The Family Proteidae includes aquatic salamanders commonly known as mudpuppies and waterdogs, found in North America and parts of Europe. These amphibians are fully neotenic, retaining larval features such as external gills throughout their lives, and are entirely aquatic. Proteids have elongated bodies, well-developed tails, and four limbs adapted for swimming. They are mostly nocturnal and carnivorous, feeding on insects, worms, and small aquatic animals. As fully aquatic salamanders with limited dispersal, members of Proteidae are important indicators of freshwater ecosystem health.