chelicerae

After mating, the male of Darwin's bark spider (Caerostris darwini) chews on his palps. The emasculation presumably renders the eunuch more aggressive, being better at fighting off rival males that might also want to mate with 'his' female. Credit: Research Centre of the Slovenian Academy of Sciences and Arts

Within the Ritualistic Arena of Spider Sex, Male Darwin’s Bark Spiders Add a New Twist