Amazingly long earthworm-like ciliate
Large ciliates typically reach 500 microns in length, so this giant specimen may be a world record holder at 2000 microns in length. One end appears to be fixed some long green algae as it waves the rest of body slowly back and forth. Its long body sometimes kinks and bends and we can see the cilia on the body surface vigorously moving.
Commentary by Prof. Yuji Tsukii, Hosei University
This organism belongs to genus Spirostomum.
As it has only one macronucleus, it is likely to be Spirostomum teres. However, the whole body is slightly longer than that of a typical Spirostomum teres, and its shape is similar to Spirostomum intermedium. Spirostomum intermedium usually has macronuclei connected with each other almost like prayer beads. In the case of Homalozoon vermiculare, the connected macronuclei merge into a single macronucleus before division.
A similar change may occur in the nuclei of S.intermedium, though this has not been confirmed yet. Therefore this video is probably of a Spirostomum intermedium before it begins dividing.
Sampling Date : 27 May 2009
Sampling Site : Hirose River A Google Map