Editing Orb-weaver spider (section)

=== Sexual size dimorphism ===
[[Sexual dimorphism]] refers to physical differences between males and females of the same species. One such difference can be in size.

Araneids often exhibit size dimorphism typically known as extreme sexual size dimorphism, due to the extent of differences in size. The size difference among species of Araneidae ranges greatly. Some females, such as those of the ''[[Nephila pilipes]]'', can be at least 9 times larger than the male, while others are only slightly larger than the male.<ref name=GustSchaCodd00/> The larger size female is typically thought to be selected through [[fecundity selection]],<ref name=LegrMors00/> the idea that bigger females can produce more eggs, thus more offspring. Although a great deal of evidence points towards the greatest selection pressure on larger female size, some evidence indicates that selection can favor small male size, as well.

Araneids also exhibit a phenomenon called [[sexual cannibalism]], which is commonly found throughout the Araneidae.<ref name="Elga91" /> Evidence suggests a negative correlation between sexual size dimorphism and instances of sexual cannibalism.<ref name="LegrMors00" /> Other evidence, however, has shown that differences in cannibalistic events among araneids when having smaller or slightly larger males is advantageous.<ref name=Elga91/>

Some evidence has shown that extreme dimorphism may be the result of males avoiding detection by the females. For males of these species, being smaller in size may be advantageous in moving to the central hub of a web so female spiders may be less likely to detect the male, or even if detected as prey to be eaten, the small size may indicate little nutritional value. Larger-bodied male araneids may be advantageous when mating on a mating thread because the thread is constructed from the edge of the web orb to structural threads or to nearby vegetation.<ref name=Elga91/> Here larger males may be less likely to be cannibalized, as the males are able to copulate while the female is hanging, which may make them safer from cannibalism.<ref name=Elga91/> In one subfamily of Araneid that uses a mating thread, Gasteracanthinae, sexual cannibalism is apparently absent despite extreme size dimorphism.<ref>{{cite journal |last1=Elgar|first1=M. A. |title=Sexual dimorphism in leg-length among orb-weaving spiders: a possible role for sexual cannibalism |journal=Journal of Zoology (London) |year=1990 | volume=220 | issue= 3| pages=455–470 | doi=10.1111/j.1469-7998.1990.tb04044.x}}</ref>