Dugong, Dugong dugon, Stock Photos, Pictures, Images

The dugong, Dugong dugon, is the most widely distributed species of sea cow, with populations in the western Pacific Ocean, the Indian Ocean, East Africa, the Persian Gulf, Japan, Australia, and the Philippines. The largest population, around 85,000, can be found in Australia.

In the family Dugongidae, the dugong is in the same order Sirenia as the manatee (family: Trichechidae). The dugong is smaller than the manatee about 2.7 meters in length (9 ft) when fully grown and has a fluked, whale-like tail, as opposed to the rounded tail of the manatee. It weighs on average 275 kg (600 lbs), but some individuals have been known to reach 3.3 meters (11 ft) and a weight of 400 kg (880 lbs). The dugong spends its entire life in the sea.

Young dugongs are a cream color, which turns to gray as they age. They have tough, thick skin, which is smooth, unlike the wrinkled skin of manatees. They propel themselves with their tail, and use their 35-35 cm long fins for steering and for stabilizing themselves on the muddy sea floor. Dugongs make a whistling sound when frightened, and calves are known to bleat underwater.

Dugongs flourish in warm tropical waters where seagrass is abundant. They forage on the sea bottom, at depths of 1 to 5 meters, and uproot whole plants with their long, flexible snouts, leaving a trail in the mud. Dugongs must surface every minute or two to breathe through the valved nostrils at the top of their snouts. Unlike dolphins and whales, dugongs cannot hold their breath for long, particularly when active.

Dugongs begin reproducing at about 9-10 years of age. Their gestation period runs about a year, and they nurse their young from the two teats located at the base of their flippers for 14-18 months. They typically give birth to just one calf. Under optimum conditions, a dugong may live up to 70 years.

Threats to the dugong include hunting and collisions with boats, but the main danger is degradation of habitat, which is often caused by eutrophication, generally resulting from agricultural runoff. They also have natural predators, such as sharks and crocodiles.

A relative of the dugong, though much larger, was the Steller's sea cow, which became extinct in the late 1700's due to over hunting.

The dugong is said to be the origin of the mermaid myth. The name of their order, Sirenia, comes from the ancient Greek myth of the Sirens (or Seirenes), who were part bird, part woman, and who lured sailors to their doom with their bewitching songs.

Dugong, Dugong dugon, Indonesia, Indo-Pacific Ocean. Image #: 005042	Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Sirenia Family: Dugongidae Genus Species: Dugong dugon
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More about the differences between manatees and dugongs:

Dugongs are smaller, lighter and more streamlined than manatees, and are more strictly marine mammals. The tails of the two species are different, with the manatee's being rounded and the dugong's whale-like. Dugongs have smoother skin than manatees and are less likely to be covered with algae. Manatees have sparsely distributed hairs on their bodies, which dugongs lack. Dugongs do not replace their teeth like manatees, and dugongs have tusks, which manatees do not. Dugongs can be found in deeper waters than manatees, but manatees are able to stay submerged longer. Dugongs do not have the elephant-like nails on their fins that manatees have. Dugongs have 7 cervical vertebrae, while manatees have 6. There are differences in the kidneys of the two species, probably as a result of differences in their diets and in the respective salinity of their habitats. The ranges of manatees and dugongs do not overlap, with dugongs being found in the shallows of the Pacific, Asia, East Africa and Australia, and manatees being found in the shallows of the Atlantic, Caribbean and the Amazon basin.

For an illustration comparing species and species size in the order Sirenia, see: http://www.sirenian.org/caryn.html

- Dugong information assembled from published and on-line sources by Kevin Miller for SeaPics.com. Oct. 20, 2006.

Sources:

Ripple, J. Manatees and Dugongs of the World, Voyageur Press, 1999.

http://www.gbrmpa.gov.au/corp_site/info_services/publications/misc_pub/dugongs

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

http://www.hsus.org/marine_mammals/a_closer_look_at_marine_mammals/dugongs.html

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

http://www.theoi.com/Pontios/Seirenes.html