P. vulgaris is an aloricate rotifer with four sets of blade-like projections or paddles. These paddles are attached to robust, striated muscles within the body through integumentary hooks. When the muscles contract, they pull the hooks downward, causing the paddles to elevate. Since the rotifer lacks any protective outer covering, it relies on the rapid movement of these paddles for escaping predators.The rotifer’s body features a ciliated corona that surrounds the mouth, leading to the gullet, trophi (jaws), esophagus, stomach, and intestine, with the anus located on the ventral surface. The cilia surrounding the corona serve multiple purposes in feeding and locomotion. In females, which are more commonly found in collections, there is a large ovary consisting of a germarium and vitellarium. The oviduct empties into the cloaca. In contrast, the male reproductive system includes a testis and sperm duct. The rotifer’s tactile sense organs comprise two lateral antennae, a dorsal antenna, and a cephalic retrocerebral organ.