world of amoeboid organisms


Observations on a specimen of Arboramoeba reticulata

On August 20 2015 I took a sample from sediment on the bottom of a shallow stream in the garden of the former royal palace ‘t Loo in the Netherlands. The stream is oligotrophic. At home I made some wet mounts with cover slips 18 X 24 mm and kept them in a moisture chamber. The mounts were examined regularly, but not dayly. Evaporated water was supplemented with rainwater by means of an injection needle.

Day 2: In one mount I found this large belt-shaped amoeboid with both ends hidden in a piece of debris. The cell was up to 600 µm long. It was the only large amoeboid in the mount.
Day 6: There was one large tree shaped network, surrounded by a large number of small algae or blue algae which were consumed by the amoeboid. The size of the total network was c. 600 µm. I believe this one was the belt shaped one which I observed before (stacked image).
Day 7, 23:57: One part has detached itself from the main mass, thus becoming a new cell. Just like the main cell it didn’t quite move.
Day 8, 12:31: This photomicrograph was taken 12 hours after the previous one. It seems that a second specimen from the main mass has joined the other one.
Day 9: starts with the photomicrograph above and below:
The lower branch is up to 1.8 mm
Day 10:
The middle part of the pseudopodium has disappeared, maybe eaten by a rotifer or…? Remarkable is that the original part also disappeared (arrowed) but was restored later.
on = original network; r = restored part; nc = new cell, which stayed here for three days without any significant locomotion.
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