A few unrelated groups of protists are considered funguslike because of similarities in appearance and lifestyle to the true fungi. You may have seen a water mold growing on a dead fish or insect in the water. The white cottony growth is made of fine filaments, resembling the filaments characteristic of fungi. Like fungi, most water molds obtain nutrients by decomposing dead organic matter.

Other organisms in this group are parasites. An example of a parasitic species is the species that causes the disease of potato plants called late blight. That disease contributed to the great famine in Ireland in the 19th century. Despite their funguslike appearance and their lack of chloroplasts, water molds are actually chromists, like diatoms and kelp!

The slime molds include a few distantly related groups of protists with a superficial resemblance to fungi. They have complex life cycles. Plasmodial slime molds have a feeding stage in their life cycle in which the organism is a large amoeboid mass called a plasmodium. You may have seen one as a brightly colored ooze on a rock or a fallen tree. Despite its size, a plasmodium is not multicellular. It’s a continuous mass of cytoplasm surrounded by a single plasma membrane, containing many nuclei. The plasmodium engulfs small organisms for food. It can move slowly across a surface by streaming its cytoplasm.

Another group of slime molds, called cellular slime molds, exist as individual amoebas while food is available. When food is scarce, they come together to form a multicellular mass. This mass can assume the shape of a slug, which can crawl about in search of a new food source.

Both plasmodial and cellular slime molds also resemble fungi because they develop fruiting bodies, called sporangiophores, which release haploid spores that disperse into the environment. Spores that meet with favorable conditions can germinate into active cells.

Copyright 2006 The Regents of the University of California and Monterey Institute for Technology and Education