Stentor (sten-torr) is a genus of large, trumpet-shaped ciliates, commonly found in freshwater ponds, usually attached with the posterior end to vegetation or other surfaces. Detached individuals may swim freely and adopt an oval to pyriform shape. At the anterior end of the cells a conspicuous peristomial field with a system of adoral membranelles spiralling clockwise to the cytostome. The cilia of the membranelles are much longer than the somatic cilia. The macronuclei of Stentor may be spherical, elongate to a long strand or formed like a string of pearls. There is a single contractile vacuole with two collecting canals near the cytostome. Some species build transparent loricas of secreted mucus. The cells can be intensive coloured by pigmentation granules located in the pellicula (green, pink, blue, orange or violet). This group of Stentor coeruleus was collected in freshwater ponds near Konstanz, Germany. This species is couloured blueish and the macronucleus is like a string of pearls. 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 coeruleus: Blue heterotrich ciliates, body large, the width of the anterior extremity or peristomal border when fully extended equal to one-third of the total length. The substance of the intermuscular longitudinal striae coloured a more or less intense blue. The fine ciliary clothing of the general surface of the integument occasionally supplemented with a few long, fine cilia, which are not, however, conspicuously developed. Nucleus transparent, moniliform. Length 132-265 microns. |