Dugong

Dugong
Conservation status
Vulnerable
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Sirenia
Family:	Dugongidae Gray, 1821
Subfamily:	Dugonginae Gray, 1821
Genus:	Dugong Lacépède, 1799
Species:	D. dugon
Binomial name
Dugong dugon (Müller, 1776)

Dugongs (Dugong dugon) are the smallest members of the order Sirenia (which also includes the manatees and Steller's Sea Cow), with adults generally growing to less than 3 meters long. The name dugong originated from the Malay language duyung meaning lady of the sea or mermaid. They inhabit shallow waters in the Indo-Pacific, and feed on sea grass. They also have a long life span and slow breeding rate, which results in being susceptible to threats.

Distribution

Dugong

Remaining populations of dugong are greatly reduced, although they once covered all of the tropical South Pacific and Indian Oceans. Groups of 10,000 or more are present on the Great Barrier Reef of Australia, at Shark Bay, and in Torres Strait south of New Guinea. Before 1970, it is thought that large populations were also present in Mozambique and coastal Kenya, but these have dwindled. Palau also has a small population. On January 22, 2003, an individual was found (weight 300 kg, length 2 m) off the coast of Tanzania.

Moreton Bay, a large bay on the eastern coast of Australia, is one of many homes to the dugong because it contains clean and clear water at the appropriate depth ranges and suitable food. Access to the sea for warmth is possible and, although strong tidal currents affect the exact times and durations of each visit, the dugong return to the bay for protection from large sharks. This area is very important to the future of the dugong - it is a 200km stretch of high density human habitation, and recreation, with ease of access to study and learn how to best protect the remaining herds. The images show typical dugong habitat and travel paths.

Typical dugong Feeding area in Moreton Bay

File:MoretonIslandSouthernTip.jpg

Passage to the warmer sea around the southern tip of Moreton Island

A small number of dugongs are also found in the Straits of Johor, (which separates Johor in Malaysia and Singapore), in the Philippine provinces of Palawan, Romblon, Guimaras, and Davao Oriental, and in the Red Sea near Egypt.

The remaining dugongs in the Persian Gulf were reportedly further endangered by repeated U.S.-Iraq conflicts, because of the Gulf Wars, during which large oil spills occurred as a result of the conflicts. The current population and status of Persian Gulf dugongs are currently not well known.

Feeding

Dugongs are particular about their diets, with certain 'fields' of sea-grass cropped. Dugongs are referred to as 'sea cows' because of their diet eating sea-grass.

Migration

During winter, only a few packs of the Dugongs move to warmer places in the northern countries.

Dangers

Dugong are hunted for food throughout their range.

The seagrass beds upon which dugong depend are threatened by eutrophication caused by agricultural and industrial runoff.

Because they feed in shallow water dugong are frequently injured or killed by collisions with motor vessels.

The US and Japanese government want to build a new base on a coral reef close to Henoko, in Nago prefecture, Okinawa. But the plan generated strong protests from Okinawans who are concerned that the local environment, home to the dugong, would be ruined.

Dugongs can also be killed by rubbish including plastic bags which are often mistaken as jelly fish.

References

• Template:IUCN2006 Database entry includes a lengthy justification of why this species is vulnerable
• Shoshani, J. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 92. ISBN 978-0-8018-8221-0. OCLC 62265494.

Also see

• Sirenia
• Evolution of sirenians

External links

• images and movies of the dugong (Dugong dugon)
• Roberto Sozzani's Encounter with Dugongs
• UNEP Dugong Action Plan
• Sirenian International
• underwater encounter with a dugong
• tribute to the dugong on Weebls-Stuff
• Information on Dugong Dugon