Mating Strategies in Araneomorphs: the Pros and Cons

pannaking22

Arachnoemperor
Old Timer
Joined
Nov 25, 2011
Messages
4,226
While having a stimulating conversation here on AB with a couple members, I thought I would toss up a thread discussing different breeding strategies found in the various true spider families/genera/species. For a nice little talk on Latrodectus hasselti, look here. While Latrodectus may be one of the most well known spiders with regards to mating, there are plenty of other groups that exhibit interesting behaviors when attracting and/or selecting mates or breeding.

One oddity that cropped up not too long ago and was featured by many small online news outlets (shocking, I know!) is the coin spider in the genus Herrenia. After mating, the male will castrate himself in order to plug up the epigynum of the female and become lighter and more agile so he can mate-guard the female he just mated with. This is an interesting tactic all in itself because while male spiders in several species will break off at least part of their emboli to serve as a plug, self-castration is a little bit odd. The evolutionary selection for this strategy must have been extraordinary, with my assumption being that males are extremely prevalent, while females are few and far between. I would be curious to see what happens if a virgin male is able to get past the castrated fellow and mate with the female.

There are a couple other examples I can think of, but I'd rather have others weigh in first to see if this thread is worth keeping going and because I'm sure you all know some pretty crazy stuff I haven't come across yet :D
 

The Snark

Dumpster Fire of the Gods
Old Timer
Joined
Aug 8, 2005
Messages
11,046
This might be fairly well-known, but the size differential in (at least some species of) Nephila is so great that the females don't even notice when males mate with them. Presumably, this avoids cannibalism (or at least that's been my assumption).
https://c4.staticflickr.com/4/3249/3123990023_a7379f3dfc_b.jpg
Neph males commonly live in communal groups in the females web, munching the bugs too small for her to bother with. Add that to your formula.
 

pannaking22

Arachnoemperor
Old Timer
Joined
Nov 25, 2011
Messages
4,226
Neph males commonly live in communal groups in the females web, munching the bugs too small for her to bother with. Add that to your formula.
Do you know of any competition between males then to mate with the female? And do males show up and hang out in the web before maturing or after? I'm just asking because when I visited South Carolina a couple years ago, I would run into webs that had several Nephila hanging on. Various sizes, most likely immature, but it seemed like both males and females present. Are these guys semi-social or would this qualify more as tolerant?
 

The Snark

Dumpster Fire of the Gods
Old Timer
Joined
Aug 8, 2005
Messages
11,046
Do you know of any competition between males then to mate with the female? And do males show up and hang out in the web before maturing or after? I'm just asking because when I visited South Carolina a couple years ago, I would run into webs that had several Nephila hanging on. Various sizes, most likely immature, but it seemed like both males and females present. Are these guys semi-social or would this qualify more as tolerant?
Good question I can't even attempt to answer. I have a problem when it comes to orb weavers, especially the larger ones. I find them the most attractive and, for lack of a better word, endearing, of all the spiders. So I'm biased and scientifically invalidated.

But, going by observations mostly of nephs, they are extremely discerning and meticulous. They are very fussy housekeepers for a start. A messy crap filled web almost always equates to a sick/dying female or about to abandon her web and lay eggs. They ignore many insects that get in their webs. If the undesirable insect doesn't free itself she just waits until it is dead then extracts or cuts it out of her web. They have a very precise criteria as to what is food very similar to insectivore bats. And don't toss out bats use echolocation. They also have an acute sense of smell. But both only want a winged fluttering prey. Nephs are also extremely conservative motion wise. They only repair their webs at certain times and those times appear to coincide when insectivores as bats and birds are not out and about. At all other times they remain completely immobile being so vulnerable to predators.

So IMHO, nephs could be very tolerant of other spiders, especially of their own genera, in their webs. And of course, due to their size, the idiot squads and Machiavelli's like the Portia's would be more along the lines of comic relief than any form of competition.
 

schmiggle

Arachnoking
Joined
Nov 3, 2013
Messages
2,220
Apparently, male Pisaura mirabilis, a nursery web spider, offer females a nuptial gift and then mate. They also often pretend to be dead while mating.
https://en.wikipedia.org/wiki/Nursery_web_spider
Concerning Nephila, this paper says that Nephila clavipes males compete for a prime spot in the web of a female, and that those near the center monopolize both access to the female and bits of her kills. There is some mortality caused by females eating the males, not connected to distance from the female, but the male-female size difference in Nephila clavipes seems to be relatively small, at least compared to the species in the picture I found.
http://link.springer.com/article/10.1007/BF00302697
And finally, also concerning Nephila, this paper says that in Nephila plumipes, the male is eaten 60% of the time after mating, but that actually increases his mating success. Nephila plumipes has a massive size differential, so perhaps the book where I read about the male just not being noticed was mistaken, or I was misremembering. It seems unlikely that Nephila females would fail to notice a male if they keep their webs as clean as Snark has said.
 

klawfran3

Arachnolord
Old Timer
Joined
Feb 6, 2013
Messages
645
Do you know of any competition between males then to mate with the female? And do males show up and hang out in the web before maturing or after? I'm just asking because when I visited South Carolina a couple years ago, I would run into webs that had several Nephila hanging on. Various sizes, most likely immature, but it seemed like both males and females present. Are these guys semi-social or would this qualify more as tolerant?
supposedly there are reports of male Nephila sp. hanging around immature females webs until they mature so they can mate with them. Does that count?
 

pannaking22

Arachnoemperor
Old Timer
Joined
Nov 25, 2011
Messages
4,226
Great stuff everyone!

supposedly there are reports of male Nephila sp. hanging around immature females webs until they mature so they can mate with them. Does that count?
Hmm, I guess it would? Seems like a good way to stake his claim lol.

I vaguely remember reading something about a species of wolf spider where the males only mate with virgin females and will consume non-virgin females...I'll have to dig around for that article again. I know that definitely doesn't make sense in terms of reproduction and evolution!
 
Top