An unusual large ciliate

A large, slender ciliate 500μin length is swimming quickly, twisting its flexible body like a ribbon. The front and rear ends are narrower than the main part of the body. The head appears black from the fine particles inside. The mouth of the organism looks oblique - slightly angled- to one side of the tip.

Commentary by Prof. Yuji Tsukii, Hosei University
This organism is in the genus Spathidium.

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

It is characterized by a slightly oblique (diagonal) mouth at the front end.

If the mouth extends to the side of cell, it may belong to a group other than Spathidium.

According to the sketches in Wimertiere oder Ciliata (1931, Kahl), the organism is most likely to Spathidium vermiforme (Penard) (p.160 - P.162) with a typical cell length of 200 - 400μm.

Sampling Date : 18 October 2009

Sampling Site : Hirose River A  Google Map