pellicel

A pellicle is a thin, flexible, yet rigid outer layer that surrounds certain protozoa and other microorganisms. It provides structural support and protection, maintaining the cell's shape and preventing it from bursting in hypotonic environments. Unlike a cell wall, the pellicle is typically composed of proteinaceous material and is flexible enough to allow for some degree of movement, such as amoeboid locomotion or changes in shape during feeding.

The structure and composition of the pellicle can vary significantly among different species. In ciliates, for example, the pellicle is a complex layer often associated with cilia or other external organelles. In flagellates like Euglena, the pellicle allows for characteristic wriggling or metabolic movements. The pellicle plays a crucial role in the organism's survival, enabling it to interact with its environment, resist mechanical stress, and regulate the passage of substances into and out of the cell. Its presence is a defining feature of many protozoan groups and contributes to their ecological success in diverse habitats.