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.
Many
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.
The
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