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Dugongs

The large, slow-moving dugong (Dugong dugon) is found in 43 countries along the western Pacific and Indian Oceans (also known as the Indo-Pacific), with populations ranging from the coastal waters of East Africa and the Persian Gulf to Japan, the Philippines, and Australia. With approximately 85,000 animals, Australia has the highest dugong population.

Along with the manatee and the now-extinct Steller's Sea Cow, the dugong makes up the order Sirenia. The order's name is derived from the traditional belief that its members inspired the myths of sirens and mermaids. Somewhat less poetically, dugong and manatees are also referred to as sea cows.

Adult dugongs, both male and female, can grow to 11 feet or more in length, and may weigh well over 2,000 pounds. With their round heads and prominent snouts, dugongs look much like manatees, but their slate-gray skin is smoother and their shape is more stream-lined. Like dolphins, dugongs have pointed flippers, which they may use to "walk" along the sea bed when feeding, as well as fluke-shaped (split) tails. (This is in contrast to a manatee's tail, which is shaped like a rounded paddle.) Male dugongs begin to grow tusks between the ages of 12 and 15 years. If food is plentiful, the habitat protected, and predation low, dugongs may live more than 70 years.

Dugongs generally inhabit shallow marine areas—bays, channels, and inshore islands—where their food source, seagrass, is abundant. Surfacing every minute or two for air, the dugong forages on bottom vegetation, often leaving long, bare furrows in seagrass meadows. A thick, movable pad at the end of the dugong's broad, flat muzzle uproots whole plants and pushes the food into his mouth.

Dugongs are most often seen alone or in pairs, usually a mother and her calf, but they have been sighted in large herds of several hundred. Dugongs have multiple mating partners, and may breed year-round. Their mating behavior involves groups of male dugongs splashing, tail-thrashing, and lunging as they compete for a single female. Calves are born after a 12- to 14-month gestation period, and spend several years with their mother, even after weaning at 18 months. Both males and females reach sexual maturity at around 9 or 10 years.

Dugong vocalize underwater with squeaks and squeals, probably only for short-range communication. Calves have been observed bleating like lambs when frightened.

Dugongs are natural prey for sharks, killer whales, and crocodiles, but they are most vulnerable to human activities. Hunting has drastically reduced dugong populations in some areas. Although dugong are protected by law in most countries, aboriginal subsistence hunting is permitted in Northern Australia and Papua New Guinea. Currently, dugongs are threatened by oil spills, entanglement in fishing gear, shark and turtle nets, dynamite fishing, and the disruption of their feeding by boats. Dugong habitat is also under pressure from coastal development, pollution, and other degradation.