I love Dog Vomit

Slime mold! Dog Vomit Slime Mold!

A fantastic specimen growing on a decomposing cut log.

Dog Vomit Slime Mold that is! It’s one of those things while out in nature I just can’t resist taking another photo of, even though I have tons of photos already! I can never have enough dog vomit slime mold photos! 

Yellow is without question my favorite color, so really this slime mold is right up my alley. How could anyone pass up this gorgeous yellow blob while exploring. Fascinating! Gorgeous! Cooky! 

Scientifically and less gross sounding, the common name actually accounts for multiple slime molds. Both Fuligo septica and Mucilago crustacea on iNaturalist are known as Dog Vomit Slime Mold. But had many other variations as slime molds have an interesting taxonomic history, one that is still may change again in the future. For Fuligo septica, the more colorful of the two  it was first discovered in 1727 by a french botanist Jean Marchant, but later placed into its genus Fuligo in 1780 by a German botanist. 

M. crustacea likes to grown on damp grass (apparently), but all my observations are similar to where I’ve found F. septica which is in wooded areas, on logs, duff, and the forest floor. 

Like other slime molds, Dog Vom goes through different forms throughout its life history. Starting out yellow it eventually turns gray-ish, evolving eventually into a brown powdery orb which are the spores (see the right photo below). These spores will disperse via the wind into the surrounding landscape to hopefully form new slime molds. Spores are actually extremely durable as they must wait for favorable growing conditions, which could be years or decades!

But where does the yellow coloration come from? The slime mold produces a pigment known as fuligorubin A which makes it that gorgeous yellow. It can be attributed to its resistance to extremely high levels of zinc. Like most slime molds, this one is no different in having unique abilities to survive fine to normally toxic levels of different metals. F. septica has a special affinity to zinc, flourishing under levels of 4,000-20,000 parts per million. Wowza! With the researchers Setala and Nuorteva (1989) questioning how it can even live under such conditions. 

No longer in it’s prime, this Dog Vom is drying out.

Slime molds are found everywhere! From pole to the other (practically). While mostly found dwelling in the soils and decomposing vegetation of forests, you can find them in compost piles, and potentially other nooks and crannies. But these single-celled organisms don’t stay put, they move! Masses combine together to form bigger masses and move as one. The shape of this mass changes based on the environment by forming stalked bulbs, which are the fruiting bodies. These are what contain the spores I mentioned earlier. 

For more information on slime molds structure and physiology, this article out of Utah State University does a fantastic job. 

Slime mold’s ability to move that optimally covers an area. Oodles of youtube videos show slime molds replicating freeway systems in Canada, Japan and other countries. I have linked two below. This ability to efficiently cover an area has exciting perspectives to improve algorithms and aid in making actual decisions. Nuts! Just think of that,  a mold suggesting an optimal route of a new network of public transit or roads through a housing development. 


Trans-Canada Transport System: https://youtu.be/n4jRr7YAzfI 

Tokyo Railway System: https://www.youtube.com/watch?v=GwKuFREOgmo&ab_channel=TED


While reading more into this beautiful natural mold, I would come across so many articles starting out explaining that this blob is safe/harmless/non-dangerous/will disappear soon. I guess that’s my naturalist brain that experiences interest and fascination first instead of worry and disgust. Its safe folks, stop and enjoy the next time you find it!

What I referred to in this article: 

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