Manatees and dugongs are large, gentle marine mammals. While they share many characteristics, these two species are distinct. This article explores their unique features and shared traits.
Not the Same But Related
Manatees and dugongs are closely related, both belonging to the order Sirenia. This order includes all “sea cows” and is unique as its members are the only fully aquatic herbivorous mammals. Within Sirenia, manatees are classified under the family Trichechidae, while dugongs are the sole living representatives of the family Dugongidae. This classification recognizes their shared ancestry and evolutionary divergence.
Key Differences
Manatees and dugongs exhibit several distinct physical characteristics. A primary distinction is their tail shape: manatees possess a rounded, paddle-like fluke, similar to a beaver’s. In contrast, dugongs have a notched, dolphin-like tail, aiding their propulsion.
Their snouts also differ, reflecting their feeding strategies. Manatees have a broader, squarer snout with a divided upper lip, allowing them to graze on aquatic plants at or near the water’s surface. Dugongs feature a shorter, downturned snout, adapted for bottom-feeding where they efficiently uproot seagrasses from the seafloor. Male dugongs can develop small tusks, which are modified incisors, a feature absent in manatees.
Manatee teeth are continuously replaced from the back of the jaw, moving forward like a conveyor belt, whereas dugongs have a finite number of peg-like molars. Manatees are bulkier, reaching up to 13 feet long and weighing around 1,200 pounds, while dugongs are more streamlined, growing 7 to 11 feet and weighing up to 925 pounds.
Shared Traits and Lifestyle
Manatees and dugongs share numerous biological and behavioral traits. Both are herbivores, primarily feeding on aquatic vegetation such as seagrasses and other water plants. They are slow-moving creatures, typically cruising at speeds of about 3 to 5 miles per hour.
Their general body plan is similar, characterized by large, fusiform (torpedo-shaped) bodies, front flippers, and the absence of hind limbs or a dorsal fin. Both species are air-breathing mammals and must regularly surface to inhale. Their nostrils are located on top of their heads and can be sealed underwater. They also possess dense bones that help them manage buoyancy in the water.
Where They Live
The geographic distribution of manatees and dugongs provides another clear distinction. Manatees are primarily found in the shallow coastal waters of the Atlantic Ocean. This includes regions like the Caribbean Sea, the Gulf of Mexico, the Amazon Basin, and along the West African coast. Manatees are adaptable, inhabiting both saltwater and freshwater environments.
Dugongs, conversely, have a distinct range. They are exclusively found in the coastal and shallow waters of the Indo-Pacific region. Their habitat stretches from East Africa across to Australia and the Pacific Islands. Unlike manatees, dugongs are strictly marine mammals and do not venture into freshwater. Their ranges do not overlap.