What does a tough outer tegument do for a flatworm?

A tough outer tegument in flatworms provides several essential functions. It serves as a protective barrier against environmental hazards, including pathogens and physical damage. This adaptation also aids in osmoregulation, helping flatworms maintain their internal water balance in aquatic environments. Additionally, the tegument is involved in nutrient absorption, enhancing the flatworm's ability to obtain resources from its surroundings.