P. articulata has a round polyp that sticks out sideways from the zooid, through a small rise in the wall, as can be seen well in this photo made through a microscope. The structures that can be seen inside the zooid are partly the esophagus and the gut and partly the retractor muscle that is used to retract the polyp inside the body cavity.
The zooid wall is covered with algae and ciliates.

The next picture shows a zooid with a retracted polyp, making the entrance the polyp extends through clearly visible.

This picture shows the same zooid as the previous picture, but now the polyp starts to extend and sticks out partially.

This picture shows a fully extended polyp.

This picture clearly shows the septum that divides two zooids.

The next picture shows the best image i could make of a hybernacula, the P. articulata survival capsule. The hybernacula, also called 'brown body', is fairly thick, making it impossible to show all parts at the same time.

This picture shows a young developing zooid. The internal organs can be clearly seen.

The last picture shows another young zooid. At the apex a septum has developed and a new zooid is in its initial stages of development on top of that.

Video through a microscope

The videos below are in WMV format and require a compatible player, such as windows media player, to view.
Each video is 30 to 60 seconds and of significant size. Playing across a slow internet link may take a lot of time.

(click on the photo to start the video)

	The first video (8,5 MB) shows a Paludicella articulata polyp during normal activities. The polyp moves around and the gut shows peristaltic movements. I did not know that food is taken in using an active suction movement of the mouth. These movements can be clearly seen. Once or twice the suction was a success and some particle is swallowed.
	The second short video (1,5 MB) shows eating behavior - suck and swallow.
	The third video (8,5 MB) shows a sequel to the previous one. I did not realize that a polyp is so active. The naked eye only shows major movements, such as retracting or extending the polyp.
	The last video (2 MB) shows the movements of the internal organism in greater magnification.