This is the first picture ever in the Netherlands of P. magnifica.
The yellowy color is caused by the brownish peatwater of the stream it was living in. The depth of sight was about 25 cm when the picture was taken.
This colony lived below a bridge at a depth of about 20 cm and was about 15 cm in diameter.
The first impression, never having seen P. magnifica before, was of a closly packed group of C. mucedo colonies. A second look proved this wrong.
A more thorough search of the bridge showed 10 colonies, including one that grew on a steal boat moored below the bridge. No colonies grew on wooden mooringpoles downstream of the bridge. No colonies grew on the upstream 1/3 of the bridge.
On other structures near the bridge more colonies could be found. Some were up to a square meter in size.
P. maginfica typically organizes its zooids in 'rosettes'.
The pictures taken in-situ show that the first impression of a colony is white. This is caused by the massive number of large polyps that are extended and cover the gelatinous colony central mass.
Pictures taken above water show a brouwnish colony. See for example: Bryozoans from the Connecticut rivier, or this site elsewhere in Amerika or these pictures on the same site.
In another place nearby i also found large P. magnifica colonies. The white points are casued by retraction of some polyps. In bad visibility situations it is necessary to position the photocamera very close to the colony in order to have a usable picture. This easily causes disturbances that in turn cause polyps to retract.
This picture is a cutout of a detail picture and shows one 'roset' in detail.
This picture is a more extreme enlargement and shows a few polyps.
Notice the special shape of the tentacles at the end of the polyp.
After some trying i have convinced some polyps to retract. This is how that looks.
The extreme macro lens has a very limited region of sharpness.
This colony clearly makes statoblasts. This cutout shows them.
This colony was dying off. Whitisch transparant colony rests remained. In the still more or less intact part of the colony the transparent gelatinous colony body can be clearly seen.
This colony was also dying off en shows statoblasts on large parts of the surface. This colony was no longer active. The picture was taken on October 14 2005, that is a few weeks later than the pictures above.
Thanks to the dying colonies statoblasts are freed. Some remain in the immediate vicinity.
This picture was made at the side of a ponton. The nearest colony was about 10 cm down.
This picture, made on the same day, shows a colony that is partially active. More colonies were in this state at that place and time.
The picture below is taken a bit earlier in time and shows statoblasts inside the colony, partly thanks to several retracted polyps.
Early june 2006 i went back to see how P. magnifica was doing. The water temperature was 21° Celcius. There were colonies in various states of development. The cut-out below shows the smallest colony i found. Sorry for not being completely sharp - this is at the edge of what this camera can do.
I was surprised to see the variation in colony maturity. In some places hand-sized colonies existed. Nearby much smaller colonies could be found and i also found several statoblasts that had not yet developed. Apparently P. magnifica has a strategy of spreading statoblast development over a period of time.
Sometimes P. magnifica grows around an object like a rope or as here a branch. It will then form more or less ball shaped (donut shaped) colonies.
This photo comes from the Piepertkolk in Zwartsluis. Visibility was not very good with a lot of algae in the water.
A find in a pond in Tilburg was photographed by Mr. H. Hamers and is used here with his kind permission.
This is what a P. magnifica colony looks like out of the water. The rosettes formed by the zooids can clearly be seen at the upper side. The size of the jelly like colony base is impressive if you think about a few hundred 6 mm animals producing it.