A ciliate flees to safety
A thin oval ciliate 150 microns long stands still between particles as if it wants to conceal itself.
Long surface cilia that extend in all directions do not move at all. A membranous structure continuously trembles on one side of the body. When other organisms approach, it immediately darts behind another particles and stays hidden for a while.
Commentary by Prof. Yuji Tsukii, Hosei University
This ciliate is most likely Pleuronema marinum, which is one of the larger species in the genus Pleuronema.
There is a similar ciliate called Histiobalantium, but the whole cell surface of Histiobalantium is covered by two kinds of cilia both long and short. Because these cilia are not visible in this video, the organism can be identified as Pleuronema marinum. The shape of its body also indicates Pleuronema rather than Histiobalantium.
Sampling Date : 28 May 2009
Sampling Site : Hirose River B Google Map