General morphology Zoospores are composed of a
microtubular cytoskeleton base which extends from the base of the flagellum. The complexity and structure of this cytoskeleton is variable and is largely dependent on volume and size. One common feature of zoospores is their asymmetrical shape; a result of the ventral groove housing the flagella base. Certain zoospores progress through different phases, the first phase commonly referred to as 'the initial'. illustrated in Fig. 1 at right: • Posterior whiplash flagella are a characteristic of the
Chytridiomycota, and a proposed uniting trait of the
opisthokonts, a large clade of eukaryotes containing animals and fungi. Most of these have a single posterior flagellum (Fig. 1a), but the
Neocallimastigales have up to 16 (Fig. 1b). • Anisokonts are biflagellated zoospores with two whip types flagella of unequal length (Fig. 1c). These are found in some of the
Myxomycota and
Plasmodiophoromycota. • Zoospores with a single anterior flagellum (Fig. 1d) of the tinsel type are characteristic of
Hyphochytriomycetes. • Heterokont are biflagellated zoospores (Fig. 1e, f) with both whiplash (smooth) and tinsel type (fine outgrowths called mastigonemes) flagella attached anteriorly or laterally. These zoospores are characteristic of the
Oomycota and other
heterokonts. ==Zoosporangium==