Victorella pavida through a microscope

Verder in Nederlands

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Victorella pavida has polyps that are different from all other fresh water species: round and only 8 tentacles.

Victorella pavida microscope

Observed in more detail it is easy to see the common base tube (stolon) on the upper side of the photo, from which the zooids stick out. The stolon grows crawling across the substrate
The small extensions that can be seen sticking out from the zooids are ciliates that grow there, not part of the Victorella zooids.

Victorella pavida detail

Seen in even more detail Victorella pavida's internal structures become apparent, specially the stomach-gut system. The esophagus (top) is closely behind the mouth in the middle of the tentacle crown, while the end-gut ends outside the polyp (below).
Also can be seen that V. pavida has a fold in the body wall to allow retraction and extension of the polyp. This fold can be seen as a ring-shape behind/below the esophagus.

Victorella pavida more detail

The next photo provides a view of the mouth of a V. pavida polyp.

Victorella pavida detail

This photo provides a different view of a V. pavida zooide. Here stomach and gut (greenish) can be easily seen.

Victorella pavida detail

V. pavida polyps are fairly distant from each other, as compared to many other freshwater bryozoans.
The photo also shows how agile the V. pavida tentacles are.

Victorella pavida multiple zooids

The next photo provides yet another side view.

Victorella pavida side view

Sometimes a zooid grows on another one. Both zooids have retracted their polyps. I chose this photo over one with the polyps extended as it shows the intended information in a better way.

Victorella pavida zooid on zooid

Video through a microscope

The videos below are in WMV format and require a compatible player, such as windows media player, to view.
The video is 60 seconds and 2.2 MB in size. Playing across a slow internet link may take a lot of time.

(click on the photo to start the video)

video V. pavida
This video shows normal behavior of some V. pavida zooids.
One of the zooids extends shortly after the video starts. The other polyp attempts to capture something by bending the tentacles. It is amazing how mobile the zooids are.
video V. pavida
This video again shows normal behavior of some V. pavida zooids.
One of the zooids retracts the polyp and is clearly busy with something as it takes a while before it reappears. This is often much faster (my observation) Once the polyp starts extending, the process is rapid.