Portrait of a zoospore (motile reproductive cell capable of transformation into another developmental stage but incapable of sexual fusion) of the filamentous green alga, Oedogonium. The ovoid to elongate zoospore bears a wreath of flagella around an anterior hyaline dome. Reproduction in Oedogonium may be asexual, by means of large flagellated zoospores (motile reproductive cells capable of transformation into another developmental stage but incapable of sexual fusion) or oÃ¶gamous with fertilization of oÃ¶gonia by antherozoids (motile male gametes structurally similar to zoospore but smaller). Release of zoospores is followed by a short swarming phase that ends by the zoospore coming to rest with its flagellated hyaline dome at the substratum, shedding its flagella and then forming a holdfast. A new filament then forms by repeated intercalary and distal terminal cell divisions. The zoospores of algae may be confused zoochlorellae bearing ciliates (e.g. Cyclotrichium viride) but are distinguished by the absence of other somatic cilia or somatic kinetosomes. Collected from freshwater pond near Boise, Idaho in October 2003. DIC optics.