoma lanceolatum)|journal=Journal of Experimental Zoology Part B: Molecular and Developmental Evolution| language= en| volume= 308B| issue= 4|pages=484–493| doi= 10.1002/jez.b.21179|pmid=17520703|bibcode=2007JEZB..308..484F |issn= 1552-5015}}</ref>).

As stated above, all amphioxus species exhibit gonochorism, with only rare instances of [[Hermaphrodite|hermaphroditism]] reported in ''Branchiostoma lanceolatum '' and ''B. belcheri''. In these cases, a small number of female gonads were observed within male individuals, typically ranging from 2 to 5 gonads out of a total of 45–50. An extraordinary occurrence of complete sex reversal was documented in ''B. belcheri'', where a female amphioxus raised in laboratory conditions underwent a transformation into a male (Zhang et al., 2001).

Nicholas and [[Linda Holland]] were the first researchers to describe a method of obtaining amphioxus embryos by induction of spawning in captivity and in vitro fertilization.<ref>{{Cite journal |title=Fine Structural Study of the Cortical Reaction and Formation of the Egg Coats in a Lancelet|journal = The Biological Bulletin|volume = 176|issue = 2|pages = 111–122| first1= Nicholas D. | last1= Holland | first2= Linda Z. | last2= Holland |doi= 10.2307/1541578| jstor= 1541578|year = 1989|url = https://www.biodiversitylibrary.org/part/10948}}</ref> Spawning can be artificially induced in the lab by electric or thermal shock.<ref>{{Cite journal| author1=Guang Li |author2=ZongHuang Shu |author3=Yiquan Wang|title=Year-Round Reproduction and Induced Spawning of Chinese Amphioxus, Branchiostoma belcheri, in Laboratory|journal=PLOS ONE| volume= 8|issue =9| pages= e75461| doi= 10.1371/journal.pone.0075461| pmid=24086537|pmc=3784433|year=2013|bibcode=2013PLoSO...875461L|doi-access= free}}</ref>