Shelled Amoeba

For millions of years, animals have adapted to dangerous environmental conditions and developed various defense systems against predators and adverse factors. Some species excel in camouflage, others produce toxins. Many are quick, while some build protective fortifications. In the fluffy aquarium moss, simple microorganisms reside, skillfully using organic and mineral particles to create their own protective shelters or shells.

Appearance & locomotion

Testate amoebae represent a unique class of unicellular microorganisms that got their name thanks to the presence of a shell. This miniature shell serves as a unique form of protection and is an important characteristic for their classification. The shell of the amoeba Arcella discoides has a golden-brown color and a disk-shaped form with a central opening, through which the amoeba interacts with the environment. The depressions and spines on the shell of Centropyxis aculeata give it sharpness and geometric complexity. The shell of Euglypha filifera has an elongated shape, resembling a narrow vessel. It looks like a miniature amphora or bottle with a faceted structure and sharp protrusions. The shell of Difflugia corona is named after its crown-like shape full of protrusions and depressions of the surface. The multi-toothed opening further adorns its shell. The movement of testate amoebae is carried out thanks to thin pseudopodia protruding through the opening in the shell. However, their movement speed is extremely low. To study amoeboid movement in detail, the use of a timelapse mode during video recording is required.

Feeding, reproduction & their role in the aquarium

Testate amoebae feed on bacteria, microorganisms, algae, and organic remnants, capturing them with the help of pseudopodia extending from the shell. The reproduction process of testate amoebae can occur both sexually and asexually. In asexual reproduction, the cell divides into two parts, whereof one remains in the shell and the other builds its own shelter.

Testate amoebae demonstrate a high degree of adaptation to various environmental conditions.
By going into anabiosis, they can withstand extreme conditions, including freezing. As of today, science has identified approximately 1500 species of these primitive organisms, which inhabit not only freshwater reservoirs but also moist soils and mosses. They play a significant role in ecosystems, participating in the decomposition of organic matter and the cycling of substances.

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