Dugongs and manatees are often confused due to their similar appearance. Both are large, slow-moving aquatic mammals belonging to the order Sirenia, commonly known as “sea cows.” This group includes four living species, all of which are entirely aquatic and primarily herbivorous.
Not the Same Animal
Dugongs and manatees are distinct marine mammals, despite their shared “sea cow” moniker and order, Sirenia. This order encompasses four living species: the dugong and three manatee species (West Indian, Amazonian, and West African). They are classified into different families and genera; the dugong is the sole living representative of the family Dugongidae, while manatees belong to Trichechidae. This taxonomic separation highlights their unique evolutionary paths.
Shared Lineage and Similarities
Dugongs and manatees share a common ancestry within the order Sirenia, accounting for their general resemblances. Both are large, grey, fusiform (spindle-shaped) creatures with thick skin, sometimes appearing brown or green from algae. They are entirely aquatic, spending their lives submerged and surfacing to breathe, and are herbivores, grazing on seagrass and other aquatic vegetation. Their gentle, slow-moving nature contributes to the common confusion between them.
Distinctive Features and Habitats
While both are stout, grey-bodied marine mammals, dugongs and manatees have several distinguishing physical characteristics and inhabit different environments. Their tails are a noticeable difference: dugongs have a fluked, dolphin-like tail with two lobes, while manatees have a rounded, paddle-shaped tail. Their snouts also differ; dugongs have a broad, downward-pointing, shovel-like snout for bottom feeding, whereas manatees have a shorter snout with a split upper lip, allowing them to grasp vegetation near the water’s surface.
Differences extend to their dentition. Adult male dugongs and some older females develop tusklike incisors, absent in manatees. Manatees, conversely, have a unique “marching molars” dental system, where new molars continuously grow at the back of the mouth and move forward to replace worn teeth. Both species use their flippers for steering and bringing food to their mouths.
Their habitats and geographic distributions also vary. Dugongs are exclusively marine mammals, found in warm, shallow coastal Indo-Pacific waters from East Africa to Australia, relying heavily on seagrass meadows. In contrast, manatees inhabit a wider range of environments, including coastal marine waters, estuaries, and freshwater rivers across the Atlantic basin and African coast. Manatees tolerate brackish and freshwater conditions, with some species migrating to warmer freshwater areas during colder months. While both are primarily herbivores, dugongs feed almost exclusively on seagrass by rooting entire plants, whereas manatees consume a broader variety of aquatic plants.
Conservation Status
Both dugongs and manatees face threats and are vulnerable to extinction. They are susceptible to habitat loss, particularly the degradation of seagrass beds, their primary food source. Coastal development, water pollution, and climate change, leading to extreme weather and altered water conditions, further threaten these habitats.
Human activities like boat strikes and entanglement in fishing gear are leading causes of injury and mortality. Their slow-moving nature makes them vulnerable to collisions with watercraft. Conservation efforts focus on protecting habitats, reducing human-related mortalities, and implementing measures like “go-slow” zones in key areas. Despite protective laws and international agreements, populations continue to decline in many regions.