Conservation Status– Vulnerable
The dugong has a long cylindrical body. At the head end the body is rounded and at the tail end it tapers down to a flipper. The body is grey in colour with a sparse covering of short hairs. The colour of the skin may change throughout their life due to algae growing on the skin. Located just behind the head is a pair of flippers, one on each side of the body. Some dugongs have short tusks on their face.
The dugong can measure up to 3 metres (9.8 feet). The average weight for dugongs is 420kg (926lb). Sexual dimorphism is present in this species as females are larger than males.
The average dugong will live for 50 to 70 years. The oldest individual ever found was 73 years old.
The dugong is an omnivore. Almost their entire diet is made up of sea grass which they spend the majority of the day foraging for. In some areas they will also seek out invertebrates including sea squirts and jelly fish.
Dugongs walk on their flippers as they feed. They will sometimes pull up sea grass and arrange it in piles before eating all of it.
Dugongs survive by drinking fresh water. As such they need to live near the coast so they can go into estuaries to drink then return to the ocean so they can feed.
The dugongs are found in shallow coastal waters in the oceans from Africa around the coast of Asia to Vanuatu and then around the coast of Australia. All of the populations of dugongs are found near seagrass meadows. They are extremely common in protected bays where sea grass grows better.
Sexual maturity is achieved between 8 and 19 years old. Females can tell the male is sexually mature as his tusks erupt. Some dugong males have been seen to patrol a territory which they defend to make sure any females entering the territory will mate with him. Otherwise males are nomadic and many males will go to a female. These males will spend their time attempting to mate with the female with a few of them being successful.
It takes a year for the dugong to give birth after a successful mating occurs. The mother moves to the shallows to give birth to her calf which is light cream in colouration. The calf is already 1.2 metres long.
The baby will stay close to its mothers side. This will continue as she suckles for 14-18 months. The calf starts tasting sea grass soon after birth. Once it becomes sexually mature at 7-8 years old the calf finally leaves its mother.
The dugong is such a large animal that its only predators are orcas, saltwater crocodiles and sharks. Death from parasite attacks is one of the most common causes of death.
Some dugong packs undertake a migration throughout the winter. They will either move to warm bays or canals or to the Northern countries in their range near the equator. They will also migrate in large groups if the sea grass in the area lacks essential nutrients.
Dugongs can travel up to 20 km/ph over a short distance. Normally though they will cruise at 10 km/ph but they can move even slower if they are feeding.
To communicate dugongs use chirps, whistles and barks.
A dugong can remain underwater for up to 6 minutes. A more common amount of time though is 2 ½ minutes. When breathing they will sometimes rest on their tail and poke their head out of the water.
The legend of the mermaid is based upon sightings by sailors of dugongs.
Common names for the dugong include ‘sea cow,’ ’sea pig,’ and ‘sea camel.’ Their name comes from the Talagog name ‘dugong’ which come from the Malay term ‘duyung’ which means ‘lady of the sea.’
Top : By Julien Willem (original photograph), Papa Lima Whiskey (derivative edit) (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
Bottom : By Camille Ménard [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons