portrait

Description:

A colonial peritrich ciliate, Carchesium. Similar to Zoothamnium but Carchesium is distinguished by zooids with discontinuous myonemes allowing individuals of the branched colony to contract independently. However, the entire colony may contract simultaneously. The stalk of Carchesium contracts in a spiral configuration unlike Zoothamnium and Pseudocarchesium whose stalks are described as contracting in a zig-zag fashion. From freshwater pond near Boise, Idaho. Brightfield.