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Many protists move by means of flagella. A flagellum is a long whip
like structure made from assemblages of microtubules. Flagella typically
are long relative to the size of the cell, compared to cilia which often
are quite short. The flagellated Protists are placed in a number of Phyla
which are not at this time well defined.
|The Euglenida include Euglena and other photosynthetic flagellates. These flagellates usually have chloroplasts as do plants. Howvever, unlike plants they do not have a cellulose cell wall. Instead the they are surrounded by a protein pellicle. The first picture shows a common flattened Euglenid called Phacus. This flagellate is common in the warm ponds of summer in Kansas. Euglenids also typically have a red pigmented areat for detecting light.|
flagellates do not have chloroplasts or a protein pellicle and thus are
considered to be more animal-like. These flagellates are often put in the
phylum Zoomastigophora or Zoomastigina. They include a number of colonial
forms such as this unidentified freshwater zoomastig. This colonial organism
belongs to a group of flagellates called choanocytes. Each cell has a special
collar with a flagellum originating on the cell and going through the opening
of the collar. The beating of the flagellum sets up currents which sweep
water and small organisms into the collar where they become trapped in
contractle fibers in the collar. These flagellates then are filter feeders.
relationships between these creatures and other organisms are quite diverse.
Some zoomastigina cause important human diseases. Trypanosomes cause sleeping
sickness and Chagas disease while the well known water borne disease giardiasis
is cause by an organism in the genus Giardia. One of th most famous
relationships involves that between many termites and zoomastigs in the
termite gut. The termite injests the wood and the gut microorganisms, including
the zoomastigs, digest the cellulose forming sugars and acetate. The acetate
is taken up by the termite gut and serves as an energy source for the termite.
The large multiflagellated Trichonympha shown here is a common intestinal
flagellate of termites.
pgd revised 2/17/01