Sphaeroeca volvox, although this species is found very often in plankton (location: 1;2;3), the specimens shown here were found in a treehole (see location (4) below). Focus plane on the flagella, which are about 30-40 µm long. In contrast to bicosoecid protists like for example Bicosoeca petiolata (with two heterokont flagella) the species Sphaeroca volvox belongs to the Choanoflagellates, and each cell has only one flagellum (see also image below).