Stentor, the trumpet animalcule, is a single‐celled organism (protist) belonging to the ciliates (Ciliophora). It is interesting because of its trumpet shape, commonness, comparatively large size (∼1 mm), attractive coloration and high regeneration capacity.

Keywords: ecology; learning; ciliates; regeneration; bioassay

Figure 1.

A Stentor assemblage showing the main shape and macronucleus types (from Curds et al., modified). (a) Large (1–4 mm), slenderly trumpet‐shaped species with a vermiform and a moniliform macronucleus, respectively. (b) Freely motile, turbinate specimen with coloured pigment stripes. (c) Small to medium‐sized (100–1000 μm), broadly trumpet‐shaped species with single, spherical macronucleus. (d) Campanulate species.

Figure 2.

An almost fully extended Stentor niger adhering to the microscope slide (courtesy of M. Kreutz, Germany). This beautiful species is up to 1 mm long, has a single globular macronucleus (MA), and is yellow‐brown due to brownish pigment granules. Note the mighty adoral zone of membranelles (AZM), which swirls food particles into the huge buccal cavity (BC). AZM, adoral zone of membranelles; BC, buccal cavity; CR, ciliary rows; CV, contractile vacuole; FV, food vacuole; L, lorica; MA, macronucleus; PB, peristomial bottom; PS, pigment stripes; SC, sensory cilia.

Figure 3.

Stentor multiformis (a, d) and S. amethystinus (b, c), both slightly squashed to show details of the organization (courtesy of M. Kreutz and P. Mayer, Germany). S. multiformis is a small species (length about 250 μm when fully extended) with beautiful blue pigment stripes and a single globular macronucleus. The individual pigment granules are blue and about 1 μm across. The narrow white zones between the pigment stripes contain the ciliary rows. S. amethystinus is a medium‐sized species (up to 500 μm long when fully extended), which appears dark at low magnification due to the lilac pigment stripes and the symbiotic green algae. This species often blooms in the pelagial of small lakes and ponds. AZM, adoral zone of membranelles; FV, food vacuoles; MA, macronucleus; PS, pigment stripes; SA, symbiotic green algae.



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Further Reading

Grain J (1968) Les systèmes fibrillaires chez Stentor igneus Ehrenberg et Spirostomum ambiguum Ehrenberg. Protistologica 4: 27–35.

Grain J (1986) The cytoskeleton in protists: nature, structure, and functions. International Review of Cytology 104: 153–249.

Pelvat B (1985) Observations sur l'ultrastructure de l'appareil buccal chez le cilié hétérotriche Stentor coeruleus. Protistologica 21: 61–80.

Randall JT and Fitton Jackson S (1958) Fine structure and function in Stentor polymorphus. Journal of Biophysical and Biochemical Cytology 4: 807–830.

Tartar V (1970) Transplantation in Protozoa. Transplantation Proceedings 2: 183–190.

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Foissner, Wilhelm(Apr 2001) Stentor. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001971]