An unknown organism
An unknown organism stands still next to a particle. When observed in a time-lapse video, the particles inside the body move, which is usually a sign of life.
Commentary by Prof. Yuji Tsukii, Hosei University
The organism trying to catch a small diatom on a particle is too small to identify with certainty.
However, there are two features that suggest it may be an amoeba: 1) its slow movement; and 2) its rigid semicircle outline with cytoplasm moving inside.
The organism may be a small Arcella which is trying unsuccessfully to catch the attached diatom.
Sampling Date : 18 October 2009
Sampling Site : Hirose River A Google Map