What’s in the sac? (no spider photos)


I’m working on my spider-wrangling skills, so Mary and I were tinkering in the lab today, and I tried opening up one of the many egg sacs I’ve got now. Guess what it’s full of?

Comments

  1. komarov says

    Nope, definitely a spider-video, at least if we were to apply anti-abortion logic.

    A sort of follow-up question from the video: Can the eggs survive outside the sac? Does the sac just serve as a wrapper or does do anything for the eggs, e.g. provide a more stable environment or something among those lines?

  2. sparks says

    That was fan-fucking-tastic! Thank you PZ.
    As an aside, not a biology major, but I’m betting the the sac does nothing for the wee little spideys outside of protecting them as a wrapper. Maybe some thermal deal is going on here?

  3. komarov says

    Re: Sparks (#2):

    As a layman striking out into the blue I was thinking about moisture. Maybe those eggs could dry out if not wrapped up.

  4. says

    I worry about moisture, too. But I think it’s mainly to protect them from parasites and predators.

    I mentioned that opening up the spider egg sac was a heck of a lot easier than dechorionating zebrafish eggs, and in the lab environment, that chorion is kind of useless. It protects them from friction, and that’s about it. You can rip the chorion of a fish egg and it will develop just fine — in the shelter of a petri dish.

    I also mentioned grasshoppers. Grasshopper eggs have one feature that’s very annoying — they’re pressurized. Punch a tiny pinhole in one, and the contents spew out in a tight stream, which tends to tear the embryo to shreds. You’ve got to do a fast, large tear so you don’t get the firehose effect.