Manatee vs Dugong: How to Tell Sea Cows Apart

Key differences at a glance

Manatees and dugongs are the only living sirenians, a group often called sea cows. They are slow, gentle plant-eaters with no hind limbs and paddle-like front flippers, and both graze on seagrass. That is where the resemblance ends.

There are three species of manatee: the West Indian manatee of the southeastern United States, the Caribbean and South America, the Amazonian manatee of the Amazon basin, and the West African manatee. There is only one dugong, found in warm coastal waters from East Africa and the Red Sea to Australia and the islands of the southwest Pacific. The table above compares the dugong with the West Indian manatee, the best-known manatee in Europe and North America.

Tail: paddle or fluke?

The tail is the giveaway. A manatee’s tail is a large, flat, rounded paddle, a little like a beaver’s tail but much bigger. A dugong’s tail is split into two pointed flukes with a notch in the middle, very similar to the tail of a dolphin or a whale.

Both animals swim by moving their tails up and down, and both use their front flippers mainly for steering. Manatees also use their flippers to “walk” along the bottom and to hold plants. The West Indian and West African manatees have three or four nails on each flipper, while dugongs and Amazonian manatees have none.

Head, snout and teeth

A dugong’s head points down. Its snout is sharply bent toward the seabed and ends in a broad, horseshoe-shaped muzzle covered in thick bristles, ideal for plowing through seagrass on the bottom. A manatee’s snout is shorter and less downturned, with a split upper lip whose two halves can move separately to grab plants, and it can feed at the surface, on the bottom or on plants at the water’s edge.

Their teeth are very different. Adult manatees have no front teeth but have rows of molars that keep forming at the back of the jaw and moving forward, replacing worn teeth throughout life. Dugongs have only a few simple, peg-like cheek teeth that are not replaced in this way. Male dugongs also grow a pair of short tusks, which are enlarged front teeth that break through the skin at puberty. In females they usually stay hidden in the jaw, though they sometimes appear in old age.

Where do manatees and dugongs live?

Their ranges never overlap. West Indian manatees live along the Atlantic coasts of the Americas, from Florida through the Gulf of Mexico and the Caribbean to Brazil. West African manatees live along the coast and in the rivers of West and Central Africa, and Amazonian manatees live only in the fresh waters of the Amazon basin.

Dugongs live in the coastal waters of about 40 countries and territories across the Indian Ocean and the western Pacific. Northern Australia holds most of the world’s dugongs, and the Arabian Gulf has the second-largest population. They are also found in the Red Sea, along the coast of East Africa and in parts of South and Southeast Asia and the Pacific islands.

The other big difference is water. Manatees move freely between salt, brackish and fresh water, and Florida manatees spend the winter in freshwater springs, as explained in Where do manatees go in winter? The dugong is the only strictly marine sea cow. It may visit brackish mangrove channels, but it depends on seagrass meadows in the sea.

What do they eat?

Both are herbivores, but the manatee has a much broader menu. West Indian manatees eat more than 60 kinds of plants, including seagrasses, freshwater plants such as hydrilla and water hyacinth, algae, mangrove leaves and grasses hanging over the shore.

Dugongs are seagrass specialists. They prefer young, tender seagrasses that are rich in nitrogen and low in fiber, and they often dig up the whole plant, roots included, leaving long, winding “feeding trails” in the sand. By grazing the same meadows again and again, they may even help keep the seagrass in a tender, fast-growing state. More detail is in What do dugongs eat?

Which is bigger?

The manatee is usually the bigger and bulkier animal. Most adult West Indian manatees are 2.7–3.5 m (9–11.5 ft) long and weigh 200–600 kg (440–1,320 lb), and exceptional animals have topped 1,500 kg (3,300 lb). Adult dugongs rarely exceed 3 m (10 ft) and usually weigh about 230–420 kg (510–930 lb). The largest dugong on record, from the coast of western India, measured 4.06 m (13.3 ft) and weighed 1,016 kg (2,240 lb).

Lifespan and breeding

Both sea cows live long lives and breed slowly. Manatees can live 60 years or more in the wild, and females can start breeding at about three to five years old, then usually have one calf every two to five years after a pregnancy of 12–14 months.

Dugongs live even longer, often 70 years or more, a figure scientists measure by counting growth layers in their tusks. They breed more slowly still. Females may have their first calf anywhere between about 6 and 17 years old, then give birth to a single calf every 2.5–7 years after a pregnancy of about 13–15 months. This very slow rate of reproduction means dugong populations can take decades to recover from losses.

Conservation status

On the IUCN Red List, the West Indian manatee, the Amazonian manatee, the West African manatee and the dugong are all listed as Vulnerable. Within these species, some populations are in serious trouble. The Antillean manatee of the Caribbean is Endangered, and in 2022 the dugongs of East Africa were assessed as Critically Endangered and those of New Caledonia as Endangered.

The threats are similar. Both animals drown in fishing nets, are struck by boats, lose their seagrass to pollution and coastal development, and are still hunted illegally in some places. Dugongs have already disappeared from the waters of Taiwan, Hong Kong and Mauritius.

Are manatees and dugongs related?

Yes, but not closely. Both belong to the order Sirenia, whose closest living relatives are elephants and hyraxes. The manatee and dugong families split from each other more than 30 million years ago, and because they live on opposite sides of the world, they cannot interbreed and no hybrid has ever been recorded.

The dugong’s closest relative was Steller’s sea cow, a giant cold-water sirenian of the North Pacific that grew to about 8–9 m (26–30 ft). It was described by European scientists in 1741 and hunted to extinction by about 1768. Some of the history behind the sea cow names, and the mermaid legends linked to both animals, is told in Why are manatees called sea cows? and Were manatees mistaken for mermaids?