Most oomycetes produce two types of spores. The main dispersing spores are asexual, self-mobile spores called zoospores. These do chemotaxis (movement toward, for example, a food source) in surface water. A few oomycetes produce asexual spores that are distributed by wind. Oomycetes also produce sexual spores, called oospores. These are translucent, double-walled, spherical structures which can survive adverse conditions.