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Updated 3.1.2021

Single-celled organisms - old acquaintances

Some unicellular organisms are probably familiar to everyone from their school days, including the slipper animal Paramecium caudatum and the eye animal Euglena spec.

However, some species are particularly small or so inconspicuous that they are easily overlooked...

Perfectly adapted blue-green algae eaters: ciliates of the genus Nassula. The nassulid ciliates have a special cage-shaped mouth organ, with which they can ingest filamentous cyanobacteria at enormous speed and even bite off the algal filament enzymatically. The clips shown here are not time-lapse, but shot at normal speed..

Peranema are small flagellates in size from 20-70µm in diameter. They are very active predators and scavengers. Peranerma is common in waters rich in organic nutrients, especially in water in which decay is taking place. The single flagellum projects straight forward, and a rapid rotation of its extreme end pulls the Peranema smoothly through the water. The body of the Peranema can undergo extreme contraction and distortion as it moves.

This is a tiny, little amoeba, Diplophrys archeri, frequently found in Sphagnum habitats.

Zoothamnium sp. Colony. These are tiny little peritrich Ciliates, often found on submersed plants. Can you spot the many Mitochondria on the stalk muscles, these are the little power stations for the retraction muscles.

This is Paramecium bursaria, a common ciliate in freshwater habitats. It contains hundreds of symbiotic green alga cells genus Chlorella. I frequently have been observing these wonderful ciliates over the last years and in all samples the animals had more than one expulsion pore for each of the two contractile vacuoles. In this clip the individual has two expulsion pores for each CV, clearly visible. It would be very interesting if anyone out there had similar finds, please let me know !

Euglena algal cells in movement. There is a very thin water film between slide and coverslip to show all the details of the cells, so the cells show the typical euglenoid movement. Watching euglenoid cells at higher magnification is always fun, you can see all the cell compartments including the huge nucleus with a grainy structure, the many paramylon grains with the characteristic oval shape, the red eyespot, the flagellum, the flagellar pocket with the contractile vacuole, the relatively big chloroplasts and at least the wonderful euglenoid pellicle, composed of parallel ribbonlike strips.

This tiny rotifer belongs to the Lepadella species and can be found widespread in many aquatic habitats. It is specialized in feeding on biofilms growing on submersed plants and benthic areas.

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