Editing Amphiuma (section)

== Sexual dimorphism ==
Amphiuma demonstrate [[sexual dimorphism]] in relation to the size of their bodies and the size of their heads.<ref name=":1">{{Cite journal|last1=Fontenot|first1=Clifford L.|last2=Seigel|first2=Richard A.|title=Sexual dimorphism in the three-toed amphiuma, ''Amphiuma tridactylum'': sexual selection or ecological causes |journal=Copeia|language=en-US|volume=2008|issue=1|pages=39–42|doi=10.1643/cg-06-060|year=2008|s2cid=30731154}}</ref> Generally, males have been found to possess larger bodies and longer heads compared to the female sex, which normally is indicative of male-male combat observed within the population.<ref name=":1" /><ref name=":2">{{Cite journal|last=Shine|first=Richard|date=1979|title=Sexual selection and sexual dimorphism in the Amphibia |jstor=1443418|journal=Copeia|volume=1979|issue=2|pages=297–306|doi=10.2307/1443418}}</ref> There has been, however, no other physical indicating factors for male-male combat as in other species of amphibians, such as horns or spines.<ref name=":2" /> Some populations do not show these sexual dimorphic traits, and in certain locations female and male bodies do not exhibit any traits with significant differences.<ref name=":02">{{Cite journal|last=Cagle|first=Fred R.|date=1948|title=Observations on a population of the salamander, ''Amphiuma tridactylum'' Cuvier |jstor=1932640|journal=Ecology|volume=29|issue=4|pages=479–491|doi=10.2307/1932640}}</ref>

Amphiumas may be sexed as male or female based on the pigmentation of the cloacal opening.<ref name=":4">{{Cite journal|last=Fontenot|first=Clifford L.|title=Reproductive Biology of the Aquatic Salamander Amphiuma Tridactylum in Louisiana|journal=Journal of Herpetology|language=en-US|volume=33|issue=1|pages=100–105|doi=10.2307/1565548|year=1999|jstor=1565548}}</ref> Males exhibit white or pink coloration while females exhibit dark pigmentation. Occasionally, males may demonstrate partial pigmentation, but never have full dark coloration like that of females.