Paramecium caudatum typically measures between 170 and 330 micrometers in length, commonly falling within the range of 200 to 300 micrometers. Its cell body is spindle-shaped, with a rounded front end and a tapering posterior that culminates in a blunt point. Early observers often likened its shape to that of a slipper, hence its nickname, the “slipper animalcule.” The pellicle, which covers the entire surface of the cell, is adorned with cilia and features a lengthy oral groove leading to a deeply embedded oral cavity lined with cilia, which function as both locomotory organs and aids in food capture. P. caudatum possesses two contractile vacuoles responsible for expelling excess water absorbed from the environment, thus regulating the body’s water content. These contractile vacuoles exhibit a star-like appearance due to radially distributed “collecting canals.” The cell is enveloped by a cellular cortex densely populated with spindle-shaped structures called trichocysts.