Ectocarpus belongs to Phaeophyceae (brown algae), where sexual reproduction involves gametes that are pyriform (pear-shaped) and bear two laterally attached flagella. In contrast, Polysiphonia (red algae) reproduces sexually by non-motile gametes, Spirogyra (green algae) involves the fusion of non-flagellated (non-motile) gametes, and Anabaena (cyanobacteria) does not produce flagellated gametes , , .