Choanocytes are specialized cells found in sponges, which are simple aquatic animals. These cells have a unique structure featuring a collar of microvilli surrounding a single flagellum. The flagellum beats to create a water current, allowing the sponge to filter food particles from the water. The primary function of choanocytes is to facilitate feeding and respiration. As water flows through the sponge's body, choanocytes trap and engulf tiny organisms, such as bacteria and plankton. This process not only provides nourishment for the sponge but also helps maintain water circulation within its porous body.