Strobilidium with a protuberance

The first part of this recording shows a Strobilidium ciliate at a higher magnification, the second part at a lower magnification, and the last part is in slow motion at a higher magnification. There is a strange protuberance on the side of its body, but we do not know the cause of this abnormality, or if it has a particular function.

Commentary by Prof. Yuji Tsukii, Hosei University
Strobilidium can be difficult to distinguish from Strombidium due to their similar shapes and features.

The organism in this video is in fact Strombidium, not Strobilidium.

There are three species of ciliates with a similar shape: i) Strobilidium: cirri surrounding the mouth extend downwards.

http://protist.i.hosei.ac.jp/PDB/Im.....

ii) Strombidium: cirri surrounding the mouth are closed like a circle.

http://protist.i.hosei.ac.jp/PDB/Im.....

iii) Strombidinopsis：its shape is shown at the following link:

http://protist.i.hosei.ac.jp/PDB/Im.....

In this video, the cirri surrounding the mouth cannot be clearly identified.

However, the cell tapers at the rear, and with careful observation, we can see numerous stick-like structures arranged like a ring in the rear part of the cell.

These features are characteristic to Strombidium.

In Kahl’s Wimertiere oder Ciliata (Infusoria), two conjugating Strombidium sulcatum cells both have pointed ends.

Sampling Date : 18 October 2009

Sampling Site : Hirose River A  Google Map