Some male spiders must give generous gifts to their female mates -- or die

In some spider species, males present their female love interests with gifts of insects, mostly flies.

Story highlights

  • Study: The bigger the gift, the longer a spider pair copulates
  • Scientists have long observed spiders' gift-giving rituals

(CNN)For some spider species, a gift to their spider lady love can mean life or death.

Scientists have long observed spiders' gift-giving rituals. But the spiders' generosity is not a result of chivalry or making the right moves to woo a mate.
    A study released this week revealed a deeper motive behind some of the male spiders' gift giving: self preservation.
    The study in the journal Biology Letters singled out nursery web spiders Pisaura mirabilis as among the species best known for giving "nuptial gifts" from males to females.
    Male spiders present their female love interests with gifts of insects, mostly flies, wrapped up in intricate webs.
    While it may seem like a show of affection, this offering lowers the chances of the male spider ending up as the female's dinner, the study says.
    And it can't be just any teeny weeny gift.
    In some cases, the bigger the gift, the longer the spiders' mating time, the study shows.

    Stingy male spiders end up dead

    In a study of more than 280 spider pairs, researchers discovered that females that ended up with stingy, no-gift males were six times more cannibalistic than females staged with generous, gift-carrying males.
    "The presence or absence of a gift was the most important factor in determining whether females cannibalized the males," the study says.
    Fifteen male spiders that tried to court without gifts were eaten even before they could mate, according to the study.
    "The results showed that pre-copulatory sexual cannibalism was enhanced when males courted without a gift," the journal Biology Letters said.
    The risk of sexual cannibalism for the nursery web spiders that didn't give gifts declined when mating occurred while the female was feeding, according to the study.
    Giving the female food doesn't eliminate all risks of getting eaten.
    In the study, one male spider that came bearing gifts was eaten after mating.