Stentor (sten-torr) is a genus of large, trumpet-shaped ciliates, commonly found in freshwater ponds, frequently attached with the posterior end to vegetation or other surfaces. Detached individuals swim freely and adopt an oval to pyriform shape. There is a well-developed peristomial field with a system of adoral membranelles (AZM) at the anterior end, and the AZM spirals clockwise to the cytostome. The cilia of the membranelles are much longer than the somatic cilia. The macronuclei of Stentor may be spherical, elongate, a long thread, or formed like a string of pearls. There is a single contractile vacuole with two collecting canals near the cytostome. Some species of the genus build transparent lorica of secreted mucus. The cells can be intensive coloured by pigmentation granules located in the pellicula (green, pink, blue, orange or violet). Stentor amethystinus can be coloured brownish, violet or purple red. The cell has symbiotic algae. This specimen was collected in freshwater ponds near Konstanz, Germany. Differential interference contrast. This picture was taken by Martin Kreutz using an Olympus microscope. Image copyright: Martin Kreutz, image used under license to MBL (micro*scope).
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From the collection
Freshwater ponds of Konstanz (Germany)
|Description of Stentor amethystinus: Extended cells 250-500 microns long, contracted cells 135-350 microns. In the center of the body more spherical macronucleus (in vivo 20-30 microns long) with many (>20) micronuclei. Cells look brown, with red pigment granules and green symbiotic algae. Contractile vacuole at the left wall of the mouth funnel. 90-110 longitudinal ciliary rows, the gap between which becomes larger in the clockwise direction. Peristomial region with 20-25 ciliary rows. About 200-300 adoral membranelles. Parallel to the adoral membrane zone. Common. |