Are Dugongs and Manatees Related?

Gray in color. Short oval shape. Two flippers and a tail. These are the features found in both manatees and dugongs. But the similarities do not end there.

Manatees and dugongs are large-bodied, slow-moving and docile herbivores found in shallow water areas in warm coastlines and some freshwater bodies. They spend most of their day floating elegantly in water, taking several hours grazing on sea grasses and swimming gracefully with their powerful tails and flippers. Because of their slow nature and grass-eating tendencies, both manatees and dugongs are called sea cows, and their large size and gentle but curious nature makes them attractive creatures.

Belonging to the same order: Sirenia

Manatees and dugongs are mammals of the order Sirenia—that is, sea cows. The word Sirenia comes from Greek mythology to describe mermaids. The first sailors were persuaded to believe that these creatures were sirens (mermaids), hence the name of the order. Sirenians are unique marine animals because they are strictly herbivorous.

Manatees and dugongs are the two presently existing families of the order Sirenia. Among manatees, there are three living species, while just one species of dugongs is currently in existence—though researchers have shown that dugongs are the ones with the most subspecies (19).

The four living species of the order Sirenia are the Amazonian Manatee, the dugong, the West Indian Manatee and the West African Manatee. By the year 1768, there was a third family of the order Sirenia, the Steller’s Sea Cow, but it went extinct just 27 years after its discovery following massive hunting. The Steller’s Sea Cow was closer to dugongs than to manatees.

How big are they?

Dugongs and manatees have a relatively long snout, horizontal tail (like whales and dolphins) and short round paddle-like flippers. They can grow to 4 meters in length and weigh up to 450 kilograms. However, manatees are generally larger than dugongs, weighing 400-500 kilogram and growing to a length of 3.6 meters. Dugongs rarely grow longer than 3 meters and weigh on average 420 kilogram.

While manatees have horizontal tails with just a single lobe to move up and down as the animal swims, a dugong has a fluked tail with two separate lobes joined together in the middle. Manatees have divided upper lip and shorter snout for gathering food and feeding on plants, while dugongs have broad, short, trunk-like and downward facing snout with a slit for the mouth that’s useful when feeding off ocean floor.

Dugongs have overgrown incisors set at the front of the mouth and resembling small tusks. The incisors are usually only obvious in adult males. Manatees lack incisors and instead have marching molars (hind molar progression). Actually, manatees continually grow molars in the back quarters of their mouths such that when the front teeth grind down and ultimately fall out, the molars fully emerge and push new teeth forward.

Social life

Manatees and dugongs are solitary animals though they have different approaches when it comes to mating partners. For instance, manatees are devout polygamists with males having several partners. Female manatees give birth at the age of 3-5 and have successive births every 2-3 years. On the other hand, a female dugong lives with only one male for years. Females begin to give birth at the age of 10 and continue to do so every 3-5 years.
Dugongs spend their entire life in shallow, sheltered coastal areas such as bays and mangrove swamps. They never leave saltwater. But manatees can live in both freshwater and saltwater. In fact, although the West African and West Indian Manatee reside primarily in saltwater and migrate to warmer freshwater areas in winter, the Amazonian Manatee resides only in freshwater. Nevertheless, neither manatees nor dugongs can survive in cold water. They have to make the journey to warm water areas every winter.

Threats faced

Dugongs and manatees are highly vulnerable mammals. Both are exploited for bones, meat, oil and skin. Both face dangers such as accidental entrapment in fishing lines and nets, being hit by boats and ingesting plastic. They are also threatened by loss of habitat when mangroves are cleared, wetlands destroyed and rivers dammed.

Manatees and dugongs are close cousins. They have a lot in common, are incredibly wonderful creatures and great to spend time with in the water.

At Captain Mike’s, we love these mammals and sharing information about them. We offer manatee tours in Crystal River, Florida for those who would like a memorable and delightful day in the water. For more information about manatees, manatee tours, kayaking and scalloping trips in Crystal River, Florida, visit Captain Mike’s Swimming with the Manatees website.

Are manatees and dugongs the same thing?

Manatees and dugongs are sea mammals of the order Sirenia. The animals are both large, slow-moving herbivorous mammals commonly found in shallow water areas along warm coastlines. Generally, there are 4 living species of mammals in the order Sirenia. They include the Amazonian manatee, the West Indian manatee, the dugong and the West African manatee, though the extinct Stellar’s sea cow (massively hunted to extinction in the eighteenth century) also falls in this order.So what is the difference between the dugongs and manatees?

1. Habitat

Manatees are typically found in the marshy areas of the Amazonian basin (Amazonian manatee), Gulf of Mexico and the Caribbean (West Indian manatee) and West Africa (the West African manatee). Since they cannot stand temperatures below 15 degrees Celsius, the manatees migrate often to avoid cold waters. On the other hand, dugongs spend their whole life in shallow, protected areas like mangrove swamps and bays. They are found around the coastlines of Africa and the Pacific, in places like Volanculos/Bazaruto in Mozambique, Marsa Alam in Egypt and the waters off northern Australia. Dugongs are the only Sirenians found only in saltwater and their only diet is sea grass.

2. Tails and Nails

Manatees and dugongs have an almost completely similar fusiform body structure, which is only different at the tail. Manatees have a very large, horizontal and paddle-shaped tail with just one lobe. The tail wags up and down when a manatee swims. The tail of a dugong has flukes with pointed projections, similar to a whale with a somewhat concave trailing edge. While the dugongs and Amazonian manatees do not have nails, the West African and West Indian manatees have basic nails on the forelimbs.

3. Mouth and Nostrils

The angle of a manatee’s mouth is less pronounced than that of a dugong. The dugong has short, broad and downward facing trunk-like snouts that are horseshoe-shaped with slit-like mouths and undivided upper lips. Due to their mouth structure, dugongs are bottom-dwelling. In contrast, manatees have divided upper lips and shorter snouts, which enable them to gather food and to feed on plants that grow on or near the water surface. In terms of nostrils, the nostrils of dugongs are located farther back on the head than those of manatees.

4. Teeth

Mature male dugongs usually have a pair of incisors shaped like tusks. Manatees do not have incisors. Instead, the manatees have molars which get replaced continuously. When the molars of a manatee move forward, often stimulated by the chewing motion, they gradually shift toward the front jaw and eventually fall out once in the front. As the molars shift to the front jaw, new molars appear at the back jaw to replace them. Typically, a manatee will not have more than 6 teeth in each jaw at any given time. But in dugongs, the molars in the back jaw are open-rooted and will continue to grow as they wear away.

Social Life and Offspring

Generally, manatees are solitary creatures that prefer to graze alone for long hours every day. A male manatee can have several female partners since the males usually compete to mate the females. Female manatees can give birth when 3 years old and then continue to do so after every 2-3 years, with the gestation period lasting 12 months each. On the other hand, dugongs are more solitary than the manatees, preferring to live in pairs and with only one mate. Female dugongs tend to give birth at the age of 10 years and then at intervals of 3-5 years after that.

Manatees and dugongs are very close cousins, which is why they have many similarities and few differences. They are incredibly wonderful creatures and a great sight to behold for nature lovers. So if you are planning to go on vacation and want to see one of the endangered species, then going to a place where you can see a manatee or a dugong can provide you with one of the most fulfilling trips.

At Captain Mike’s Swimming with the Manatees, we have been offering manatee tours to nature lovers for a long time. If you are planning a trip to see or swim with manatees at Crystal River, Florida, then working with us can bring all the glamour and joy you need in your trip. For more information, visit the “Captain Mike’s Swimming with the Manatees” site.

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