What Is a Slime Mold?

A slime mold may sound like a disease or an infection, but it’s actually a very odd plant. It’s so odd, in fact, that scientists once thought the slime mold was an animal. Because, like an animal, a slime mold can crawl!

A slime mold begins its life as a group of small cells that look like microscopic animals, moving about by whipping their flagella, or tails. These cells clump together to form a shapeless mass, an inch or more across. This mass looks and behaves like the one-celled animal called the amoeba.

Although it’s a plant, the slime mold can move during this stage of its life, crawling like a blob of jelly over rotting plant matter and eating bacteria and fungi. If you cut a slime mold in half, both pieces will live; if you put two molds together, they’ll become one.

Gradually, this jellylike blob takes on a definite shape, and it stops moving about. A slime mold at this stage of its life is usually too small to be seen without a microscope. Soon, the slime mold looks just like a fungus, or like a tiny, odd-shaped mushroom. Some slime molds look like birdcages; others look like umbrellas; and still others, like cattails, and they come in all colors of the rainbow.

The slime mold finally breaks apart and sends its seeds, called spores, into the air. These spores soon become crawling blobs of jelly all over again!