The dugong (Dugong dugon) is the only one of four species of sirenian that is found in Australian waters. The dugong is a mammal and so breathes air through two nostrils on the top of its snout, is warm blooded, and gives birth to live young that closely resemble the adults. The young are suckled on milk produced by the mother (or 'cow'). The dugong resembles the whales and dolphins in shape, having a wide and powerful horizontal tail and two 'pectoral' or side fins. There is no dorsal fin. They are quite stocky compared with dolphins or small whales, however, and relatively slow in their movements. They are strict herbivores, foraging along the bottom in shallow coastal waters, usually grazing on beds of seagrass. This and their appearance has earned them the name "sea cows". Like the other marine mammals, the ancestors of the dugong once lived on land but went back to the sea many millions of years ago. Now the dugong leads an entirely marine existence.

• To be warm blooded, breathe air with lungs, give birth to and suckle live young like most other mammals.
• To live in very shallow coastal waters in the tropics and sub-tropics of the Indo-Pacific and eastern Africa.
• To have a layer of blubber under the skin but no fur. The skin has a small number of short bristly hairs but no scales.
• To have a streamlined but robust body with a broad whale-like tail and two paddle shaped flippers.
• To be a vegetarian with molar teeth for grinding up seagrass.
• To spend your entire life in the oceans.

Sea cows.

Dugong look like stocky, robust small whales. They are streamlined and have a broad and powerful horizontal tail with a notch in its centre and two short thick "pectoral" fins. They have no dorsal fin. They have a small head which is continuous with the body. They have small eyes and two nostrils that have flaps to seal them shut when they are underwater. The nostrils are on the end and top of their muzzle. The muzzle is blunt and bends downwards so that the mouth opens down for grazing on the bottom. They have small incisor and canine teeth but large molars for grinding up seagrass. They are grey to bronzy brown in colour, usually lighter on the belly. Calves are a pale creamy colour. Dugong are usually either solitary or found in small loose herds of 6 to 30 animals that move slowly around together. Herds of up to several hundred animals have been reported.

Dugong inhabit shallow sheltered waters in tropical and sub-tropical coastal regions, particularly in bays. They have even been found up rivers!. They occur in pockets right around the northern half of Australia and up through the western Pacific Islands, Indonesia and South East Asia. They are also found along the coast of eastern Africa, in the Red Sea and Persian Gulf, and along the west coast of India and Sri Lanka. The females seem to inhabit one particular area while males may wander from one area to another in search of mates. They don't appear to be territorial, groups often meeting and coming together without any antagonism. They do not migrate.

Dugong almost exclusively eat seagrass that grows in thick beds in sheltered shallow coastal waters. The seagrass is often in such shallow water that the dugong can only eat it at high tide. The dugong's position in the food chain is much like any large grazing mammal - they eat only vegetable matter but are prayed on by very few other animals and so are near the top of a very simple food chain. The dugong's teeth reflect its diet being very similar to that of a domestic cow. They have lower jaw incisors that snip off the seagrass which is than chewed up by large powerful molars.

Dugong have very few natural predators. Although they are sometimes attacked by large sharks, they gather in herds and can defend themselves against most attacks, the large males protecting the females and calves. Their main predators are people and they are still subsistence and commercially hunted for food in many areas.

Not a great deal is known about dugong reproduction. The age at which female dugong can reproduce is not certain, but it may be as much as 7 to 10 years. Gestation is thought to be 13 to 14 months after which a single calf is born. There seems to be some reproductive activity all year round but calving tends to peak in June and September. It is not known how long they live.

Dugong tend to live in small herds of up to 30 individuals although much larger groups are sometimes seen. Solitary animals are also found and may be males wandering in search of mates.

Dugong are very benign and peaceful animals and coexist in many areas with people. Most interactions, however, are harmful, dugong being the targets of commercial and subsistence hunting in many parts of their range. They are also prone to being struck and killed by motor boats as well as being caught and drowned in fishing nets. There have also been deaths of dugong associated with the destruction of their habitat, especially anything that affects their food, seagrass beds. Changes to their food supply may be direct by the dredging of bays, or indirect, such as when farm chemicals are washed down rivers in high concentrations by heavy rain, killing seagrass in shallow coastal areas. Not a great deal is known about how many dugong there are around the world, but there is evidence that numbers are declining in general and they have disappeared from some areas entirely.