It is believed mermaid legends may have originated when sailors from a distance glimpsed dugongs swimming in the water, and mistook them for half-human/half-fish creatures.

Statistics
Dugongs grow up to 3m in length and weigh up to 400kg - as much as a cow!

Physical description
The smooth, greyish-brown skin is thick and very tough, slightly lighter in colour on the belly, and has a light scattering of fine hair. The front limbs are modified into 35-45cm-long flippers. Unlike the manatees, the tail of the dugong is "fluked", resembling that of whales and dolphins. The body is nearly cylindrical in shape, and is otherwise fairly featureless. The head is ill-defined, with no distinct neck separating it from the body. The upper lip is very well developed, and forms a U-shaped, flat, disc-like pad. Deeply cleft up the centre, this pad also has two ridges covered with large, stiff bristles. The sealable nostrils are perched on the tip of the muzzle, midway between the eyes and the upper lip. The upper incisors in males over 12 years of age develop into short sturdy tusks.

Distribution
They inhabit sea grass beds and shallow tropical waters throughout the Indo-Pacific region. Most of the world’s population of dugongs is now found in northern Australia between Shark Bay in Western Australia and Moreton Bay in Queensland.

Diet
Dugongs are sometimes called "sea cows", because they graze on seagrasses. These marine plants grow on a sandy sea floor in shallow, warm water. Dugongs eat large amounts, leaving behind feeding trails of bare sand and uprooted seagrass.

Behaviour
Dugongs swim using their whale-like fluked tail for propulsion and their front flippers for balance and turning. Their movements are often slow and graceful. Early explorers and sailors believed that they were mermaids because of their streamlined bodies and the large teats at the base of their flippers. They have a rounded head with small eyes and a large snout. The nostrils are at the top of the snout and, like mammals, dugongs must surface to breathe. However, unlike other aquatic mammals such as some whales, dolphins and porpoises, dugongs cannot hold their breath under water for very long. It is generally for only a few minutes, especially if they are swimming fast. Dugongs have poor eyesight but acute hearing. They find and grasp seagrass with the aid of coarse, sensitive bristles, which cover the upper lip of their large and fleshy snout. Small tusks can be seen in adult males and some old females. During the mating season, male dugongs use their tusks to fight each other.

Reproduction
Female dugongs give birth underwater to a single calf every three to seven years. Birth takes place in shallow water and the baby dugong is able to swim to the top of the water for its first breath. Calves are about 100 to 120cm long and weigh 20 to 30 kg at birth. They stay with the mother, drinking milk from her teats and following close-by until 18-24 months of age. Dugongs reach adult size between 9 and 17 years of age.

Conservation status
Their status is listed as Vulnerable. They are a protected species in Australia, only traditionally hunted by the Aborigines. Dugongs only live where there is seagrass, which is being destroyed by dredging and farm soil being washed into the sea, as well as pollution. Dugongs, like dolphins, are also accidental victims to large net fishing. On the Great Barrier Reef the dugong population in 1987 was approximately 3,500. In 4 years (1991) the population was halved to 1,700. Their naturally slow reproductive rate, long gestation period, and slow growth rate contribute to the fragility of the population. They can live for 70 years, but a dugong might reach the age of 17 years before breeding.

Best place to see
Shark Bay, Western Australia, has a relatively large population. Hervey Bay in Queensland also has them in numbers.