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Amoeba from a paddy field

The sample was observed immediately after being collected from a paddy field.

As the body of this amoeba is completely transparent, it is difficult to find it among the surrounding aggregates.


Commentary by Prof. Yuji Tsukii, Hosei University
This organism is a kind of naked amoeba. To identify naked amoebae, it is necessary to know how they move. In this video, the surrounding aggregates block the view of the whole cell, which makes identification difficult.

It can be guessed from the video that the cell may be more than 100μm long and not quite flat, so this amoeba may belong to the suborder Tubulina.

At the top of the cell there is a transparent part without particles, called a hyaline cap. It is unusual that, in spite of its large size, this cell contains relatively few large particles. Usually a large amoeba has many more small particles.

Is this amoeba really a large type and is the scale of this video correct?

Sampling Date : 17 August 2006

Sampling Site : KASHIMADAI paddy field  Google Map

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.

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

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

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

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