The Order Chytridiales is a group of primarily aquatic fungi within the phylum Chytridiomycota, often considered among the most primitive fungi. Members are typically unicellular or simple multicellular and are characterized by motile spores with a single posterior flagellum, which allows them to swim in water. They can be saprophytic, decomposing organic matter in freshwater and soil, or parasitic, infecting algae, plants, or amphibians. Notably, some chytrids, such as Batrachochytrium dendrobatidis, are responsible for devastating amphibian population declines worldwide. Chytridiales play important roles in nutrient cycling and aquatic ecosystems, linking microbial food webs and contributing to the decomposition of complex organic materials.