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Weekly “What is it?”: Chocolate Tube Slime Mold

The plasmodium of Fuligo septica slime mold consuming bacteria and fungi inside the office worm bin. Photo by Molly Jameson, UF IFAS Extension

I am not going to lie; slime molds are weird. They are weird in a “star role in a cheesy 70’s horror flick” kind of way. They come in nearly every shade of the rainbow and a wide variety of shapes, from fluorescent yellow piles and large white “eggs” to pink bubble gum or tiny black splotches. Common names for slime molds range from the illustrative “dog vomit” and “scrambled eggs” slime mold, to red raspberry and our feature today, chocolate tube slime mold.

Defying the human need for orderly classification, researchers have switched slime molds from the taxonomic Kingdom Fungi (mushrooms) to Protist. Protista is reserved for the most basic organisms, like amoebas, but the ancient slime molds still have a wide variety of interesting categories and traits. Slime molds are divided into three main categories: cellular (individual cells living solitary lifestyles), slime nets (combined cells that form a “slug” to share food), and plasmodial. Plasmoidal have the fascinating capability of working as a slow-moving (1” per hour) ooze that feeds on microorganisms. Even though these slime molds are made of single celled masses, they function similarly to a higher order brain. Scientists have even coaxed slime molds into following mazes and organizing into live “maps” of national transit systems.

Chocolate tube slime mold attached to a door. Photo credit: Jimbo Meador, Florida Master Naturalist

I first became aware of chocolate tube slime mold after one of our Florida Master Naturalists sent me a photo, asking what it was. The organism in the photo appeared to be the size and approximate shape of a sea urchin, but was attached to the top half of a door. It was brown and composed of a series of tubes extending 180 degrees. After a quick poll from fellow Extension agents, I learned its name. The chocolate tube slime mold, Stemonitis splendens, is typically found on rotting material, finding food and nutrients on the forest floor.

When triggered by the right (often stressful) environmental conditions, the slime mold starts forming reproductive fruiting bodies. These extend out, and often up, forming tubes that serve as platforms for releasing spores into the air.

The hot, humid weather conditions we are experiencing right now are ideal for finding slime molds. Look around your yard, or in the woods on a nearby trail—the odds are high that you’ll come across one of these fascinating, multi-colored organisms.