Dugongs and manatees are large, similarly sized, and shaped marine mammals. They can be mistaken for one another. But, if you know the difference, it’s fairly easy to tell them apart. Below, readers can explore a few of the ways that dugongs and manatees are similar and the important ways they are different.
Credit: Julien Willem (left) and Albert kok (right)
Main Differences Between a Dugong and a Manatee
- Appearance: Dugongs and manatees are very similar in appearance, with no dorsal fins and snouts to feed on the ocean floor. Saying this, manatees have unique cervical vertebrae of only seven, whereas all other mammals have seven. Manatees also have a divided upper lip and a shorter snout than dugongs.
- Size: Dugongs are much smaller, growing to 9 feet long and up to one metric ton, whilst manatees grow up to 13 feet long and up to 500kg.
- Habitat: Dugongs are found in the Indian Ocean and the West Pacific Ocean, as well as Australian waters and mangroves. Manatees enjoy coastal and similar waters to dugongs and habitat areas such as Florida, West Africa, the Amazon Basin, and the Gulf of Mexico. Both species prefer to live in warmer water.
- Diet: Dugongs predominantly eat seagrass, whilst manatees eat similar plants such as turtle grass, sea clover, marine algae, and shoal grass.
- Speed: Both dugongs and manatees are very slow moving, which often results in them getting injured by things such as boat propellors.
We’ll explore these differences and interesting facts about marine animals below.
The dugong is a species of sea cow. It is the only remaining member of the Dugongidae family. It’s a large animal lacking a dorsal fin or hind limbs. Its closest living relative is the manatee. Like all sea cows, it has a very small brain size compared to its body size.
Dugongs are large animals that can grow to be around nine feet in length. They can even weigh up to one metric ton. As noted above, the dugong has no dorsal fin or limbs. They have a fluked tail, which has two separate lobes that join together in the middle. Dugongs use their forelimbs, or flippers, combined with their dolphin-like tail, to paddle through the water. They are usually seen with their downturned trunk-like snouts along the ocean floor, seeking out seagrass to eat. The dugong males grow tusks during the mating season if their testosterone level is high enough, thus signifying their success as a potential mating partner.
Dugongs are found throughout the warm waters of the Red Sea, the Indian Ocean, and the West Pacific Ocean. There are small populations of dugongs found in East Africa. Their entire lives are spent in coastal waters where grassy meadows and mangrove swamps are common. They were populations that lived in bays, mangrove channels, and waters around islands. Today, the largest population, which is itself declining, is found in Australian waters. It is between Shark Bay and Moreton Bay.
Dugongs are herbivores. They eat seagrass and do not have advanced hunting capabilities. When there is no grass available to pull up with their lips and teeth, they’ve also been known to eat algae. They’re also some instances in which they have been seen eating jellyfish and shellfish.
Dugongs use internal fertilization to reproduce. Their younger ones are born large and can spend up to a year and a half with their mothers nursing. They have a long life span and an extended period of time between reproductive periods. These are two of the reasons why the population is in decline. As the animals are hunted or die due to changes in their habitat, it is difficult to replace the population.
Despite being very similar in body composition, the main physical differences between the female and male dugongs are their genitalia. Female dugongs have different genital placement, while dugong males have internally positioned genitalia. Dugong uses ‘lekking’ as a way of mating, which involves male-on-male combat. After a mate has been selected, the gestation period is 13 to 15 months. Due to this, female dugongs can only reproduce a few times across their entire lifespan.
Manatees are large herbivores that are sometimes known as sea cows. There are three species of manatee making up three of the four living species of the order Sirenia, the fourth being the dugong. The three species of manatee are:
- Amazonian manatee or (Trichechus inunguis)
- West Indian manatee or (Trichechus manatus)
- West African manatee or (Trichechus senegalensis)
Interestingly, manatees have also played an important cultural role. They have been linked throughout history to mermaid folklore. Sailors often mistook manatees for sirens, making the inspiration behind many mermaid tales. In some cultures, such as in West Africa, they have been considered sacred and even thought to be once human. This is not dissimilar to dugongs’ role in countries like Australia.
Like the dugong, these are large animals. They grow to similar lengths, around thirteen feet long but weigh up to 1,300 pounds. Manatees also have paddle-like flippers, similar to those that dugongs use. The manatee’s tail is the clearest difference in appearance. They have paddle-shaped tails, while the dugong’s tail is fluked like a whale’s. Another difference in appearance is the manatee’s snout. It is shorter than the dugongs.
Interestingly, the manatee has unique cervical vertebrae. It has only six, whereas all other mammals have seven. That is, except for two types of sloths.
The teeth of a manatee are also a unique feature. With no incisors or canine teeth, they solely have cheek teeth, which are not clearly identifiable as either molars or premolars.
They also prefer to live in shallow, coastal areas, for example, around the Amazon Basin, the Gulf of Mexico, and West Africa. Manatees are also a migratory species. In the United States, they live around the coast of Florida in winter and are also seen in the marshy areas of the Caribbean. The three species of manatee are primarily distinguished by where they live, for example, in the Amazon Basin or along the coast of West Africa. Manatees tend to live alone unless a male manatee is looking to mate or a young manatee is with its mother.
When manatees are born, they weigh around 66 pounds or 30 kg each. They breed once every two years, and a single calf is born, like the dugong. Manatees become sexually mature around five years of age. If a manatee loses a calf, it may experience an interval of two years before another is born. It can take up to a combined 30 months, 12 months of gestation, and 12 to 18 months of weaning before female manatees can engage in another estrous cycle.
Like dugongs, manatees are herbivores. They eat around 60 different freshwater and saltwater plants. They have also been known to eat fish from nuts. Some examples of plants that they enjoy include turtle grass, sea clover, marine algae, and shoal grass.
Threats to Manatees and Dugongs
In the 18th century, the Stellar’s sea cow, another member of the sea cow family, was hunted to extinction. Today, both species are threatened by human encroachment on important habitats, pollution, and climate change. Both dugong and manatee young are threatened by predators like crocodiles.
Both manatees and dugongs are slow-moving creatures. This means that they are threatened by coastal development and vessel strikes. This is one of the leading causes of death or injury to these large creatures. Many manatees exhibit scars from encounters with vessels, such as propeller-driven boats and ships. If the initial collision does not take the manatee’s life, the resulting infection may.
Another human-caused threat to the manatee’s life is also boat-related. Many ships emit low frequencies that confuse manatees. This has been posited as a reason why so many of these large creatures have collided with vessels. Fishing nets and other objects below and on the surface of the water can impact the safety of these wonderful animals.
For these reasons, manatees, especially, have become extremely endangered, and under the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973, Florida manatees are now closely protected.
Do manatees reproduce asexually or sexually?
Manatees reproduce sexually, like dugongs. They use internal fertilization with one calf iron every two to five years.
Are manatees and dugongs the same?
No, these are two different species. They are somewhat shapes and sizes, but the dugong has a more down-turned snout. Dugongs are usually smaller than manatees and have fluked tails, like whales.
Are manatees endangered?
Manatees are considered threatened. They are at risk from a variety of human-caused sources. One of the primary threats they face is vessel strikes. They can get cut by or caught up in ship propellers.
Where are most dugongs located?
In recent years, the highest population of dugongs has been found in northern Australian and western Australian waters. Other populations are found in the waters of the Indian Ocean, with small populations being discovered in East Africa.
Can you see manatees in Australia?
Technically you can not see manatees in Australia; however, their very close relative, the dugong, is native to Australian waters. Many conservation efforts are going on in Australia in order to preserve the dwindling population of dugongs and keep them in Australia for years to come.