H. punctata is named 'punctata' as the zooid often is spotted, as can be seen on this photo. It is also clear that the polyp opening is relatively wide and that the zooid is 'ringed' or at least does not run down in a straight line to the base.

The second photo clearly shows the unevenness of the zooid wall as well as the wide zooid opening; much different from for example Plumatella repens.

To make this point even more clear H. punctata and P. repens are shown side by side. In the field it is easily possible to confuse both species.

H. punctata	P. repens

The next photo shows the polyp base.

An enlargement clearly shows the structure that 'protects' the mouth, or maybe helps making catching food more effective by forming a sort of trap. The structure is also called 'epistome'.

The next photo shows what the cystid opening looks like when the polyp is retracted. The way the tentacles are retracted can be clearly seen. On the base of the zooid a new zooid seems to be forming.

This photo shows the zooid opening in even more detail. The tips of the tentacles (retracted) are just visible.

The next photo shows a see-through of a zooid. The mouth and esophagus can be clearly seen. It is surprising how far the polyp extends from the zooid opening. To the left side the retractor muscle can be seen that retracts the polyp into the zooid cavity.

In another see-through photo it can be clearly seen how the zooid wall is folded to enable extending and retracting the polyp. Also the epistome can be clearly seen.
Besides that the photo shows some kind of protection cap on the upper side of the polyp stem.
Finally the for Hyalinella typical rippled outer wall is well illustrated.
The lower zooid seems to have a faeces (poop) particle in the lower gut that is on its way to be expelled.

This photo shows yet another cross section with all former mentioned structures present again.

The final photo shows statoblasts clearly visible in the zooid cavity.

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 shows normal behavior of a zooid. It is amazing how flexible a zooid is and how active the polyp is moved around in search for more food.
	The second video shows how active the digestive tract is. Movement os nearly continuous. There are two zooids, an older one and a younger one, judging by appearance. Both show healthy gut movement.