Introduction
The Kingdom Fungi includes eukaryotic,
generally multicellular organisms with an unusual form of multicellularity.
Their cells are not entirely divided by cell walls, so cytoplasm and even nuclei
can flow between individual cells. The cell walls are made of chitin, a
protein also found in the exoskeletons of arthropods, which reflects the close
relationship between the Fungi and Animalia kingdoms. They are more closely
related to each other than they are to plants.
Fungi are split between acting as
parasites,
which prey on insects, plants, and animals, and
saprophytes, which primarily aid in the
breakdown of dead organic material. Fungi can also live in symbiotic
relationships with other organisms. Lichens are the result of a symbiotic
relationship between a fungus and a
photosynthesizing organism. Other fungi
live
in symbiosis with plant roots to increase the root surface area.
Fungi can be divided into three groups based on relatedness and shared
reproductive habits: Basidiomycota, Ascomycota, and Zygomycota. Basidiomycota
are characterized by the presence of basidia and dikaryotic fruiting
bodies and include the mushrooms, puffballs, and shelf fungi. Ascomycota are
characterized by the presence of asci and include such diverse organisms as
the cup fungi and mildews as well as the unicellular fungi, yeast. Zygomycota
are characterized by the presence of a thick-coated zygospore and include
bread and other molds, plant and animal parasites, as well as many plant-root
symbionts.
