Litostomatea

A Litostomatea a csillósok osztálya. 3 alosztálya a Haptoria, a Trichostomatia és a Rhynchostomatia. A Haptoria tagjai, például a Didinium elsősorban ragadozók, egy Didinium-faj például Paramecium fajokat eszik. A Trichostomatia jobbára endobionta, ide tartozik például az egyetlen ismert humán patogén csillós, a Balantidium coli. A Rhynchostomatida 2, korábban a Haptoriába sorolt, de genetikailag tőlük megkülönböztethető szabadon élő rendet tartalmaz, ezek a Dileptida és a Tracheliida.

Morfológia

In litostomes, the body cilia arise from structures in the cell cortex called monokinetids, which are made up of a single cilium and its associated structures, such as basal bodies and microtubular fibres. These have an ultrastructural arrangement characteristic to the group.

The cell "mouth" (cytostome) is apical or subapical. In trichostomes it lies in a depression, or vestibule, containing modified somatic cilia. In one order, the Entodiniomorphida, the cilia are arranged into tufts or bands, and may be packed together to form syncilia, resembling the membranelles and cirri of spirotrichs (with which they were originally classified) and other ciliates. However, no true compound cilia occur.

In haptorians the mouth is typically surrounded by a ring of coronal cilia, arising from dikinetids derived from the anterior of the body kineties, and a ring of characteristic extrusomes called toxicysts. These discharge on contact with prey, penetrating and immobilizing them, and beginning digestion. In some forms the mouth is formed only during feeding, and everts to assist in capture. The cytopharynx takes the form of a straight tube, supported by rods or nematodesmata, which dilates greatly during ingestion. This structure is called a rhabdos, and is functionally and structurally distinct from the cyrtos found in several other classes.