How fungi make a living without sunlight
Plants build sugars from sunlight, water, and carbon dioxide. Mushrooms do not: they are the visible fruiting bodies of fungi, which release enzymes into their surroundings and absorb the smaller nutrient molecules those enzymes produce. A fungus might feed on a fallen log, living roots, or other organic matter. This mode of feeding is one reason fungi are classified in a kingdom separate from plants.
A shared chemical clue
The resemblance to animals shows up in cell chemistry, too. Fungal cell walls contain chitin, a tough material also used in the outer shells of insects and other arthropods. Plant cell walls, by contrast, are built mainly from cellulose. The shared material is evidence of biological kinship—not proof that a mushroom is an animal, since fungi have their own distinct biology.
What “closer to animals” means
Fungi and animals belong to the same broad evolutionary branch, called Opisthokonta, while plants belong to a different one. That does not mean fungi descended from modern animals or that mushrooms behave like animals. It means their lineages share a more recent common ancestor with each other than either does with plants.
The contrast is easiest to see in how they get food: animals typically take in food and digest it internally, while fungi digest food outside their bodies and absorb the results. So the next time a mushroom appears to spring from the ground like a tiny plant, remember that its feeding machinery is already at work in the material around it.
