The Family Sirenidae includes aquatic salamanders commonly known as sirens, found primarily in the southeastern United States and parts of Mexico. Sirenids are notable for their elongated, eel-like bodies, small forelimbs, and the complete absence of hind limbs, which distinguishes them from most other salamanders. They retain external gills throughout life, making them fully aquatic, and are primarily nocturnal, feeding on insects, crustaceans, and other small aquatic animals. Sirenids exhibit paedomorphosis, meaning they retain juvenile characteristics into adulthood, and they play important roles in freshwater ecosystems as both predators and prey.