Major Groups of Fungi Over 80,000 species of fungi have been identified, and there are many more. About 430 million years ago fungi started invading the land. Characteristics of Fungi Nutritional Modes Fungi are heterotrophs that use organic matter. All fungi rely on extracellular enzymatic digestion and absorption. Fungi are valuable decomposers in the environment.
Most fungi are multicellular.
The food-absorbing part of the fungus is a mesh of branching filaments called the mycelium. Each tubular filament is a hypha with chitinous walls. Interconnections and perforations allow cytoplasmic flow necessary for transport to nonabsorptive parts of the body. Reproductive Modes Asexual reproduction is mostly by spores produced in sporangia. Sexual reproduction proceeds through the formation of gametes in gametangia as well as by spores.