title: Spider behaviors include oral sexual encounters.
abstract: Several clades of spiders whose females evolved giant sizes are known for extreme sexual behaviors such as sexual cannibalism, opportunistic mating, mate-binding, genital mutilation, plugging, and emasculation. However, these behaviors have only been tested in a handful of size dimorphic spiders. Here, we bring another lineage into the picture by reporting on sexual behavior of Darwin's bark spider, Caerostris darwini. This sexually size dimorphic Madagascan species is known for extreme web gigantism and for producing the world's toughest biomaterial. Our field and laboratory study uncovers a rich sexual repertoire that predictably involves cannibalism, genital mutilation, male preference for teneral females, and emasculation. Surprisingly, C. darwini males engage in oral sexual encounters, rarely reported outside mammals. Irrespective of female's age or mating status males salivate onto female genitalia pre-, during, and post-copulation. While its adaptive significance is elusive, oral sexual contact in spiders may signal male quality or reduce sperm competition.
authors.affiliation: Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia.
authors.forename: Matjaž
authors.initials: M
authors.lastname: Gregorič
authors.affiliation: Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia.
authors.forename: Klavdija
authors.initials: K
authors.lastname: Šuen
authors.affiliation: Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia.
authors.forename: Ren-Chung
authors.initials: RC
authors.lastname: Cheng
authors.affiliation: Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia.
authors.forename: Simona
authors.initials: S
authors.lastname: Kralj-Fišer
authors.affiliation: Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Slovenia.|Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
authors.forename: Matjaž
authors.initials: M
authors.lastname: Kuntner
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D012726:Sexual Behavior, Animal; D013112:Spiders / Q000502:physiology*