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Female spider expects gift before sex…and it had better be a good one

 This photo shows a female with a white gift, and a male about to transfer sperm to the sperm storage organs under the rear part of the female's body.
This photo shows a female with a white gift, and a male about to transfer sperm to the sperm storage organs under the rear part of the female's body. Alan Lau

TORONTO – “At least buy me dinner first.”

That old joke may hold true for the Pisaura mirabilis spider, also called the nursery web spider, which researchers out of Denmark have found expect a gift before mating.

The female spider, which has relatively few eggs, needs to store a lot of sperm in order to increase the chance of fertilization.

So if a male produced a gift to her, such as an insect, she would choose to store more of the male’s sperm. A male who didn’t present a “nuptial gift” had less of his sperm stored.

Other animals – such as some ducks and insects – conduct similar gift-giving rituals in order to pass along the best traits.

And in what could be called the worst date ever, in two percent of cases, the female will eat the male after receiving a gift.

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Watch: Female spider consumes male

Not all gifts are equal

“Not all gifts were genuine gifts,” Trina Bilde, Professor of Evolution Ecology at Aarhus University in Denmark and researcher of the study told Global News. “Some males give away a worthless gift.”

The male spider, looking to hunker down for a night of passion with his desired female, wraps up a gift in silk and presents it to the female spider, but he may try to trick her: it may be an already-consumed insect.

He may think he’s pretty smart since he begins to get busy as she’s unwrapping the gift. However, she’s smarter: once she discovers the ruse, she may stop copulation or just decide not to store much of his sperm, thereby reducing the chance of reproduction.

Bilde and Maria J. Albo of Aarhus University, as well as Gabriele Uhl of the University of Greifswald in Germany, conducted the research over six months – and yes, that included counting the tiny sperm stored in the female.

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