Plumatella fruticosa has horseshoe shaped polyps that extend from the top of each zooid.

This enlargement clearly shows the horseshoe shapeof the Plumatella fruticosa polyp with a double row of tentacles. Also the mouth is clearly visible.

This picture provides a more detailed view of a polyp. The structure that strengthens the base of the polyp and bares the tentacles can be clearly seen.

This picture provides yet another view on a polyp.

P. fruticosa appears also to have a thin tissue layer around the base of the tentacles. Possibly it serves to protect the tentacles whent the polyp is retracted, possibly it is spare skin to enable retraction. It is also possible that it has an important influence on the water stream and improves the chances to catch food.

A side view of the base of the polyp. Again the tentacle baring structure can be clearly seen.

The next 5 pictures show the excretion of a faeces (excrement) package. They are selected from pictures of several zooids to show the various stages most clearly.
The first picture shows the faeces package still in the body cavity of a zooid.

The second picture shows a detail of a package that barely extends beyond the anus.

The third picture shows a package halfway extended through the anus. It is very clear that the anus is outside the polyp.

The next picture is a few seconds later - the faeces package is almost out.

The last picture shows the package fully excreted.

This picture shows statoblasts inside a zooid body cavity.

The next two pictures show how statoblasts develop in a row of increasing maturity, the youngest is deepest in the zooid body cavity.

And this picture provides a detailed image of a full grown statoblast in the body cavity of a zooid.

The following series of pictures shows retraction and extention of a polyp. The freedom of movement in multiple directions can be clearly seen. Also the zooid end part extrend, contracts and changes direction during the process. For P. fruticosa the whole process happens within a minute.

The next series of pictures shows the same process for a different zooid. Again the whole process happens within a minute.

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 1.5 MB in size. Playing across a slow internet link may take a lot of time.

(click on the photo to start the video)

	The first video (2,9 MB) shows a Plumatella fruticosa polyp during normal activities. the polyp moves back and forth and tentacles move also.
	The second video (5,7 MB) shows two Plumatella fruticosa polyps that extend.
	The third video (8,6 MB) shows a P. fruticosa polyp that struggles with a faeces package. It is very clear that the anus is outside the polyp. What amazes me is how much space is available adjecent to the polyp in the zooid wall enclosure and how flexible the zooid wall is.