Bad day in the lab

The good news: I’m getting roughly one new egg sac every week, so I’ve had one produced on 27 December, another on 4 January, and another this week, on 7 January. I can make progress with that level of production.

Except the bad news: that egg sac from December should have hatched out by now. I opened it up: mostly dead. There were a total of 35 eggs in it; 6 had made it to the postembryo stage, and then died; 4 had made it past the first instar, and then croaked; 24 were arrested in an earlier embryonic stage, and were clearly not going to make it any further. There was ONE second instar survivor, waving its legs weakly in the midst of the charnel house of its siblings. That’s not very good. I’m not even certain the survivor is going to make it — I put it in a little chamber of its own with a fruit fly it can try to eat.

The other egg sacs…well, I’ll have to wait and see. I isolated the one from 4 January, and like the December clutch, put it in a petri dish on a cotton pad, which I spritz with water daily. Unfortunately, I’m finding that the pad doesn’t seem to help, acting more as a dessicant, I think. So I threw out the cotton on that second clutch. I’m leaving the 7 Jan sac with its mommy, in a large vial. We’ll compare outcomes under those two conditions.

Another hypothesis for this problem is that my original wild caught stock produced vigorous clutches of spiderlings, where the majority were healthy and fine…and cannibalistic, which contributed to a rapid culling. All of the egg sacs recently have been the product of inbreeding between progeny of the extraordinarily fecund Gwyneth. So I’ve placed my sole remaining male, a son of Gwyneth, in the company of a daughter of Xena, and will, I hope, get a new outbred clutch to compare. Or maybe Xena1 will consume the puny male. It was tough to get Xena0 to put up with any mates at all.

It would be interesting if Parasteatoda were sensitive to genetic inbreeding, rather than this low output being a result of my poor spider husbandry skills. I’m so used to zebrafish and flies that don’t care if you cross an individual with its sibling, its offspring, its parents, its grandparents (The Aristocrats!), but it is possible that wild species that engage in more mixing might be carrying a higher load of recessive lethals…although I’d also think there’d be limits to how much mixing there’d be in a synanthropic species with limited mobility in adults. Maybe there’s a lot of juvenile ballooning going on that I’ve missed? I’ll have to keep my eyes open in the spring, and see how my garage gets repopulated.

I’ve also noticed something strange going on in my brain. The questions I’ve been asking myself have been shifting from the generally embryological to something more ecological — I might turn into an eco-devo guy yet.


  1. marcoli says

    Total bummer! I don’t know if there is a seasonal limitation, but you could recruit your students to bring you house spiders as breeding stock. Males or females.

  2. says

    I’m not seeing ANY theridiidids anywhere right now. It’s all pholcidae and salticidae. So there seems to be an effective seasonal limitation — I’d really like to collect some new wild stock to test my hypothesis, but it just ain’t happening right now.

  3. Snidely W says

    Just spitballing here:
    -Polyester fluff instead of cotton. Can be cleaned, sterilized, and since it adsorbs rather than absorbs should be less desiccating. I’m thinking stuff like pillow stuffing.
    -To possibly reduce male carnage, might some kind of compartmentalization with something like a piece of window screen be helpful? I don’t know enough about the mating of these critters to know if it would make mating impossible or not. But if not, the males might be a little safer. Probably not totally safe, I’d guess that if they can mate through a screen then they can bite through a screen.
    Bon chance.

  4. says

    I’m just ditching the padding altogether for now.

    No, they mate by clambering all over each other, and the male has to insert his palps into an epigyne at the base of the abdomen. A screen isn’t practical.

  5. ndirienzo says

    Hey PZ – Try widow spiders… I’ve done behavioral development work with them for several years and they’re fantastic lab spiders. Their egg cases take virtually no effort to hatch, and females will produce 7+ viable ones off a single mating in the lab. I have a huge number in the lab that I’m happy to mail your way.

  6. pardalote says

    What is wrong with you PZ. There are any number of sites describing how to keep and breed spiders as pets. Piece of cake. There are whole websites devoted to the activity.

    On a website called Arachnoboards, the comments about Parasteatoda tepidariorum:-
    “Easy to keep. Give her lots of webbing points and just toss food in once a week or so and she’ll be set. An occasional misting wouldn’t hurt.”

    “I have kept a few Parasteatoda tepidariorum (before I got into tarantulas), and I have lots of them living on my porch, in my shed, and about the exterior of the house. They are extremely easy to keep and are not picky about their setup or their food.”

    As for inbreeding Wikipedia has this to say about a related Genus within the Theridiidae.
    “These spiders are also a promising model for the study of inbreeding as their mating system co-varies with sociality, and all permanently social species are highly inbred.”
    How social are P. tepidariorum?

  7. says

    I have read the papers and arachnoboard. I mist twice a week and feed 3 x week. The adults are thriving — it’s the eggs that aren’t hatching properly.

  8. says

    Hoi PZ,
    In a past post you were worried that you had misidentified the species some of your spiders. Did you ever come to a definitive conclusion there? Is there a possibility that your F1 is an infertile hybrid between two closely related species, or would you not expect any eggs at all in that case?

  9. says

    They’re all Parasteatoda tepidariorum. I got some external input on that and confirmed their identity. So that’s not the problem.

    I don’t know what would happen if I crossed two related spider species — it might be tricky, since spiders are not very sociable and will eat any suspicious looking character that approaches.

  10. joebiohorn says

    It’s kind of cute watch PZ pretend to do actual science. Could we ask, however, for the kind of rigor he demands from folks undertaking work in, say, evolutionary psychology: hypotheses to be tested, experimental design, planned procedures for data analysis – that sort of thing?

  11. John Morales says


    It’s kind of cute watch PZ pretend to do actual science.

    It’s kinda cute that you imagine your opinion on what constitutes “doing science” (to borrow your idiom) has any weight whatsoever.

    Could we ask, however, for the kind of rigor he demands from folks undertaking work in, say, evolutionary psychology: hypotheses to be tested, experimental design, planned procedures for data analysis – that sort of thing?

    We could, but only one person (you) asks whether that can be asked.

    Care to ask the question, then, instead of asking whether you can ask the question?

    (You’re just like fluff; no substance there)

  12. joebiohorn says

    Krip Dyke @ 16. Could you recommend a half dozen of his most important publications to get me started? I went to the National Library Of Medicine Site, where basically all publications in biology are catalogued, and found no indication that PZ has ever published more than one or two original research articles. Am I missing a vast treasure trove of important contributions, or is my impression correct that PZ is a third rate scientist at a second rate institution and who likes to lecture real scientists, like Jerry Coyne, on how to do their jobs?