種名： Saprolegnia
Department of BiologyThe University of AkronOhio, USA Prof. Donald W. Ott
Zoosporangial release of primary zoospores of the water mold, Saprolegnia, parasitizing a gall formed by the parasitic rotifer, Proales, on a coenocytic filament of Vaucheria. The primary zoospores of Saprolegnia have two flagella located apically. If you notice, the spores come out of the sporangium backwards (being propelled by the apical flagella), then straighten themselves out and zoom foward. They then swim for a few minutes, encyst, and eventually produce the secondary zoospore with laterally inserted flagella. This spore will settle down and produce a new filament. This is described as a dimorphic asexual life cycle. The two spore stages allow the water mold to have two periods of motility to populate the pond or puddle and find new host.
(2015.03.17)