The simple answer to whether sea cows and manatees are the same is no, but they are closely related members of the same biological group. The term “sea cow” is the common, non-scientific name used to describe all existing and recently extinct members of the taxonomic Order Sirenia. Manatees are a specific type of sea cow. This aquatic herbivore group is named after the sirens of Greek mythology, likely due to sailors mistaking them for mermaids.
Sea Cows: The Greater Family
The Order Sirenia represents a group of fully aquatic, herbivorous mammals that evolved from land-dwelling ancestors over 50 million years ago, making their closest living relatives elephants and hyraxes. These large, slow-moving animals are found in warm, shallow coastal waters, estuaries, and rivers across the globe. They are characterized by streamlined bodies, paddle-like forelimbs, and the absence of hind limbs, which are reduced to internal vestigial bones. The Sirenia order includes two surviving families: Trichechidae, which contains all manatees, and Dugongidae, which holds the dugong.
The order also historically included the massive Steller’s Sea Cow (Hydrodamalis gigas), which was once the largest sirenian, growing up to 10 meters long and weighing over 10 tons. This species was unique among the group for inhabiting the cold, sub-Arctic waters of the Bering Sea. The Steller’s Sea Cow was hunted to extinction within just 27 years of its discovery by Europeans in 1741.
Manatees and Their Geographic Identity
Manatees belong to the genus Trichechus and are easily recognized by their large, rounded bodies and horizontal, paddle-shaped tails. Their skin is thick, wrinkled, and often gray. They possess flippers, which may have three or four small nails. Manatees are specialized herbivores, consuming over 60 different species of aquatic plants and constantly replacing their worn-down teeth in a process called “marching molars.”
There are three living species of manatee, each occupying a distinct geographic range and habitat type. The West Indian manatee (T. manatus) is found throughout the Caribbean, Gulf of Mexico, and as far north as Florida, utilizing both freshwater and saltwater environments. The West African manatee (T. senegalensis) inhabits rivers, estuaries, and coastal areas along the west coast of Africa, from Senegal to Angola. Uniquely, the Amazonian manatee (T. inunguis) is the only species that lives exclusively in the freshwater systems of the Amazon River basin.
The Crucial Distinction: Manatees Versus Dugongs
The primary difference between manatees and dugongs, the other surviving type of sea cow, lies in their physical structure and preferred habitat. The most obvious visual distinction is the tail shape: manatees have a broad, rounded, single-lobed tail that resembles a beaver’s paddle. Dugongs, conversely, have a tail that is distinctly fluked, similar to those found on whales or dolphins.
The structure of their snouts also reflects their feeding ecology. Manatees have a shorter, more rounded snout with a divided upper lip, which allows them to graze on plants both at the bottom and near the water’s surface. The dugong’s snout is longer, trunk-like, and angled downward, making it better adapted for rooting up entire seagrass plants from the seafloor. Dugongs are strictly marine and never venture into freshwater, whereas manatees are often found in fresh, brackish, and saltwater systems.
Geographically, manatees are restricted to the Atlantic Ocean and its connected river systems, including the Caribbean, West Africa, and the Amazon. Dugongs are found exclusively in the Indo-Pacific region, spanning from East Africa to Australia. Another distinguishing feature is that mature male dugongs often possess a pair of small, overgrown incisors that resemble tusks, a characteristic absent in all manatee species.