Learn about the unicellular ciliated protozoan Paramecium, its classification, features, locomotion, nutrition and reproduction. See diagrams, examples and FAQs on Paramecium and its life cycle. Description A diagram of Paramecium caudatum Species of Paramecium range in size from 0.06 mm to 0.3 mm in length. Cells are typically ovoid, elongate, or foot- or cigar-shaped. The body of the cell is enclosed by a stiff but elastic structure called the pellicle. Learn about Paramecium, a single-celled protist with cilia, and its diagram, structure, nutrition and reproduction. See how Paramecium feeds, moves, osmoregulates and undergoes asexual and sexual reproduction. Paramecium is a eukaryotic genus commonly used as a ciliate model organism. This article will focus on details of Paramecium, diagram , classification, characteristics, size, locomotion, reproduction and more