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A strange organism near particles

A round organism with a brown center slowly moves along the edges of particles. It looks like Helizoa, but the axopods are arranged differently, and the brown center is not characteristic of Helizoa. Who is this organism? Sometimes we encounter strangers in our journey through the microscopic world.

Commentary by Prof. Yuji Tsukii, Hosei University
This organism belongs to genus Diplophrys in the group of Granuloreticulosea.

The features of this genus are: 1) When it moves, fibrous pseudopodia radiate from both sides of the cell, and 2) A large droplet that looks like oil is included in the cytoplasm. 3) The whole body is covered by a very thin shell that is not visible with an ordinary microscope. Amoeba belonging to genus Amphitrema exhibit similar features. But in the case of Amphitrema, sand particles are attached to the shell, and a variety of symbiotic algae are included in the cytoplasm.

Amphitrema is found only in high-altitude wetlands.

Sampling Date : 08 August 2009

Sampling Site : Hirose River A  Google Map

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