Chytridiomycota is a phylum in the
kingdom Fungi. The name is derived from the
Greek chytridion, meaning "little pot", describing the structure containing unreleased
zoospores. In older
classifications, chytrids (except the recently established
order Spizellomycetales) were placed in the class
Phycomycetes under the subphylum Myxomycophyta of the kingdom Fungi. Previously, they were placed in the
Mastigomycotina as the class Chytridiomycetes. Also, in an older and more restricted sense (not used here), the term "chytrids" referred just to those fungi in the
order Chytridiales. Here, the term “chytrid” will refer only to members of Chytridiomycota. The chytrids have also been included among the
Protoctista, but are now regularly classed as fungi. Chytrids are one of the early diverging fungal lineages and are
saprobic, degrading refractory materials such as
chitin and
keratin, or acting as
parasites. Their membership in kingdom Fungi is demonstrated with chitin cell walls, a posterior whiplash flagellum, absorptive nutrition, use of
glycogen as an energy storage compound, and synthesis of
lysine by the a-amino adipic acid (AAA) pathway. There are approximately over 750 chytrid species distributed among 7
orders. There has been a significant increase in the research of chytrids since the discovery of
Batrachochytrium dendrobatidis, the causal agent of
chytridiomycosis.