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Portrait of Didinium nasutum, a barrel-shape haptorid ciliate with a conical anterior snout containing prominent extrusomes. Two ciliary girdles. Oral aperture forms anteriorly at the apex of the snout. Two ciliary girdles, one circumoral and the other equatorial . Posterior contractile vacuole. Macronucleus C-shaped or oblong. Fast swimmer. Fixes prey (often Paramecium or Frontonia) with nontoxic extrusomes called pexicysts and kills them with toxicysts before engulfing them whole through enormously extensible oral aperture.Didinium may be confused with early dividing individuals of Monodinium. From freshwater pond with abundant Frontonia near Boise, Idaho.
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in vivo portrait of the pleurostomatid ciliate, Amphileptus pleurosigma (Stokes,1884) Foissner, 1984. DIC.
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The green arrow indicates a uniform subpellicular layer of globular structures,probably mitochondria.The yellow arrow indicates the posterior end of the slit-like oral aperture.The pink arrow indicates the right perioral kinety.
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Didinium (die-din-ee-um) nasutum is an oval ciliate ranging in size from 80 microns to 200 microns, but is usually 120 - 150 microns long. This ciliate lives in freshwater habitats and is frequently seen in pond samples. It has two conspicuous bands or girdles of cilia (pectinellae); one round the front pointed end and one band just below the middle of the cell. The oral dome at the anterior end extends as a snout or nose. This feature gives it its species name, 'nasutum' - meaning 'nose'. Didinium can easily be confused with dividing cells of a similar genus with only one anterior girdle but formed a second girdle in the mid-body during cell division. This is a slightly squashed specimen. The lateral view shows the two ciliary girdles and the oral dome equipped with hundreds of extrusomes. The cell is 126 X 108 microns. Differential interference contrast.
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The yellow arrow indicates the micronucleus in a membranous envelope between the two granular macroniclei. DIC.
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Didinium (die-din-ee-um) nasutum is an oval ciliate ranging in size from 80 microns to 200 microns, but is usually 120 - 150 microns long. This ciliate lives in freshwater habitats and is frequently seen in pond samples. It has two conspicuous bands or girdles of cilia (pectinellae); one round the front pointed end and one band just below the middle of the cell. The oral dome at the anterior end extends as a snout or nose. This feature gives it its species name, 'nasutum' - meaning 'nose'. Didinium can easily be confused with dividing cells of a similar genus with only one anterior girdle but formed a second girdle in the mid-body during cell division. This slightly squashed specimen was collected in the plankton from Lake Constance, Germany. The image is in focus on the two ciliary girdles. Cell - 126 X 108 ¦m. Differential interference contrast.
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The undischarged extrusomes (yellow arrow) are plentiful in the cytoplasm. They are 10-15 µm long,slender,curved with a small bulbar enlargement at one end. This is seen only with DIC. There is a small cluster of extrusomes at the anterior cell apex.
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Portrait of Didinium nasutum (Mueller,1773) Stein, 1859, a barrel-shape haptorid ciliate with a conical anterior snout containing prominent extrusomes (seen well in this image). Two ciliary girdles. Oral aperture forms anteriorly at the apex of the snout. Two ciliary girdles, one circumoral and the other equatorial (not well-seen in this image). Posterior contractile vacuole. Macronucleus C-shaped or oblong. Fast swimmer. Fixes prey (often Paramecium or Frontonia) with nontoxic extrusomes called pexicysts and kills them with toxicysts before engulfing them whole through enormously extensible oral aperture.Didinium may be confused with early dividing individuals of Monodinium. From freshwater pond with abundant Frontonia near Boise, Idaho. DIC.
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The discharged extrusomes have a long thread-like extension (black arrow).Stained by the silver carbonate technique (see Foissner, W.Europ. J. Protistol.27:313-330;1991).Brightfield.
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A somewhat compressed but living individual of this ciliate. Only the anterior of the two bands of cilia are evident. the extrusomes in the anterior mouth are used to capture prey.
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The discharged extrusomes have a long thread-like extension.Stained by the silver carbonate technic (see Foissner, W.Europ. J. Protistol.27:313-330;1991).Brightfield.
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A view of the cytopharynx but in a dividing Didinium. This cytopharynx is in the proter (anterior) daughter cell. The lamellae, each consisting of a set of perpendicularly arranged microtubules (mt), cover this food-vacuole forming region. Vesicles (ves) lie near the cytopharyngeal membrane and fuse with the membrane (arrows). EM taken on 5/20/69 by R. Allen with Philips 300 TEM. Neg. 6,370X. Bar = 1 micron.
This image is available in Richard Allen's collection.
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There are 25-35 right somatic kineties that converge anteriorly on a suture. There are 4-6 dorsal rows of bristle-like cilia. There is a single row of short cilia forming the dorsal brush.DIC.
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Portrait of large haptorid ciliate Homalozoon vermiculare (STOKES,1887)STOKES,1890. Laterally flattened. Bluntly rounded anteriorly and tapered posteriorly. Contractile. Slit-like oral aperture with prominent oral bulge extrusomes. Multiple small contractile vacuoles along lateral margin. Macronucleus moniliform. Brightfield. From standing freshwater with abundant decomposing leaves near Boise, Idaho.
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Portrait of Monodinium. Haptorid ciliate with single circumferential ring of cilia anteriorly. Prominent proboscis with extrusomes. Contractile vacuole posterior. Swims very rapidly rotating on long axis. From freshwater pond near Boise, Idaho. Brightfield.
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Detail of anterior of Homalozoon vermiculare (STOKES,1887) STOKES,1890 showing dense collection of oral bulge extrusomes. The characteristic dense anterior aggregate of pharyngeal granules is well seen. The function of these is unclear. Brightfield. From freshwater pond near Boise, Idaho.
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Portrait of Actinobolina, a haptorid ciliate with retractile tentacles spaced at intervals along longitudinal uniform ciliary rows. Oval in shape with small apical anterior oral aperture. Tentacles retract during swimming and elongate dramatically when resting. Each tentacle bears a long cylindrical toxicyst at its end. Tentacles are not knobbed as in many Suctoria. Prey are paralyzed by toxicysts then manoeuvered to the oral aperture for ingestion. Several species some with Zoochlorellae. This individual has just come to rest with tentacles beginning to extend. From freshwater pond near Boise, Idaho. Phase contrast.
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Homalozoon vermiculare (STOKES,1887) STOKES,1890 seen here preying on a peritrich ciliate. The characteristic dense aggregate of granules can be seen. This is displaced by the ingested prey and then disperses as the food vacuole proceeds distally. From freshwater pond near Boise, Idaho. Brightfield
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Portrait of Actinobolina radians (Stein, 1852).Collected from afreshwater pond near Boise, Idaho (43°37'04.05" N;116°11'06.99" W).DIC.
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This cell has been killed and then stained with Feulgen stain which shows up the nuclei. As with all ciliates, there are two kinds of nuclei, a large macronucleus which takes the form of a string of beads, and smaller micronuclei which in this species are numerous small structures located near the macronucleus.
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Trachelius (trach-eel-ee-us) is a predatory ciliate with a short projecting snout, and with the mouth located at the base of the snout. Cells usually look much slimmer than this cell which has recently had a meal. Cytoplasm very vacuolate. Phase contrast.
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Phase contrast micrograph of a living cell. The line of contractile vacuoles, lines of the kineties and the band of extrusomes just under the mouth are visible.