A fast swimmer
This reddish-brown oval ciliate is 200 microns long. It swims so quickly that it is difficult for us to follow its movement. After changing directions, the organism disappears from our view in a flash.
Commentary by Prof. Yuji Tsukii, Hosei University
This organism is Nassula because it has a characteristic structure called a cyrtos, and a flat, cylindrical body. Nassula feeds on a kind of blue-green algae called Oscillatoria, so immediately after feeding, Nassula turns a deep green blue green as well. As the food is digested, the color fades and becomes reddish like the Nassula in this video.
Sampling Date : 27 May 2009
Sampling Site : Hirose River A Google Map