Temporal range: Devonian–Recent
M.J. Powell 2007
A. Braun, 1851
Chytridiomycota is a division of the kingdom Fungi. The name is derived from the Greek chytridion, meaning "little pot", describing the structure containing unreleased spores. In older classifications, chytrids (except the recently established order Spizellomycetales) were placed in the class Phycomycetes under the subdivision Myxomycophyta of the kingdom Fungi. Also, in an older and more restricted sense (not used here), the term "chytrids" referred just to those fungi in the order Chytridiales. The chytrids have also been included among the Protista, but are now regularly classed as fungi.
The chytrids are the most primitive of the fungi and are mostly saprobic, degrading chitin and keratin. The thalli are coenocytic and usually form no true mycelium (having rhizoids instead). Some species are unicellular. As with other fungi, the cell wall in chytrids is composed of chitin.
In Allomyces, the thallus (body) is attached by rhizoids, and has an erect trunk on which reproductive organs are formed at the end of branches. The life cycle has the ability to change from haploid and diploid generations. The haploid thallus forms male and female gametangia from which flagellated gametes are released and merge to form a Zygote. Gametes and female gametangia attract the opposite sex by producing pheromones. The germinated zygote produces a diploid thallus with two sorts of sporangia; thin-walled zoosporangia which release diploid zoospores resulting in a diploid thalli and thick-walled sporangia which after meiosis release haploid zoospores which form haploid thalli.
As a parasite
The chytrid Batrachochytrium dendrobatidis (itself commonly known as "Chytrid") is responsible for a recently discovered disease of amphibians, chytridiomycosis. Discovered in 1998 in Australia and Panama this disease is known to kill amphibians in large numbers, and has been suggested as a principal cause for the worldwide amphibian decline. In one example an outbreak of the fungus was found responsible for killing much of the Kihansi Spray Toad population in its native habitat of Tanzania. Another example is that it's also responsible for the extinction of the golden toad in 1989. The process leading to frog mortality is thought to be the loss of essential ions through pores made in the epidermal cells by the chytrid during its replication. 
The earliest fossils of chytrids are from the Scottish Rhynie chert, a Devonian-age locality with anatomical preservation of plants and fungi. Among the microfossils are chytrids preserved as parasites on rhyniophytes. These fossils closely resemble the genus Allomyces.
In popular culture
Tom Clancy's Splinter Cell: Fallout (2007), a novel by Tom Clancy, features a species of the chytridiomycota fungus that feeds on petroleum and oil-based products. The species is enhanced using nuclear radiation, increasing its survivability and rate of feeding. It is then used by Islamic extremists in an attempt to destroy the world's oil supplies, thereby taking away the technological advantage of the United States.
- Hibbett, D.S., et al. (March 2007). "A higher level phylogenetic classification of the Fungi". Mycol. Res. 111 (5): 509–547. doi:10.1016/j.mycres.2007.03.004. PMID 17572334.
- Saving Tiny Toads Without a Home, by Cornelia Dean. The New York Times. February 1, 2010.
- (Voyles, J., L. Berger, S. Young, et al. 2007. Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis. Dis Aquat Organ. 77: 113-118.)
- Taylor, T.N.; W. Remy, & H. Hass. (1994). "Allomyces in the Devonian". Nature 367 (6464): 601. doi:10.1038/367601a0.
- Michaels, David (2007). Tom Clancy's Splinter Cell: Fallout. Penguin Group. ISBN 978-0-425-21824-2.
|Wikimedia Commons has media related to: Chytridiomycota|
- Chytrid Fungi Online: by the University of Alabama
- Introduction to the Chytridiomycota: at the UC Museum of Paleontology
- Impact of chytrid fungus on frogs (Foundation for National Parks & Wildlife)
- 'Amphibian Ark' aims to save frogs from fungus
- The Aquarium Wiki Encyclopaedia on Chytrid Fungus and how it impacts amphibians kept as domestic pets.
- Chytridiomycota at the US National Library of Medicine Medical Subject Headings (MeSH)