One or more cells of algae transform to form zoosporangium. The protoplast of zoosporangium divides to produce two or more zoospores. These zoospores have two or four flagella and are motile. However, a single zoospore with many flagella is produced inside the zoosporangium of algae of class Oedogoniales and family Vaucheriaceae. It is called synzoospore. These zoospores germinate and give rise to new algae. Such as Ulothrix, Chara, Vaucheria, Ectocarpus, Oedogonium etc.