Members of the kingdom Fungi have cells with a nucleus. Fungi cells have a cell wall and membrane-bound organelles. The presence of membrane-bound organelles causes fungi to be classified as eukaryotes.
Most species of fungi are multicellular organisms. They are heterotrophs that must find their own food. Many fungi act as decomposers in their environment. They break down organic matter from organisms that are dead or dying and are considered to be the main source of decomposition for an ecosystem.
Fungi feed by secreting an enzyme that digests their food and then absorbs the nutrients. This process is called extracellular digestion. To get to a food source, a fungus grows towards it.