Some Male Spiders Give Worthless Gifts to Their Prospective Mates

Male Paratrechalea ornata spiders offer silk-wrapped gifts to their prospective mates. In this image, a female (left) and male (right) are both holding a gift.
Maria Albo
(Inside Science) -- Male spiders that give females worthless gifts seem to bank on the idea that it’s the thought that counts -- even gifts that have no value give them more time to mate.
Paratrechalea ornata is a roughly bottle cap-sized semi-aquatic spider found in Uruguay and surrounding South American countries. Like other male spiders across the world, the males of this species give females nuptial gifts
“You all the time find males with worthless gifts,” said Maria Albo, an evolutionary biologist at the University of the Republic in Uruguay. Some males will wrap up their dried-up prey leftovers, while others will even stoop so low as to wrap up plant bits.
In a study
In another recent study, the researchers found that the males will often wrap up the larva molt for the female even when they have the option of giving a better gift. Albo and her colleagues found that the male invests more silk in wrapping
The worst thing is, the male doesn’t even fully give the gift up, worthless or not. Instead, he holds onto the silk with his third pair of legs during mating. “The silk can help him retain the gift if the female wants to run away,” Albo said.
In general, the idea of nuptial gifts is that they provide females with more food, helping to sustain them through pregnancy. Clearly, that doesn’t happen if the gift is worthless. Albo and her colleagues are now studying whether the worthless gift tactic evolved as a response to low food availability.