Many different organisms, from mushrooms to mold to yeast, can be categorized as fungi. Approximately 150,000 species of fungi have been discovered and formally described; however, mycologists estimate that there are conservatively 3.8 million species of fungi on earth. We know only about 3.9% of all that exist in nature.

Fungi were once thought to be plants, because animals move and plants don’t. However, they have such distinct features that they are now considered to be in their own separate taxonomic kingdom. Here are a few things that make them unique:

Cell membranes: The cell membranes of animals, plants, and fungi are similarly composed of fatty lipid molecules, proteins, and other associated molecules. Fungal cells, like plants and animals, must maintain a specific fluidity of their cell membrane which is accomplished by a structurally rigid group of compounds collectively known as sterols. Whereas animal cells utilize cholesterol for this purpose, fungi uniquely utilize a compound called ergosterol. Interestingly, under certain conditions, the ergosterol in mycelium and mushrooms can be converted into vitamin D, which is biologically active in humans.

Cell walls: Fungi and plants need to maintain a high internal hydrostatic pressure, known as “turgor,” to maintain the diffusion of important biomolecules inside of their cells. Like the fiber mesh you can see embedded into the rubber of your gardening hose, cell walls help provide much needed structural integrity for cells to maintain their turgor. Whereas plant cell walls are mostly composed of cellulose, fungi produce a cell wall rich in beta-glucan and chitin (which also composes the hard shells of insects, crabs, and other arthropods). This incredible turgor is a major driving force for expansion which enables a mycelium to bore through dense obstacles in nature like rock and wood in their search for resources.

Bodies: Most people equate fungi in nature (or in supermarket produce sections) to mushrooms. Read more: https://bit.ly/40TSCIV