Mighty Morphin’ Spiders

Last month, I thought I’d found a color morph in S. triangulosa: some recently caught wild spiders from Wisconsin that were almost solid black, with just a hint of the standard pattern. I figured I’d be able to do some crosses this summer and see if it was heritable.

Now I don’t need to! Look at the difference a month in the lab environment makes.

[I try not to splash spiders in your face here. You’ll have to look it up on Instagram or Patreon.]

That’s the same spider, almost a month apart. Now it looks all the other spiders I’ve got. I suspect it’s got to be something about the change in diet, from whatever they were finding in a garage to a steady diet of fruit flies and mealworms.

They were caught in Wisconsin, where they’d been living on cheese curds, brats, and La Croix, probably.

Also note that this spider has made a couple of egg sacs. The one in the top right is a half-assed mess, only a few eggs only partially wrapped in a thin skein of silk.


  1. wsierichs says

    So you’ve found Teenage Mutant Ninja Spiders. Can’t wait to see the movie!

  2. moarscienceplz says

    I’m not super surprised. I would imagine that changes in diet, temperature, age, hydration, and lots of other things could affect the colors of their exoskeletons, and since they shed the whole thing at once, it could be a pretty dramatic change even from one day to the next.

  3. silvrhalide says

    Coo!. And the white pattern is so pretty, like lace.

    One question though: why do you think that the difference in coloring is related to diet and not to something like temperature or amount of daylight hours? If you grabbed these guys from the wild in March and put them in your lab, I’m guessing the temperature swings in your lab are not as great as they are outside, particularly given the recent weather. (If they are, then I feel really bad for your students. And the spiders. Also, you might need to have a talk with maintenance.) Also guessing the light levels in your lab don’t vary as much as the outside world either. Maybe their coloration is more dependent on environmental conditions, like Arctic foxes or snowshoe hares, rather than diet. Just a thought.