New or special finds
Last modification: 27-12-2009
During a cold wintery dive in the Veenmeer (Tynaarlo, NL) i found more than 10 Cristatella mucedo colonies with their polyps still active. The dive was 36 minutes and in that time we traveled about 100 meters. The watertemperature was 3 °C!.
Although i made about 100 cold water dives (below 10 degrees C) i have never before seen active C. mucedo colonies. This observation is also not in line with the literature i know. Read more here.
Yesterday i got two emails notifying me of two separate finds of Pectinatella magnifica in The Netherlands. One is in a pond in the Sweelinckpark Tilburg and the other in the Piepertkolk in Zwartsluis.
The Tilburg find was by Mr. D. Hamers and Mr. R v/d Oetelaar. Several colonies were observed and many more suspected in the murky waters.
The photo below is with thanks to Mr. H. Hamers.
With special lighting techniques it can be shown that a thin skirt surround the statoblat extending beyond the spines.
As far as i know this is the first time the skirt is described. Nor [Mundy], nor [Wood_II], nor any other source i am aware of has described this.
A key question is what the purpose of the skirt is. Possibly it improves the statoblast's floating ability by using the surface tension of the water surface. Possibly it extends the ability to float, if the gas in the annulus that floats the statoblast escapes after a short time.
Another key question is what the spines are for. Generally it is assumed they anchor the statoblast to other objects, such as aquatic plants or aquatic bird feathers (e.g ducks). It could well be that their real role is to support and spread the skirt to bring it in optimal contact with the surface.
For more details please see here.
Studying microsocopic videos of P. articulata shows that food paricles that come near the mouth are actively succed in before swallowing. This short video (1,5 MB) shows that.
For more P. articulata videos please see the picture page.
On the walls of the tunnel that allows a stream under an road i found P. fungosa colonies, both in classical bulbous and 'lawn' form and in CREEPING FORM! Clearly separated red-brown tubes with here and there a polyp. According to all literature i am familiar with P. fungosa does not exist in a creeping form. Still, on many other places on the same wall were colonies that were clearly P. fungosa. I did not find any other bryozoans. The polyps of the creeping form were of the same size as the P. fungosa polyps and too small for P. repens. Other species do not even look like this.
For pictures see the P. fungosa page!
After earlier P. magnifica statoblast finds by Waterschap Hunze en Aa in the Oostermoervaart in Zuidlaren, now multiple and large colonies are observed and photographed.
This is a first for the Netherlands!
See more pictures behind the small P. magnifica picture on the main page.