Editing Anaconda (section)

===Sexual dimorphism===
[[Sexual dimorphism|Sexual size dimorphism]] in ''Eunectes'' is the opposite of most other vertebrates. Females are larger than males in most snakes, and green anacondas ''([[Eunectes murinus|E. murinus]])'' have one of the most extreme size differences, where females average roughly {{convert|32|kg|lb|-1|abbr=on}} and males average only around {{convert|7|kg|lb|abbr=on}}.<ref name="Pizzatto" /><ref name="Rivas_etal_2007">{{cite book|last1=Rivas|first1=Jesús A.|last2=Muñoz|first2=M. C.|last3=Burghardt|first3=G. M.|last4=Thorbjarnarson|first4=J. B.|chapter=Sexual size dimorphism and the mating system of the green anaconda (''Eunectes murinus'')|pages=461–473|title=Biology of the Boas and Pythons|year=2007|editor-last1=Henderson|editor-first1=Robert W.|editor-last2=Powell|editor-first2=Robert|location=Eagle Mountain, Utah|publisher=Eagle Mountain Publishing|isbn=978-0-9720154-3-1}}</ref> This size difference has several benefits for both sexes. Large size in females leads to higher [[fecundity]] and larger offspring; as a result male [[mate choice]] favours larger females.<ref name="Rivas2001">{{Cite journal |last1=Rivas |first1=Jesús A. |last2=Burghardt |first2=Gordon M. |date=2001 |title=Understanding sexual size dimorphism in snakes: wearing the snake's shoes |journal=Animal Behaviour |volume=62 |issue=3 |pages=F1–F6 |doi=10.1006/anbe.2001.1755|s2cid=5374924 }}</ref> Large size is also favoured in males because larger males tend to be more successful at reproducing, both because of their size advantage in endurance rivalry and their advantage in [[sperm competition]] because larger males are able to produce more sperm.<ref name="Rivas2001" /> One reason that males are so much smaller in ''Eunectes'' is that large males can be confused for females, which interferes with their ability to mate when smaller males mistakenly coil them in breeding balls; as a result, there is an optimum size for males where they are large enough to successfully compete, but not large enough to risk other males trying to mate with them.<ref name="Rivas2001" />