Turbellinidae

Turbellinidae is a family of free-living flatworms belonging to the order Seriata within the class Turbellaria. These are typically small, unsegmented worms that inhabit a variety of aquatic environments, including freshwater, brackish water, and marine habitats. Some species can also be found in moist terrestrial environments. Turbellinids are characterized by their flattened, leaf-like bodies. They possess a ciliated epidermis that aids in locomotion and is often covered in mucus.

The mouth of turbellinids is usually located ventrally and is connected to a muscular pharynx that can be extended to ingest food. Their digestive system is incomplete, consisting of a gastrovascular cavity. They lack specialized circulatory or respiratory systems, relying on diffusion for gas exchange and nutrient transport. Turbellinids are hermaphroditic, possessing both male and female reproductive organs, and reproduction can be sexual or asexual through fission. Many species are predatory, feeding on small invertebrates, while others are scavengers. Their classification within the Seriata order is based on certain anatomical features, including the structure of their reproductive organs and the arrangement of their turbellarian nervous system.