Freshwater crabs are crustaceans that primarily live in rivers, lakes, and streams. They belong to various families, with the most common being the Potamidae and Gecarcinidae. These crabs have adapted to life in freshwater environments, developing specialized gills that allow them to breathe underwater. They typically have a hard exoskeleton and a broad, flat body, which helps them navigate their aquatic habitats. These crabs play an essential role in their ecosystems by helping to break down organic matter and serving as a food source for various predators, including fish and birds. Freshwater crabs are also known for their unique behaviors, such as burrowing into the substrate and displaying territoriality. Their presence can indicate the health of freshwater ecosystems.