Trichodina

Name

Greek: trix, trichos = fine hair, dinos = unregular.

Classification

Genus of the subphylum Ciliophora (belonging to the protozoan phylum Alveolata)‐classis: Oligohymenophorea, order: Mobilida.

Morphology

Species of the genera Trichodina (Ø 60 μm), Trichodinella (Ø 40–50 μm), Tripartiella (Ø 40 μm), etc., live as ectoparasites on the skin and/or gills of many fresh and saltwater fish, but also on hydrozoan or anthozoan polyps (e.g., T. pediculus = louse of polyps). The trophozoites look like a depressed cylinder and show bunches and rows of cilia at both sides. At the ventral side they develop species‐specific circles of hooks, which are used as holdfast organs to become attached at the surface of their hosts, where they move in slight rotations (Figs. 1– 3, pages 1471, 1472). At high infection rates (in mass productions of fish or on fish with other diseases) the symptoms of trichodinosis may become severe. Flagella.

Figure 1

LM of the ventral anchor-apparatus of the trophozoite.