I know, even more arthropods, but that’s how it goes.
I’ve been keeping an eye on an Argiope spider in the dog fennel plants, probably a juvenile A. aurantia, sometimes known as a black-and-yellow argiope, or garden spider. These are the ones that grow fairly large, up to 8cm or more in leg spread, that throw orb webs with a white zigzag in the center across tall weeds or garden plants – generally, you discover them at waist height when right on top of them. This one is smaller yet still impressive for a spider, deep in the fennel plants and almost entirely hidden. A few days ago, a male had appeared and was hanging out at the edge of her web.
Many species of arachnid are sexually dimorphic, a 25 cent phrase important to biologists meaning that the females and males differ in appearance, in this case rather drastically in size. This evening as I checked, he had maneuvered closer to her and was sitting directly above her abdomen, which I took to mean courtship was imminent. It is apparently a tricky thing for arachnids, because the female can be choosy and, if I may use the word, irritable, so they tend to be circumspect. This male soon became quite active and I settled in to watch the whole affair.
He danced around the female a lot, legs fidgeting as if playing a complicated piano concerto, often going out to her leg tips – it almost appeared that he was securing her legs and I steeled myself for something kinky, but no webbing was actually in evidence. The female, for her part, twitched her abdomen slowly and rubbed her pedipalps against one another, but that was about the extent of her involvement. Refraining from comment.
Once the male had moved underneath her abdomen, where the nasty takes place, I figured he had it locked, and I was just waiting for the actual insemination to take place. The males produce sperm from their pedipalps, which is why they have that club shape, so the point I was watching for was when he inserted them in the female’s abdomen. I’ve only photographed this once, with a tiny species at very high magnification, and I was hoping for a better opportunity. Note that I was mistaken about the actual position of the testes in that post, though I could have sworn I’d read those details somewhere.
A bit of trivia. With some spider species, the males actually break off one of the pedipalps within the female (stop cringing,) which sometimes allows them to escape the female, but also may block the oviduct to prevent other males from impregnating her. The palps can continue to deliver sperm on their own, which seems a bit traitorous since, at that point, the female may be eating the male. This happens pretty often – the male has done his duty, and now does another by providing food for the female as she develops her eggs. Tempted as we may be to judge by our own standards, these really don’t apply to other species, and there’s something remarkably efficient in the whole process (even though the male does occasionally escape, not quite as sold on the idea as the female.)
And in a flash, the male was done, whether he’d managed to “break one off” or not.
I honestly didn’t see if he even made contact – it didn’t appear so – but the female’s immobility ended abruptly and he was trapped in webbing in a mere second, no cuddling or anything. It is entirely possible that he was an unacceptable suitor (but still full of protein,) and she waited patiently until he put himself in a position where he couldn’t escape. Or he may have made some comment about her butt. Spinnerets. Whatever.
I may go back out and detach his corpse from the web in a couple of days, to disentangle him and see if he still has both pedipalps, just out of curiosity. I’m treating this as a biological dissection because any other way it sounds extremely creepy.
In any event, when you’re tempted to consider our high divorce rate with dismay, remember that we’re a social species and this provides a certain perspective – it could be worse. Keep the pair, let her have the house, and live to see another day.