November 5, 2013
This video shows how nursery web spiders give gifts prior to mating. First we see a male wrapping an insect in silk and presenting the gift to a female, and shortly afterwards there is a transfer of sperm. After this, the male plays dead and is pulled away by the female. In the end, the male ends up as food for the female who killed him. (Video: Christina Tuni, Aarhus University)
It is not only human males who benefit from flattering that special lady with gifts.
In the world of nursery spiders it is normal for males to initiate mating by giving the female a gift – an insect prey wrapped in silk.
Now a new study shows that this courting behaviour actually pays off for the male nursery spider:
”Our studies have shown that the females store almost twice as much sperm from males who have given them a gift, compared to those who have not,” says Professor Trine Bilde, who heads the ‘Genetics, Ecology and Evolution’ unit at Aarhus University’s Department of Bioscience.
The new study is published in the journal Proceedings of the Royal Society B.
Male spider mates through ’boxing gloves’
Unlike most other spiders, the nursery web spider (Pisaura mirabilis) does not catch its prey in webs. It goes hunting for its prey.
Like all other spiders, however, the nursery spider has a thread, which it often uses to wrap up insect prey as a gift for the female.
While the female is feasting on the contents of the gift, the male may get the chance to crawl beneath her belly and transfer his sperm into her antheridium.
Bilde explains that during mating, the male keeps one of his legs on the gift, so he always knows what the female is doing – and whether she will try to run away with the gift.
The male then transfers his sperm through two small organs that look like boxing gloves and are located on his head.
”The female can store the sperm for a very long time and can activate and use it whenever she wants. Her eggs only become fertilised if and when she wants them to be fertilised,” says the researcher.