I planned to start mating spiders today, and got my first disappointment: I waited too long, I think, because several of the males had died. I think maybe they pined away with blue pedipalps. The males are definitely more fragile.

So then I fed a couple of mighty females so they wouldn’t be tempted to snack on the boys, and then introduced them to males. The males immediately scampered to the far side of the cage. No mating today, at least not that I’ve seen. I’ve left them together and hope the guys make it through the night.

A while back, I told you I had a slight problem: I probably had two nearly indistinguishable Parasteatoda species in my colony, P. tepidariorum and P. tabulata. The way to tell them apart is by close examination of their genitals, or by dissection, and a) I don’t have the skill to do that, and b) I’m trying to maintain a live, breeding colony, so taking individuals apart to figure out their sex is off the table.

I did hatch a cunning plan, however, to get a provisional identification. P. tabulata is known to build nests from scraps of debris and wind-blown litter, so I thought maybe I could get a tentative guess at their taxonomy by cluttering their cages with scraps and seeing who built homes for themselves. It’s not at all definitive, especially since they’re all living in a sheltered environment right now and even P. tabulata might find nesting superfluous, but I raided the department’s paper shredder and hole punch for little bits, and scattered them in all the tanks.

Most of the spiders ignored them. They couldn’t eat them, after all. But a few have slowly dragged bits and pieces of paper towards their roost and built little hidey-holes. Here’s Melisandre:

So maybe I can put together a rough behavioral test to estimate who is who? I don’t think a real taxonomist would be satisfied with it at all, but it’ll be useful for me, making it less likely that I send a P. tepidariorum male off to mate with a P. tabulata female, which probably wouldn’t go well.

By the way, P. tepidariorum is thought to be native to the Americas, that is, it hitch-hiked here with the first humans to move here; it colonized Europe when the human colonizers boats sailed back home. P. tabulata is probably native to Asia, and emigrated to the Americas and Europe much more recently. Both are thriving almost everywhere humans live now, but the timing would suggest that the two species diverged at least 15,000 years ago…or about 15,000 generations ago. It’s kind of neat how their morphology hasn’t drifted apart much, but their distinct genitalia make an uncrossable reproductive barrier.

Some students visited my spider-haunted office with a few questions, and they noticed…a spider descending from the ceiling. They shouldn’t have been surprised.

It was a jumping spider! I think they’re following me around now, because I’m finding spiders everywhere I go.

I know you’re in shock that I posted a picture of a bird (what is this blog coming to?), so let’s quickly compensate. I went into the lab this morning to see how the new lab-bred generation is doing, and they were looking great — they had nice webbing everywhere, they had slung some hammocks, and were hanging about looking comfortable, always a good sign. I ambled back to my office, took care of some student stuff, and took my time about getting back to snap a few vacation photos of happy spiders lazing in their new digs. In the time it took me to wander back, Lilith (S. triangulosa, obviously) had up and molted!

This is also a very good sign. The new spiders are getting comfy and growing.

I had set up a bunch of new cages for my new generation of lab-born spiders (I keep wanting to call them azi) yesterday, and I popped in this morning to see how they were doing. They’re looking great! They still seem so small to me, but they’ll grow, I’m sure.

One of the signs that they’re doing well is that they started filling up all the open spaces in their cardboard frames with cobweb. This little Parasteatoda has been zipping back and forth all night to make lots of strands of webbing.

They also seem to have eaten all the flies I gave them yesterday. I may have to give them a few more tomorrow.

This is how I spent my morning:

I was cleaning up cages to set up more space for the next generation of spiders. The previous generation were all wild-caught; these are all lab-born, raised in isolation, so they’ve never seen another spider, which is why they are all flagged with a big “V” for virgin. The plan is to let them get cozy in their roomy new boxes, put up some cobwebs to decorate the place, and then next week I’ll introduce males to them, one by one. I’m going to watch them and then, as soon as the male has accomplished his duty, I’ll scoop him right up and put him in a vial, nice and safe.

I’ve got more juvenile females to set up with cages, but the remaining spiders are still on the small side. These spiders are small, too, especially compared to the behemoths I caught at the end of the summer, but they’ve got to start sexing it up sometime.

My concern about my declining Parasteatoda population led me to check on the juvenile stock. They’re fine. They’re looking good. They look to be about 50:50 male:female, too, and the males are flaunting huge pedipalps, so maybe I should think about breeding them soon, even though they look so small compared to the big adults currently in the breeding cages. Here’s a quick look at the teenagers.

[Read more…]