[Annelida] Tiny fresh water worms

Ariel Chipman via annelida%40net.bio.net (by chipman from cc.huji.ac.il)
Thu Nov 26 08:13:45 EST 2009

Dear annelid enthusiasts,

As a non-annelid specialist, I wonder if someone in this list can help  
with identifying some very small worms that have invaded a paramecium  
culture that I have been maintaining for teaching. The culture is  
fresh water, but is far from clean, and includes input from various  
different sources, so it is next to impossible to trace where they  
came from. They are roughly a millimeter long, have definite segments  
with chaetae, no obvious eyes, and no external mouthparts. They are  
generally soft bodied and very flexible. A hard pharynx is visible  
(but not obvious in the photos), and they seem to be feeding on plant  
matter, rather than the Paramecia that surround them (I infer this  
from green matter in their guts, and because I think I saw them  
browsing on plant material, but never attacking a Paramecium). I  
showed them to our local annelid expert, Nechama Ben-Eliahu. She  
suspects they are archiannelids, but they don't fit in with any of the  
keys she has. I attach two photos, which I have scaled down for  
sending, but can provide higher resolution versions (and more photos)  
if anyone is interested. One photo is lower magnification and shows  
two individuals of slightly different sizes. The second photo is a  
hihger magbnification of the head region, with a Paramecium for scale.

I would be happy for any help in identifying these critters.


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Dr. Ariel Chipman
Senior Lecturer
Academic Curator of Aquatic Invertebrates
Dept. of Evolution, Systematics and Ecology	
The Hebrew University of Jerusalem
Givat Ram Campus
Jerusalem 91904

Office phone: ++972-2-6585816
Lab telefax:    ++972-2-6585809
ariel.chipman from huji.ac.il

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