Dugongs live in the shallow waters of at least 37 countries and territories around the world. Throughout their range which runs from east Africa to Vanuatu between about 26° north and south of the Equator, dugongs are threatened by rising pollution from the land, coastal development, boat traffic, entanglement in fishing nets, and hunting and poaching for their meat and trophies.

live in the shallow waters of at least 37 countries and territories around the world. Throughout their range which runs from east Africa to Vanuatu between about 26° north and south of the Equator, dugongs are threatened by rising pollution from the land, coastal development, boat traffic, entanglement in fishing nets, and hunting and poaching for their meat and trophies.live in the shallow waters of at least 37 countries and territories around the world. Throughout their range which runs from east Africa to Vanuatu between about 26° north and south of the Equator, dugongs are threatened by rising pollution from the land, coastal development, boat traffic, entanglement in fishing nets, and hunting and poaching for their meat and trophies.

Geographic Range

Dugongs found discontinuously in coastal waters of east Africa from the Red Sea to northernmost South, northeastern Indian, along the Malay peninsula, around the northern coast of Australia to New Guinea and many of the island groups of the South Pacific. Range was greater in the past.Dugongs have already disappeared from some places including the waters off Mauritius, western Sri Lanka, the Maldives, Japan's Sakishima Shoto Islands, Hong Kong's Pearl River estuary, several islands in the Philippines and parts of Cambodia and Vietnam.

Although dugongs are found in the waters of many countries, nearly all of them except Australia are developing nations with limited capacity to contain impacts on dugongs within sustainable limits. Therefore, dugong conservation world-wide is largely dependent on Australian initiatives.

Habitat

Dugongs inhabit shallow, tropical marine coastal water and are more strictly marine than manatees.

Physical Description

Dugongs are born a pale cream color, but they darken with age to a deep slate gray dorsally and laterally. The short hair is sparsely distributed over the body, save the bristles on the muzzle. The skin is thick, tough and smooth. The front-limbs have evolved into flippers that are 35-45 cm long. These are used for propulsion by young, but the adults use the fluke-like tail for locomotion, using the flippers for steering. Despite its diet, the dugong ha s a relatively simple stomach. The muscular upper lip is cleft and protrudes over the down turned mouth. The lower lip and distal parts of the palate have horny pads used to grasp vegetation, which is then uprooted with the strong upper lip. The dental formula is 0/0 0/0 0/0 2-3/2-3, for a total of 10-14 teeth in adults. The molars are rootless, circular in cross-section and lack enamel. The premaxilla is enlarged and downturned, the nasal bones are absent, the braincase is small and the zygomatic arch is thick and deep. The bones of the skeleton are pachyostotic, which is to say extremely thickened and dense. Adults range in length from 2.4 to 4 m. Sexual dimorphism is either absent or females may slightly outsize males.

Food Habits

Dugongs are aquatic herbivores and feed on the phangerogamous sea grasses of the families Potomogetonaceae and Hydrocharitaceae. Also reported to occasionally eat algae, and crabs have been found in the stomachs of dugongs.

Economic Importance for Humans: Positive

Dugongs are hunted throughout their range for meat,which has been likened to veal. They are also hunted for oil, hides for leather, and for their bones and teeth, which are made into ivory artifacts and charcoal for sugar refining. Some Asian cultures prize dugong products for medicinal purposes.

Conservation Status

Dugongs are listed as endangered under the Endangered Species Act of the U.S.A. and as vulnerable by the IUCN. All populations are in CITES Appendix I except the Australian populations, which are in Appendix II.

Other Comments

Dugongs have a good fossil record going back to Eocene terrestrial ancestors.

Contributors

David L. Fox (author), University of Michigan.

References

• Husar, S. L. 1978. Dugong dugon. Mammalian Species Account No. 88. American Society of Mammalogists, 7 pp.

• Nowak, R. M. 1991. Walker's Mammals of the World. The Johns Hopkins University Press, Baltimore.