below photos have been taken in September 2016, water samples taken from a plant inside a koi pond. According to Wikipedia, this is Pistia stratiotes, a floating plant found worldwide in tropical and subtropical waters:
Pistia stratiotes im garden pond
Quelle: Wikipedia
Foto: Kristjan
During November, I took a closer look at the root of this floating plant under a stereo microscope: The roots were colonized by various, case-building rotifers, but soon my interest turned to the Platycola decumbens, also called known as "Wärmflaschentierchen" (translation from german could be maybe "hot-water bottle animal"), which settle there in great numbers.
I transferred a root shoot of the water lettuce into a 1 mm thick "chamber" in order to view and document it a bit more closely under the Zeiss IM35 inverted microscope on two consecutive weekends.
Due to the thickness of the chamber the conditions for a photo documentation were not optimal, the one or other somewhat dull-looking photo can be probably attributed to it. But the cute creatures were allowed to stretch without "pressure".
I hope that the one or the other photo will provide some interesting details.
General view of a Platycola population on a root of Pistia stratiotes. On the subastrate there are numerous housings, a lot of the dwellings are empty and no longer inhabited by the zooids. Due to the dark coloration, the elliptical outline of the shells appears clearly differentiated against the background of the substrate.
Other section of the root, the focus was chosen to show some of the platicola in lateral view. A "serrated crown" also made it into the overview image.
The entire back of the case rests on the substrate. In the lateral view, the collar of the case appears to be erect at 45°. The top of the case is distinctly rounded, while the underside is flat. The body shape of the fully extended zooids is almost cylindrical, somewhat tapered towards the posterior end.
Following photo shows two individuals which have retracted into the case, the outline of the case is somewhat irregular or abnormal. The photo on the right clearly shows the dark brown colored adhesive fringe on the edge of the case.
The coverslip was also colonized by an individual. This allowed a slightly more detailed view of the zooid: the fine striation of the zooid can be clearly seen, with the end of the cell attached to the edge of the case.
The optical section of the photos on the right shows the peristrome of the zooid.
The macronucleus is elongated (left image), next to it more details of the mouth area.
Finally, two photos of squatters who have made themselves comfortable in the vacant housing.
Unfortunately I don't have any photos which show the development cycle of the hot-water bottle animal. But maybe someone has interesting shots to show?
Literature:
Schneider, Prof. Dr. Heinz: Bilder aus dem Leben des „Wärmflaschentierchens“ Platycola Truncata. Mikrokosmos 72. 289 - 295
(http://www.zobodat.at/pdf/Mikrokosmos_72_0001.pdf)
