Dugong (thing)

It's not that they aren't related. The Order Sirenia has two Families and only four existing species. Three are manatees and the other is the dugong. While all three manatee species are of the Family Trichechidae—the West Indian manatee (T. manatus), the West African manatee (T. senegalensis), and the Amazonian manatee (T. inunguis); the sole surviving member of the Family Dugongidae is the dugong (Dugong dugon). Its only other Family member was Hydrodamalis gigas, called the Steller's Sea Cow which was hunted to extinction in the 1700s. Like manatees, they are often referred to as " sea cows" (a misnomer since the only true sea cow was H. gigas) and many think are the source (along with other psychological reasons) for many of the stories of mermaid sightings.

Details:
Adult length (including tail): 2.4-4 m (8-13 feet)
Adult length (flipper): 35-45 cm (14-18 inches)
Adult weight: 230-900 kg (500-1980 pounds)
Newborn length: 1-1.2 m (39.3-47.2 inches)
Newborn weight: 20-25 kg (44-71 pounds)

The dugong does look very similar to the manatee. This mammal has a streamlined body going from the head (no discernible neck) to a thickened, rounded torso, tapering down to a fluked tail similar to a whale (the manatee has no fluke). There are forelimbs modified into flippers which are used for turning and helping to gather food to its mouth (these lack the small vestigial nails on the ends that manatees have). Calves will use the flippers as a means of propulsion but the adults mainly use their powerful tail. The eyes are small and the dugong probably has poor eyesight. On the other hand, despite the small ear holes, it has excellent hearing. Its nostrils are able to close, helping it in its marine environment.

It has a tough greyish-brown hide that is somewhat lighter on the belly (calves are born more of a pale cream color and the skin darkens as they age) and has scattered hairs. It has a strong, cleft upper lip (less split than in manatees) and a down-turned mouth. There are coarse bristles on its snout that enable it to better find its diet of seagrass (dugongs also eat algae and crabs have been found in their stomachs—though the animal is classified as an herbivore). It's thought that their "grazing" helps promote new seagrass growth. They feed in shallow water usually about 1-5 m (3.2-16.4 feet) deep. As they feed, they "walk" using their flippers across the seagrass bed searching for the best food (they leave characteristically identifiable trails from foraging). When found, the dugong shakes the plants with its mouth to remove the sand and sediment before eating. They usually eat at night or when the tide is low and can consume up to 30 kg (66 pounds) of vegetation a day.

Unlike its extinct cousin, the dugong has teeth. They are flat, column-like cheek teeth that are rootless and are missing enamel. As the creature ages, they move forward and eventually fall out. They also have incisors; the front and lower ones are vestigial and not always there. The second uppers are tusk-like and in the males over 12 years protrude (they are usually hidden in the jaw in females). Not used for protection, these small " tusks" are used in male rivalries during mating season and occasionally some scars from these contests have been found on other dugongs. When in danger, they try to swim away to escape (calves hide behind their mothers for protection).

They tend to be slow swimmers and average about 10 km (6 miles) an hour. They can, if necessary go faster when in danger but only for short bursts. They cannot hold their breath for long periods of time and their short, shallow dives are usually no longer than 1-3 minutes. They make sounds similar to whistles, chirps, and bleats, though not often heard.

Dugongs are gregarious creatures and often live in herds, which in the past have reported as numbering into the hundreds. Due to declining numbers that is rare. More commonly, one finds groups not much larger than six. Occasionally they can be found single or in pairs, as well. Breeding can take place throughout the year. They have a long gestation period of 13-14 months and only give birth to one calf at a time. They hit sexual maturity between nine and fifteen years and give birth only every 3-7 years. Birth takes place in shallow water and the young must immediately swim to the surface for air. Though they can begin feeding on seagrass as early as three months, lactation lasts for eighteen. Throughout that time, the calf will stay close to its mother, even "clinging" to her back during feeding and resurfacing early on. Their life span is around 70 years.

Manatees exclusively reside in the Atlantic region and tend to favor freshwater rivers and coastal areas, mostly in the Caribbean-Atlantic region with one species near West Africa. The dugong is a more purely marine animal and is widely spread (and probably was once even more) being found in the Red Sea, along parts of eastern Africa, along coastal parts of India, the Malay peninsula, the Philippines, and northern Australia to New Guinea. They can also be found scattered throughout island areas in that range. They prefer somewhat shallow coastal waters where there is an abundance of sea grass and need a water temperature above 18° C (64.4° F).

While they are fairly widespread and it's thought the species numbers close to 100,000, most of the smaller "groupings" are in danger of disappearing in the near future. The larger populations will probably escape extinction for the time being. The largest population (70,000) can be found along the northern Australian coastal waters where the animal is offered some protection by law. The second largest can be found in the Red Sea (close to 6000) with around 4000 found between Somalia and Mozambique. The rest are in small populations that are declining rapidly—as are the for-now relatively stable ones.

Because of their size, there are few predators, though large sharks, killer whales, and saltwater crocodiles pose a threat. Man is also a threat. The animal has been killed for years as part of various aboriginal cultures for its meat (said to taste like veal). It has also been hunted for non-cultural reasons for meat, hides, oil (24-56 L or 6.3-14.7 gallons, per adult), and bones and teeth (used to make " artifacts"). Some Asian cultures use parts for "medicinal" use. Other dangers posed by man are getting caught in shark nets and collisions with boats. Slow breeding also makes it difficult to replenish numbers.

(Sources: www.ultimateungulate.com, http://animaldiversity.ummz.umich.edu/accounts/dugong/d._dugon$narrative.html, www.gbrmpa.gov.au/corp_site/info_services/publications/dugong/what_is_a_dugong.html, http://home.mira.net/~areadman/dugong.htm, http://home.t-online.de/home/rothauscher/dugong.htm)