Slime Mold

It’s been raining pretty much every day here lately, and evidently it’s a good time to be a slime mold.  On Monday I came home to find this one oozing along on the old hickory stump at the edge of my yard:

I’m completely ignorant of slime molds, but I took this opportunity to finally take a look at the Illustrated Guide to Common Slime Molds (by Peter Katsaros) I bought earlier this year.  This one appears to be Fuligo septica, the same species that caused a stir in the town of Garland, Texas in 1973, to the point where citizens demanded that the Governor call in the National Guard.  This was after firemen had tried to destroy it by hosing it down, which only caused it to grow larger.  A mycologist arrived on the scene after reading about it in the paper and was able to calm everyone down.

This slowly creeping stage of a slime mold is called the plasmodium, and it is feeding on microorganisms while in this form.  It is an ephemeral stage, and when I checked on Tuesday the slime mold in my yard looked like this:

This is the final, spore-producing state, called the sporophore.  The remains of part of the plasmodium were left behind in what looks like a tangled mass of spider silk:

On Wednesday the sporophores had darkened.  It looks pretty much the same today.

It has been demonstrated that slime mold spores can still be viable after sixty years, and they probably can last a lot longer than that.  Many insects feed on them, in some cases helping to disperse them, and at least one family of beetles (Sphindidae, the “cryptic slime mold beetles”) consists entirely of species that feed exclusively on slime molds both as larvae and as adults.  I suppose I should keep an eye on the sporophores and see who shows up.

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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7 Responses to Slime Mold

  1. Marvin says:

    My knowledge of slime mold was virtually non-existent. Now I know more. Thank you.

  2. jamieagius says:

    I am fascinated by these creeping organisms. Cool piece on ’em!

  3. Mary Holland says:

    I gather that slime molds are not considered fungi? How do you tell one from the other? Thanks!

    • Slime molds were grouped with fungi at one point, but they no longer are. I think the feature that most clearly distinguishes them is the mobile, food-consuming immature stage, the plasmodium. Distinguishing slime mold sporophores from fungal fruiting bodies may not always be easy, and probably requires microscopic examination until one develops a gestalt sense. Wikipedia has more information about slime mold classification, which seems to be messy and not fully resolved.

      Incidentally, I just learned from Wikipedia that the slime mold featured here has been given the common names of “dog vomit slime mold” and “scrambled egg slime.”

  4. Pingback: Slime Mold Beetles | BugTracks

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