AN UNUSUAL (?) PROTOZOA

by Bill Ells, UK

A sample sent to me by Anne Bruce editor of the Micscape Newsletter, collected by Alastair Bruce from Slugain Glen in Scotland is extremely interesting. It contains a desmid Cosmarium nymannianum which I cannot recall seeing before although its distribution is widespread throughout Britain according to W.& G.S.West in their Monograph of the British Desmidiaceae. I also found, one specimen only, of a rotifer Lepadella pterygoides identified for me by Eric Hollowday. I have been searching the sample for another specimen or a lorica in order to get a photograph or at least a detailed drawing of what I now know to be a vary rare animal.

There are many specimens of a protozoa I have never seen before which I expect readers of this article will be able to identify. I have not found it in any of the limited literature I have on the protozoa. Fully extended (a) it is 215 mm long, It retracts as swiftly as Vorticella to which the head has some resemblance, unlike Vorticella it retracts not by coiling a stalk-like attachment but by reducing its body to about a ¼ of its extended length. (b) is the shape after reduction, many specimens had a short tail which did not reduce in size (c). It soon started to slowly extend again, when nearly full length was reached (c), cilia could be seen moving within the apex, as the head started to unfold the cilia would appear sticking straight out, and would then fold down until nearly at right angles with the body, waving throughout (a). The cell walls are smooth and colourless, material can be seen within the body, however comparing different specimens no definite pattern could be made out.

Keeping observation and trying to get a decent drawing, particularly of the head, was very frustrating. It took from 5-10 minutes for the head to fully unfold when it usually immediately swiftly retracted again. Sometimes it would retract even before the head unfolded, possibly because of some disturbance on my part. Any effort to change objectives would result in swift retraction.

Comments to the author Bill Ells are welcomed.

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Published in January 1999 Micscape Magazine.

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