Merismopedia

I did manage a few water samples before freeze-up and one of them held a specimen I hadn't seen before.  It was from the genus Merismopedia, a member of the cyanobacteria. They reproduce by fission in two planes, thus forming sheets with a thickness of one cell.

This specimen was collected from shoreline sediment on the La Salle River.

The cells are about 2 microns in size. The photo was taken in phase contrast with a 40x objective.