A sudden change of direction
This is a comparatively large oval flagellate with two flagella. The shorter flagellum moves actively at the front, while the longer one trails behind. Usually the orgtanism travels in circles at a leisurely pace, but it is also capable of suddenly revising directions. We can see it passing easily between aggregates thanks to its thin, flat body.
Commentary by Prof. Yuji Tsukii, Hosei University
This organism belongs to genus Anisonema.
There is not enough information to determine its species.
In general, Anisonema acinus can exhibit several cell size and either soft or rigid long flagella extending backward, so it is uncertain whether these organisms are the same or not.
The Anisonema in this video is 100μin length, which is much larger than the cell length reported in reference books.
Therefore it is better to classify the organism simply as Anisonema sp.
Sampling Date : 03 July 2009
Sampling Site : Hirose River B Google Map