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Starving to be Social: The Odd Life of Dictyostelium Slime Molds

The views expressed are those of the author and are not necessarily those of Scientific American.

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Dictyostelium discoideum stalking up into a fruiting body. Earlier stages of growth are visible in the background.

I like to think I have an active imagination, but Dictyostelium discoideum is an organism so bizarre I could not have dreamed it up on my own.

Dictyostelium is a slime mold. It spends much of its time as an apparently typical microscopic single-celled amoeba, oozing about in wet soil grazing on bacteria. Something truly odd happens, however, when the food runs out.

Here is John Bonner’s classic time-lapse video of the slime mold in action:

Starving Dictyostelium band together to form a conglomerate organism. A multicellular slug of sorts, the group grows into a spore-making tower, a beacon for broadcasting amoebae out to richer grounds. The sudden lifestyle change is interesting enough, but the real evolutionary puzzle is the cells that comprise the delicate stalk. They die without reproducing so that cells in the fruiting body can turn into more effective spores. This form of altruistic sacrifice has fascinated biologists for decades. Here is an organism that is both solitary and fully, suicidally social, a near perfect model creature for understanding how multicellular life emerged from the amoebae.

I’m telling you all this because last week I had the fortune to visit the lab of Joan Strassmann and David Queller at Washington University in St. Louis. Strassmann and Queller head a research team dedicated to solving the Dictyostelium conundrum. I brought my photography gear, and below is a brief photo essay from an afternoon’s shooting.

Joan Strassmann examines a plate of cultured Dictyostelium.

A clean lab culture shows the consequences of a low food supply. Amoebae at lower right congeal into slugs.

A slice through a culture plate shows a progression of slugs (at left) to fruiting bodies.

In a fit of aesthetic playfulness, I placed a sheet of red paper underneath a culture plate to bring a bit of color to the slug-filled microscape.

Blue paper is also interesting.

Pink might be my favorite pairing for slime molds.

A "mexican hat" appears as a slug begins to sprout a stalk.

A mature fruiting body above a plain of rising stalks.

This fruiting body has emerged (along with some extraneous stringy fungi) from a fresh dirt smear on a lab culture plate.

Different species of slime molds have different fruiting structures.

Organized slime! On reflection, I probably could have titled this post as such.

Update (11/28): Some people have expressed an interest in ordering prints of these images, so I have set up a gallery: Dictyostelium photographic prints. Click the “buy” button to explore sizes and framing options.

For more information:

Alex Wild About the Author: Alex Wild is Curator of Entomology at the University of Texas at Austin, where he studies the evolutionary history of ants. In 2003 he founded a photography business as an aesthetic complement to his scientific work, and his natural history photographs appear in numerous museums, books and media outlets. Follow on Twitter @myrmecos.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. makinaro 4:29 pm 11/26/2012

    These are phenomenal! I wish I had these photos back when I was drawing comics about Dictyostelium behavior :)

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  2. 2. IncredibleMouse 6:13 pm 11/26/2012

    :) Got a good lol @ the colored paper. I have a slime mold factory of sorts (lots of decaying trees) in my backyard that never ceases to amaze me. I’m getting better at spotting them without having to wait for fruiting bodies. The wide range of them are truly beautiful creatures.

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  3. 3. TheHymenopteran 10:57 pm 11/26/2012

    Amazing photos as usual. These slime molds interested me a great deal in an evolution paper I did last year too. Such a nice study system, and very beautiful too.

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  4. 4. Saffy 6:38 am 11/27/2012

    I love those photos! They are amazing I remember being enchanted with things like Bryozoa and colonial organisms as an undergraduate :)


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  5. 5. sjfone 9:19 am 11/29/2012

    nerve regeneration?

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  6. 6. lucaspa 3:56 pm 11/29/2012

    A great intermediate in the evolution from unicellularity to multicellularity. Dictyostelium does both.

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  7. 7. Torbjörn Larsson, OM 5:46 pm 11/29/2012

    Also interesting is the stalk tip analog to epithelium that a paper points out, with the enclosed stalk cellulose+proteins as the underlying layer.

    The proteins used to hook the cells together are claimed to be ancestrally derived to some that we use similarly, but I guess the outcome is better seen as a demonstration of convergent evolution of tissues.

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  8. 8. Torbjörn Larsson, OM 5:49 pm 11/29/2012

    Here: “A Polarized Epithelium Organized by β- and α-Catenin Predates Cadherin and Metazoan Origins”,
    Daniel J. Dickinson et al, Science, 2011 March 11;
    1 .

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  9. 9. spokeofwheel 10:34 pm 12/3/2012

    All of you like to grow it, but for me it was a major pest( if my diagnosis was correct), There is a shhite load of it in the swimming pools of Folsom, CA. I was new in the business and really had no idea what was going on. I actually got pretty good after a couple years, but you guys have forgot more than I ever learned. Anyone have a couple moments to spare for a ditch digger?

    I could not get rid of it and it was “travelling” on my equipment. Poles, brushes, vacuum hoses, etc. I started soaking all of my equipment in chlorine to try to stop the spread. Are you talking about the same critter?

    Was there a simple solution? Like removing phosphates? You guys are in a complete different world than me but I sure would appreciate if one of you could take a few moments. I’m telling you I flunked high school chemistry and barely passed biology
    and would not even of had a clue that “pink slime” was extraordinary.

    Link to this

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