Editing Cnidaria (section)

===Polymorphism===
[[Polymorphism (biology)|Polymorphism]] refers to the occurrence of structurally and functionally more than two different types of individuals within the same organism. It is a characteristic feature of cnidarians, particularly the [[polyp (zoology)|polyp]] and [[medusae|medusa]] forms, or of [[zooids]] within colonial organisms like those in [[Hydrozoa]].<ref>{{cite journal |doi=10.1098/rspb.1966.0037 |title=Genetic polymorphism |journal=Proceedings of the Royal Society of London. Series B. Biological Sciences |date=1966 |volume=164 |issue=995 |pages=350–361 |pmid=4379524 |bibcode=1966RSPSB.164..350F |last1=Ford |first1=E. B. }}</ref> In [[Hydrozoa]]ns, colonial individuals arising from individual zooids will take on separate tasks.<ref>{{cite journal|last=Dunn|first=Casey W.|author2=Wagner, Günter P.|title=The evolution of colony-level development in the Siphonophora (Cnidaria:Hydrozoa)|journal=Development Genes and Evolution|date=16 September 2006|volume=216|issue=12|pages=743–754|doi=10.1007/s00427-006-0101-8|pmid=16983540|s2cid=278540}}</ref> For example, in ''[[Obelia]]'' there are feeding individuals, the [[gastrozooid]]s; the individuals capable of asexual reproduction only, the gonozooids, blastostyles and free-living or sexually reproducing individuals, the [[medusae]].