Cellularlife on earth can be divided in three different domains – the eukaryotic, prokaryoticand archaea, within these, further sub distinctions can be made, resulting in abranched and complex description of life. Fungi belong to the eukaryotic domain, inwhich they constitute their own kingdom, besides the plant and animal kingdoms.Similar to other eukaryotic cells, fungi cells contain organelles plus a truenucleus, all contained within a membrane, while they differ to prokaryotic andarchae cells, by their absence ofchlorophyll and having a cell wall consisting of chitin .
The general scheme ofa fungi is relatively simple. Composing of a main body, a mycelium, made up bya branched network of tubes, hyphae. Through hyphae, nutrients are absorbed, inwhich organic carbon, from either living or dead biological organisms, functionas the main energy source.
Reproduction of fungi can occur in two separate, yetconnected, ways. Either reproduction takes place asexually, mainly through themeans of the release of small identical copies of parent fungi as spores, orreproduction occurs sexually. Sexual reproduction varies between differentphylums and therefore a generic description does not make sense. Instead adetailed description is integrated within the description of each phylum. The fungikingdom can be subdivided in 5 different phyla, these are named Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota and Deuteromycota.
Phylum Chytridiomycotaencompasses most fungi, which at some point in their life cycles exists as flagellatedswimming cells and these fungi are therefore, primarily, found in aquaticenvironments. These fungi reproduce asexually whena zoospore lands on a substrate, followed by formation of a cell wall around it- leading to creation of a fungi body. Long threads, rhizoids, attach to the substrateand through these nutrients are absorbed. After a period of feeding, the fungibody is converted into a sporangium, a structure which contains andsubsequently releases zoospores.
Sexual reproduction occurs by fusing zoospores,thus creating a diploid zygote, which then hardens and creates ameiosporangium. Later fusing of nuclei create meiospores, which can then swimaway and form a new fungi body. Fungi of this phyla are mostly harmless,saprotrophic fungi, although a few pathogens such as Batrachochytrium dendrobatidis, which causes chytridiomycosis in amphibious animalshave been found.