Detail of ejected extrusome of the hymenostome ciliate, Frontonia acuminata (EHRENBERG,1833) BUETSCHLI,1889. Numerous extrusomes form a peripheral fringe. The ejected extrusomes of this genus have a distinctive hook-shaped distal end. Collected from a slow-moving freshwater stream near Boise, Idaho in July 2003. DIC optics. This image was taken by William Bourland. He now uses a Zeiss Axioskop 2 with Spot Insight and Spot Flex CCD cameras (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
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From the collection
Freshwater and Terrestrial Microbes of Idaho (USA) and Elsewhere
|Description of Frontonia acuminata: Species in this genus of ciliates range from 60 to 300 microns long. The cell is ovoid with an oral depression in the anterior half of the cell. The cell may be dorso-venterally flattened and may have a pointed posterior. The oral aperture is located at the bottom of this depression. The oral structures are difficult to see without silver staining the cell: on the right of the depression there is a undulating membrane and on left there are three membranelles. Regular somatic ciliation covers the entire cell, with cilia ~10 mm long. Trichocysts occur regularly at the cell surface. Typically one, but possibly two or many contractile vacuoles occur; these may have radiating canals. The macronucleus is ovoid to reniform and centrally located. Habitat and distribution: benthic; plankton; freshwater, marine, common. |