Scientists have now figured out why the spider does this. When the spider removes his genitals, he becomes lighter on his feet, and he is better equipped for keeping rivals away from the impregnated mate.
Majaz Kuntner, a researcher at the Slovenian Academy of Sciences and Arts, said that the small spider produces enough sperm to fertilize a single large female’s eggs. Kuntner continued, saying that he chooses to monopolize a female by mutilating his genitals in the female spider’s genitals, which blocks access to the female’s reproductive organs.
Kutner said that this is an extreme type of monogamy. He said that the males put their eggs in one basket and they focus on just a single female.
Kutner showed his that another spider species breaks off its genitals during mating, instead of biting them off after mating. Kutner wanted to find out if this behavior had similar benefits, as spiders that break their genitals off during mating tend to be more effective bodyguards.
Kutner and his team gave individual males seven days to mate with a female. They then went on to compare the eunuchs’ behaviors with spiders that have never mated.
The team found that the spiders who were lacking one or both sperm organs after mating were more feisty than rivals. It was also discovered that the eunuchs remained around 50 percent closer to the females, and when compared to virgins, they attacked their rivals with much more aggression. They stayed active for around 40 percent longer than the spiders that didn’t mate, when they were harassed by a researcher paintbrush.
