This large ciliate forages for food as it stands still among algal cells and particles. Its strategy for catching food is to vigorously move the cilia surrounding its broad mouth as it waits for small organisms to pass nearby and be sucked inside. In the course of our observation, several small organisms are drawn into the body, followed by a diatom and a flagellate. However, some of them are rejected and cast out through the membrane.
Commentary by Prof. Yuji Tsukii, Hosei University
This organism is not Euplotes, as in the title states, but Stylonychia.
We can easily distinguish Stylonichia and Euplotes if we know what to look for.
Euplotes has a few large cirri around the top, slightly behind the center, and at the rear end; but there are no small cirri along the sides. On the other hand, Stylonychia has small cirri around its oral part (peristome) and lining both sides of the body. Stylonychia also has three long caudal cirri extending backward.
Stylonichia and Euplotes largely differ from each other in the number and shape of their macronuclei, although we cannot distinguish these characteristics in living organisms. Stylonichia has two ellipsoidal macronuclei (one at the top and another at the rear), whereas Euplotes has one large macronucleus with various shapes depending on the species, such as T-shaped and C-shaped.
Sampling Date : 27 May 2009
Sampling Site : Hirose River A Google Map