Wildlife TV

Learn interesting and funny plant and animal facts with videos and photos

How do Spiders Mate?

on August 1, 2013

Arthropods are strange animals, from our perspective; those creepy-crawlies without backbones, that have multiple legs and exoskeletons. We find it easier to understand and empathise with other mammal species because we are (comparatively) closely related, but when it comes to arthropods, their behaviours can seem utterly alien and weird to us. This is very much the case when it comes to mating; the techniques and strategies they employ are sometimes gross and macabre, however, they never cease to be interesting and hopefully, with a little bit of a new perspective, we can try to understand and relate to them a little easier.

The mating behaviours we’re going to look at in this post belong to a specific group of arthropods called arachnids, most people know that spiders are arachnids (largely because of the term ‘arachnophobia’) but this group also includes ticks, mites, solifuges and scorpions. These animals are not insects, most notably because they have 8 legs instead of 6, and they are anatomically and behaviourally different too.

We’ll start with spiders (Order: Araneae), who are perhaps the most famous of the arachnids. Many spiders have very pronounced sexual dimorphism, (differences between males and females) often resulting in the males being much smaller and weaker than the females. There is very little romance in the spider world and the males have to mate faced with the risk of sexual cannibalism, where the female can use her great size and strength to potential eat him when he gets close to her. Spiders are opportunistic feeders and even if a smaller individual of the same species should find itself on their webs, they will take the chance to have an easy meal.

Golden Silk Orb Weaving Spider female surrounded by much smaller males.

The size difference between orb-web spider females and males is very striking.
The tiny males make an easy meal for her if she’s hungry.
Photo Credits.

The males in many species of spider exist largely just to mate with the females and as such have developed a range of strategies in order to survive their dangerous liaisons:

  • When a male approaches a web, he would like to make it clear that he’s not prey, so some males of some species will vibrate the web, from the edge, in a very specific rhythm that alerts the female in the center that a mating partner is approaching. The male will have to hope that the female is subdued and ready to mate by the time he crosses the web to meet her, or he’ll end up meeting the same fate as a fly would.
  • Stealth can be a useful tactic; a male Golden Orb Web Spider (Genus: Nephila) is so much smaller than the female, that he can sneak onto her web and mate with her without her ever knowing that he was there! Sometimes males will live on the female’s web for an extended period of time, stealing small amounts of her prey and taking great care not to alert her to their presence.
  • Some males are able to subdue a female by mounting her and massaging her abdomen with their legs which seems to pacify her and reduces the risk of her becoming aggressive and snacking on him during the mating process.
  • Alternatively, providing a delicious meal can help keep the male safe; males of some species will arrive at a female’s web and present a gift of a prey item such as a beetle, which keeps the female occupied while the male performs his duties and also keeps her attitude satisfied. Perhaps a nice dinner is the way to the lady’s heart?
  • An extreme strategy is used by certain Crab Spider males (Genus: Xysticus) which create a ‘bridal veil‘ for their mating partners. They spin silk around the head of the female and also her legs that trap her temporarily and prevent her from attacking him. Thankfully she can escape after a while once mating is complete.
  • Some species from the family of Jumping Spiders (Salticidae) practice dancing in their mating displays. These spiders have good eyesight, predominantly for hunting but also for the females to watch the courtship dances of the males as they prove themselves as strong and agile specimens, worthy of mating with.

Although mating dances are not usually set to music, they are still fabulous none-the-less, as demonstrated in this YouTube video:

http://www.youtube.com/watch?v=_K8G4eAXC88

A very unusual physiological ability is possessed by males of many species of orb-weaving spider whereby they can secure the opportunity to mate, whether the female scares them away or even eats them. Males deliver their reproductive material to the female by use of appendages called palps which transfer a packet of sperm (called a spermatophore) from the male to the female’s genital opening. These male reproductive organs are actually detachable and the male is able to attach them to the female’s genital opening permanently which means that he can run away to safety or simply be eaten by the female, safe in the knowledge that he will be mating with her successfully even if they do sacrifice some intimacy; a small price to pay for a chance at mating.

Spiders may not have a lot of romance, but the strategies they use in mating have allowed them to become very successful. I hope you enjoyed learning a bit about some of their reproductive techniques. In the next post we will look at another group of arachnids, the scorpions.

You can find more animals’ mating techniques on our series page.

Much love,

-Nick

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