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Types of Sirenians

Sirenians Include Manatees, Dugongs and One Extinct Species


The Order Sirenia includes manatees and dugongs, also known as "sea cows," probably because they graze on sea grasses and other aquatic plants. Sirenians are found along the coasts and inland waterways of the United States, Central and South America, West Africa, Asia and Australia (Distribution Map).

1. Manatees

West Indian Manatee
James R.D. Scott/Moment Open/Getty Images
There are 3 species of manatees, and they are found along the coasts of the southern United States, Central America, South America, and West Africa. Manatees are large animals, growing to about 10-15 feet and weighing an average of 1,000 pounds. They have a whiskered face, stout, round body and round, flattened tail. Manatees and are herbivorous, feeding on aquatic plants.

2. Dugongs

Dugong / Stephen Frink, Getty Images
Stephen Frink / Getty Images

There is one dugong species living today, which is simply called the dugong. Dugongs live in warm waters along the coasts from East Africa to Australia. This range spans at least 48 countries. They can grow to lengths of 8-10 feet and weights of up to 1,100 pounds. Dugongs are gray or brown in coloration and have a whale-like tail. Like Manatees, dugongs are sirenians and feed on aquatic plants.

Dugongs are listed as vulnerable on the IUCN Red List. Threats include coastal development and hunting by indigenous peoples.

3. Steller's Sea Cow (Extinct)

The Stellar's sea cow was discovered in the 1700's and hunted to extinction soon after. This unusual-looking animal was 25 feet long and weighed more than 8,000 pounds. It had a whale-like, forked tail. The Steller's sea cow resembled a dugong, but lived in cold waters in the North Pacific. The sea cow was hunted for its meat, and the population dwindled likely because it was small population with a slow reproduction rate. The last Stellar's sea cow was killed in 1768.
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