It’s mortality assessment day!

My large collection of baby spiders is much smaller now. This morning, I went through the whole collection, scrutinizing them carefully for health, and tallied up the end result of my breeding experiments. Then I gave everyone a last meal in their baby vials, because tomorrow I rip up their natal cobwebs and transfer each to new, clean, larger containers so I can raise them to full adulthood.

It was a grim morning. There’s been a steady die-off of spiders over the last two months, often occurring at molting — they sometimes seem to get stuck, and that’s the end of that. I had three separate lines of spiderlings: 1) The R (for Runestone) line collected from a female at Runestone park, well off the beaten track; 2) The H (for Horticulure) line collected at an outdoor building at the local Horticulture garden; and 3) The M (for Myers) line collected right here in my garage at home. There was considerable variation in mortality.

R line: 95% (!) ☠

H line: 75% ☠

M line: 50% ☠

Maybe I’m just terrible at spider husbandry. I don’t have a good feel for how much normal juvenile death I ought to expect. It’s possibly interesting that the line collected from an indoor spider thrived best in the lab, while the ones found in a rather ‘wilder’ environment did worst.

Today wasn’t great, but the survivors all look fat and handsome and healthy, and tomorrow they get moved to their new roomier abodes, and I’ll also take photos of them. I’ll probably flood my Instagram account with pictures of my pretty young spider children, so watch out for that.


  1. psanity says

    Ah! You fool! You removed the poor creatures from the energy field of their magical Runestone! Oh, the huma-, I mean, uh, the arachnidity!

  2. nomdeplume says

    I always thought that what must be a huge mortality among young spiders (because so few adults are seen relative to the large numbers from each egg sac) was the result of predation. But perhaps there is some other factor in the wild, like lack of food or disease.

    Can’t be relevant to your laboratory animals though. Two thoughts – is the diet, of one fly species, too restricted? And could there be some gut biome present in wild spiders which lab animals can’t have access to?

  3. blf says

    The mildly deranged penguin suggests the urbanised spiderlings (M) find it easier to get of their apartment blocks, stroll around, munch on the local wildlife (R), and return home undetected. The suburban spiderlings (H) hide under the blanketweb and munch on themselves. The rural (R) spiderlings are easy-to-catch because, she confidently claims, they aren’t used to indoor, much less apartment-style, living.

  4. says

    Diet is tricky, since it’s got to be small stuff — flies, gnats, mosquitos. Flies are what I can raise in the lab.

    There are parasites and diseases. Fungus/mold are dangers for spiders — I’m thinking next time I’ll have to set up a regular schedule of vial transfers and cleaning.

  5. nomdeplume says

    @8 Mosquitoes might also be possible for lab rearing, though not in Winter. I understand the problem PZ, just trying to suggest causes.