I was in coastal North Carolina a few weeks ago and noticed that there were these huge spiders in correspondingly huge webs. A little Googling leads me to believe that they were banana spiders. Upon closer inspection it appeared that one spider, presumably the female, was in the center where you would expect it to be and then there was a much, much smaller spider lurking on the outskirts. I’m guessing that it was the male. There were several webs around an all had the same thing going on.
All this to get to my questions - what animal has the largest size disparity between male and females? What is the evolutionary advantage? Harder for her to kill and eat him? And, if that’s it, why hang around in the same web? Get busy and then get gone!
I assume you are referring to the Golden-orb-web spider.
Small spiders lurking around the edge of the web may either be parasitic species that steal prey from the orb-weaver, or males of the same species.
Large females can produce a lot of eggs, whereas small males can produce sufficient sperm while being tiny. There’s much more selection on females to be large.
Because they do have a big risk of being eaten, males may wait until the female is distracted to approach her. I once threw a roach into a web and while the female was busy dealing with it, a male dashed in, quickly mated with her, and then dashed back out.
One candidate is certain deep-sea angler fish, in which females may be 500,000x heavier than the male, which basically becomes a parasite attached to her body.
Sounds like the subject of a daytime talk show.
I think the phenomenon we’re discussing is sexual dimorphism.
That article also mentions anglerfish as an extreme example. Plants can be subject to sexual dimorphism as well.
Yes, specifically dimorphism in size. In mammals and most birds (with the exception of birds of prey) males are usually larger than females. In many other organisms it’s the female that is larger.
In mammals and most birds (with the exception of birds of prey) males are usually larger than females.
I believe hummingbirds would also be an exception where the females tend to be larger than the males.
No, that’s not true. Males are generally larger (and I’ve measured and weighed hundreds of them.)
Likely referring to this type, Colibri.
You’re certainly correct about it being a Golden Orb. But regionally - here in South Carolina, at least - this particular variety is referred to as ‘banana spiders’.
Big mofo’s, too. I’ve been out boating in the swamps and seeing one over my head is a less-than-pleasant experience.
Cool, thanks! Chalk another one up to high school science teacher fail. I distinctly remember “the females are larger because they have to produce eggs.”
What about territorial behavior? I have a single feeder that is often “guarded.” A bird will come in to feed and almost immediately be driven off. Other times a bird will feed unmolested and even tolerate another individual. I assumed it is a pair that has claimed the feeder as their territory and they defend it from interlopers. Is this likely?
The one you show is not actually a Golden Orb, but a Black and Yellow Garden Spider, Argiope aurantia. The Golden-orb Spider found in the southern US, and sometimes called Banana Spider in South Carolina, is Nephila clavipes. If you’ve seen them over your head it’s the latter, since Garden Spiders make their webs lower to the ground.
Well, don’t know the answers but am female and just want to comment on how much it sucks to be the physically weaker gender- I feel like I am at least 3 times weaker even compared to men who are old and out of shape. I hired a man to rip out a bunch of Ivy in my back yard and he did it in 3 hours, would have taken me a week.