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DUGONG

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Taxonomy
Order: Sirenia
Family: Dugongidae
Genus: Dugong
Species: Dugong dugon
Common Names: Dugong, Sea Cow
Distribution: Tropical and sub-tropical zones of the Indo-Pacific Region.

Habitat
Dugongs inhabit sheltered, shallow, tropical waters where there are large expanses of seagrass meadows available to them. They can be found in herds of up to 100 but with a declining population these numbers are now rare. Small groups of 2 to 3 dugongs are more common.

Nature
Shy with a tendency to avoid humans and human habitation.

Morphology and Identification
Dugongs have a rounded head with small marble sized eyes and a large “fleshy” upper lip. Its two nostrils are located at the top of its snout and surface breathing is aided by the ability to curl up its top lip. Their skin is “blubbery”, similar to that of a whale, and has short thick hairs spread all over its body. More prominent and course bristles appear around the front of its mouth. The bristles on their mouth and tongue-tip help it to find and grasp seagrass.

Adult males and (some) older females have tusks. Male dugongs use these tusks to fight with during the mating season to prove their strength and also guard female partners. Dugongs swim by using their shovel shaped tail in an up and down dolphin-like movement whilst using their front flippers for balance and direction. The Dugong cannot hold its breath underwater for long and has to resurface for air more frequently than whales, dolphins and porpoises.

Although the Dugong has poor eyesight it has a very acute sense of hearing.
If circumstances allow, dugongs can live up to 70 years of age. Age can be determined by counting growth layers in their tusks.

Closest Relatives
The elephant, as opposed to dolphins and whales, is more closely related to the Dugong. Their closest living marine mammal relatives are the Manatees. The other closest marine relative was the Stella sea cow, which became extinct in the 1700’s.


Reproduction
Dugongs’ have a very slow population growth rate. Females conceive one calf every 3 to 7 years. Females don’t sexually mature until they are at least six years old. Males sexually mature at about 4 years of age. Dugongs give birth to only 1 calf at a time. Their calf usually weighs between 20-30kg and is between 1-1.2m long. Dugongs give birth in very shallow water (1m and less). This makes it easier for the newborn calf to reach the surface for its’ first breath of air. Calves lactate for a period of 14-18 months, even though they can feed on sea grass a couple of months after being born.

Diet
Dugongs feed only on seagrass located in shallow, sheltered tropical coastlines. They also feed on the algae growing on the seagrass. Dugongs are the only herbivorous sea mammals in the world.

Population/Size
Adult dugongs can grow up to 3 metres (10feet), and weigh 500 kilograms.
Australia has the largest concentrated population of dugongs left in the world. The Australian population was estimated, in 1991, to be 70,000 with approximately 12,500 in the Torres Straight region and 1,700 in the Great Barrier Reef region. The Arabian Gulf holds the next largest population of Dugongs, approximately 5,000.

Conservation/Trade
Dugongs are renowned for their tasty meat (which is likened to veal, beef and pork) and for the medicinal qualities of their oil. Dugongs are a protected specie in Australia with the exception of traditional hunting by Aboriginals and Torres Straight Islanders.
The major threats to their survival is the depletion and ruination of feeding grounds due to the high level of (farm) soil and pollution being washed into the sea. Dugongs are also victims to net fishing. Dugongs are listed on the IUCN red danger list as an endangered specie. They will become extinct if their protection is not enforced.