The Order Sirenia refers to manatees, dugong and Steller's sea cow. While similar in many ways, these Sirenian cousins can be separated into two families, the manatees (family Trichechidae) and the dugongs and Steller's sea cows (family Dugongidae). This fact sheet discusses the characteristics of the family Dugongidae and how they differ from Trichechidae.

The family Dugongidae is made up of only two species, the dugong, extant, and the Steller's sea cow, now extinct. These two species are separated by Genus. Dugongs are members of the Genus Dugong, while the Steller's sea cow was a member of the Genus Hydrodamalis.

The range of these two species of Dugongidae appears not to have overlapped. Dugongs are found along coastlines of the Indo-Pacific, from the coast of East Africa, along coastlines of Asia and Australia, to the East Asian coast as far north as Okinawa. The Steller's sea cow, on the other hand, was a northern Pacific species, adapted to the cold, which used to live along coastlines of the Bering Sea in the North Pacific.

While the range of the two species of Dugongidae did not overlap, neither does the range of Dugongidae overlap with Trichechidae. The range of Dugongidae is Indo-Pacific, while the range of Trichechidae is Atlantic, Caribbean and the Amazon.

Dungongidae differ from Trichechidae in that their tails are fluked, like whales, rather than round, and they have no vestigial nails on their front flippers. The upper lip of Dugongidae is not as deeply split as the upper lip of Trichechidae.

For specific information about dugongs and Steller's sea cows, please refer to their individual species fact sheets.

- Dugongidae information assembled from on-line sources on Sept. 25, 2007 by Kevin Miller for SeaPics.com.

Sources:

http://animaldiversity.ummz.umich.edu/site/accounts/information/Sirenia.html

http://en.wikipedia.org/wiki/Sirenia

http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2003/Harshaw/page2.htm

http://www.thewildones.org/Animals/manatee.html