Sirenians are a group of marine mammals that include species such as manatees and dugongs. They are known for their large, rounded bodies and paddle-like flippers, which help them navigate through water. Sirenians are herbivorous, primarily feeding on aquatic plants, and are often found in warm coastal waters and rivers. These gentle creatures are unique among marine mammals due to their slow-moving nature and reliance on shallow habitats. Sirenians play an important role in their ecosystems by maintaining healthy seagrass beds, which provide habitat for various marine species and help improve water quality.