The Oomycetes are mostly zoosporic, and have coenocytic mycelia, The mycelium is well developed and resting sexual spores are oospores. Homothallic means that the same individual can produce sexual oospores. Heterothallic means that two different compatible thalli are needed for the development of oospores. One can be thought of as female and the other as male. Note that lower fungi are the only fungi with sporangia and zoospores.
Zoospores are biflagellate.
Cell walls consist almost entirely of cellulose and glucans, NO chitin. The oomycetes are not on the main line for fungal evolution. The only pathogen in this group is Aphanomyces vegetable root rot of Peas, Sugar beets. As with all of these fungi favoured by wet conditions. Motile zoospores and cause watery root rots of seedlings and mature plants.