Spirostomum, photographed 1/14/26 at 250x (left) and 1/17/26 at 1000x (right). Among the most charismatic of the protozoans (or at least, as charismatic as a protozoan can be... they're all charismatic to me!) due to how large they get. You can see these folks without a microscope! That is, until they contract to a fraction of their size. It's done in a spiral motion, hence the name. The ones in these photos are pretty large, but ones I've found more recently have been quite small. Lots of variation! They can reproduce sexually by conjugation, but tend to do so with similarly sized individuals. I wonder how they tell?














