Yellow-fuzz Cone Slime (Hemitrichia clavata) is a slime mold that is found in clusters on rotting wood. Neither a plant nor an animal, slime molds are known for the dramatic transformations they go through from the time they first appear to their disintegration. Slime molds are slimy and mold-like when they first emerge, but they soon change color, shape and texture as they develop.
Yellow-fuzz Cone Slime was named for its reproductive stage. When its gelatinous plasmodium starts fruiting, it forms tiny, round, shiny spore-bearing sporangia that can be orange to yellow in color. When the spores are mature, the top of these sporangia open up, creating goblet-shaped cups filled with yellowish, fuzzy threads interspersed with pale yellow spores. (These threads are thought to be involved in the dispersal of the spores.) The stages of Yellow-fuzz Cone Slime are so different that you might well not recognize that they are the same species.
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As usual, Naturally Curious readers submitted unbelievably creative ideas about the identity of yesterday’s Mystery Photo. Kudos to those of you who recognized that it was a slime mold. Slime molds look like a fungus, and reproduce with spores like fungi do, but are no longer classified as fungi. Slime molds are made up of individual organisms that form a mass called plasmodium. They can be bright orange, red, yellow, brown, black, blue, or white. These large masses act like giant amoebas, creeping slowly along and engulfing food particles (decaying vegetation, bacteria, fungi, and even other slime molds) along the way. If a slime mold is cut up into pieces, the pieces will pull themselves back together.
The most common species are in a group called plasmodial slime molds. They share one big cell wall that surrounds thousands of nuclei. Proteins called microfilaments act like tiny muscles that enable the mass to crawl at rates of about 1/25th of an inch per hour. A slime mold mass can actually navigate and avoid obstacles. If a food source is placed nearby, it seems to sense it and head unerringly for it.
As long as conditions are good, (enough food and moisture and favorable pH), the mass thrives. But when food and water are scarce, the mass transforms itself into spore-bearing fruiting structures. These typically form stalks topped by sphere-like fruiting bodies called sporangia that contain spores that are carried by the rain or wind to new locations. After they have been dispersed, each of these spores will germinate and release a tiny amoeba-like organism which, if it successfully finds and fuses with another similar organism, can then begin to feed and develop into a new plasmodium.
The pictured slime mold, Coral Slime (Ceratiomyxa fruticulosa), is one of the more common slime molds. It is unusual in that it produces its spores externally on small stalks, not in sporangia, which gives it a fuzzy appearance.
To watch a time-lapse video of slime mold moving, go to https://www.youtube.com/watch?v=GY_uMH8Xpy0.
Slime mold guessers are right! This is a slime mold — aptly-named “Dog Vomit Slime Mold” (Fuligo septica). Slime molds are not plants, animals, fungi or bacteria. This stage of a slime mold’s life cycle is called a plasmodium, which is essentially one giant cell with millions of nuclei. The plasmodium moves by slowly flowing over the ground, gradually engulfing and consuming fungi and bacteria that are present on decaying plant matter. You often find it on mulch that is regularly watered. Dog Vomit Slime Mold is harmless to people, pets and plants. In fact, it is actually edible. In some parts of Mexico people scramble it like eggs (and call it “caca de luna”).