A Spider in Madagascar Engages in Oral Sex
Darwin’s bark spiders produce the toughest known silk in the entire world. The stuff is ten times more resistant to breakage than Kevlar! But the arachnids' silk-making prowess rates second to their sexual prowess, apparently. A new study published to Scientific Reports shows that males of the species perform oral sex on females up to 100 times during copulation.
Researchers from the Scientific Research Centre of the Slovenian Academy of Sciences and Arts and the Smithsonian's National Museum of Natural History traveled to Andasibe-Mantadia National Park in Madagascar to get up-close and personal with Darwin's bark spiders, the males of which measure in at roughly 6 millimeters long, while the females stretch about 20 millimeters. The team intently observed 29 separate matings in both the laboratory and the wild. In all instances, the smaller males performed cunnilingus on the vastly larger females. As the authors arousingly described:
"Typically, a performing male first hooked one of his cheliceral fangs to female’s copulatory opening, turned his body perpendicular to the female, then orally secreted fluids into the copulatory openings."
Marvin Gaye couldn't have said it any better.
The researchers suggest two likely hypotheses for the behavior. First, oral sex may signal mate quality -- to the better-skilled and more physically able male go the spoils! Second, enzymes in the males' saliva may render the environment inside the females' genital organs more hospitable to their sperm.
Oral sex is well documented in mammals. Notable givers include macaques, lemurs, bonobos, hyenas, cheetahs, lions, dolphins, bats, and (of course) humans. But throughout the rest of the animal kingdom, the act is not as well known. Male fruit flies lick female genitalia, an action that's rewarded with longer mating bouts. Also, there are spotty reports of oral sex occurring amongst widow spiders.
The researchers also observed bark spiders engaging in other risqué sexual acts, including sexual cannibalism, where the female eats the male, and mate-binding, in which the male envelopes the female in silk to avoid said cannibalism. Believe it or not, these acts weren't nearly as surprising as the oral sex.
Source: Gregorič, M. et al. Spider behaviors include oral sexual encounters. Sci. Rep. 6, 25128; doi: 10.1038/srep25128 (2016).