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Amoeba from a paddy field

After being collected from a paddy field, this sample was put on DNB agar plate (diluted nutrient broth with agar) with a drop of distilled water for 4 days, and then observed. In this video an amoeba is surrounded by a lot of bacteria as it moves in several directions. The shape of the amoeba changes as the cytoplasm streams toward the direction of movement.

Commentary by Prof. Yuji Tsukii, Hosei University
This naked amoeba belongs to genus Glaeseria.

The overall shape is similar to that of genus Saccamoeba, but the way of locomotion is different.

Pseudopods in the genus Saccamoeba move straight forward along their axis line. However amoebae in the genus Glaeseria suddenly protrude semicircular pseudopods with a constriction at the base, after which the cytoplasm flows into the newly formed pseudopods. The key difference is that amoebae in the genus Glaeseria do not move in a straight line because their pseudopods are formed slightly off-center, causing them to go to the left or right. Several long filamentous bacteria can be seen nearby.

Sampling Date : 22 September 2006

Sampling Site : KASHIMADAI paddy field  Google Map