With its rotund body, fluked tail and shy temperament, it's easy to imagine the dugong inspiring the mermaid legend. This gentle mammal's body is beautifully streamlined for marine life and it glides effortlessly through seagrass meadows, but is just as elusive.
Poor eyesight means the dugong is reliant on sensitive bristles along its pig-like snout to locate the grasses on which it dines, and it can dive for up to 10 minutes at a time while grazing. Although generally travelling at a leisurely rate of 10 kilometres per hour, the dugong can accelerate to 22 kilometres per hour in short bursts.
The dugong's hearing is acute and, even without vocal chords, it can produce squeaks and pips to communicate with its young. Offspring may remain with their mothers for up to two years and individuals are sometimes found in loosely structured groups of up to a dozen or so animals.
The vast seagrass plains of the northern Great Barrier Reef are home to one of the largest populations of dugongs in the world. But even here, commercial gill nets that drape like curtains pose a threat of drowning.
Dugong distribution has declined around the world and the population living on the Great Barrier Reef may be one of the largest remaining.
Wherever they survive, dugongs play an important role in maintaining coastal ecosystems. Their constant browsing of seagrass encourages regrowth - ensuring critical habitat and feeding sites for a host of other marine species, including turtles, dolphins and sawfish. So, healthy dugongs means healthy seagrass and broader Great Barrier Reef health.
Dugongs can live for about 70 years but population growth is slow. A female is 10 before she has her first calf and will only reproduce every three to seven years, caring for a single calf for two years or more. So even under optimal conditions, dugong populations can only ever increase by 5% a year. When under stress, females respond by producing fewer young, further stalling population growth.
Marine pollution Pesticide and nutrient run-off into the Great Barrier Reef degrades water quality and can smother the seagrasses on which dugongs depend. Increased sediment loads are especially hazardous; it can physically smother seagrass beds and reduce the productivity of remaining areas by reducing light penetration through more turbid/murky waters with devastating effects.
Bycatch Dugongs not only become entangled in fishing nets and drown, as unintended bycatch; they also suffer boat strikes and can choke on marine debris left behind by fishers. Discarded ‘ghost nets’ and fishing gear are especially hazardous and can entrap unwitting animals.
Global warming Being so dependent on shallow coastal waters leaves dugongs extremely vulnerable to global warming, especially rising sea levels. Extreme weather events, of which we are likely to see more, rob the dugong of critical habitat. Large-scale flooding caused by cyclones and extreme rainfall events also increases run-off from land, which can damage or pollute seagrass beds and was responsible for the highest record of dugong strandings following the Queensland 2010/11 summer of floods
You can help right now by contributing to WWF-Australia's . We're in negotiations to buy the last full-time commercial gill net in operation in the northern Great Barrier Reef - a net stretching 600 metres that poses a deadly threat to dugongs.
Taking this net out will create a 385-square-kilometre haven for dugongs in Princess Charlotte Bay. It's also the vital first step in achieving our dream of a 85,000 sq km refuge - an area bigger than Tasmania - that would stretch from Cape Flattery to the Torres Strait and help protect scores of other marine creatures.
The northern Great Barrier Reef is a stronghold for dugongs, which are threatened all around the world. On the east coast of Queensland, we estimate that each year commercial gillnetting entangles around 50 of these majestic animals, so it's a significant threat to declining populations. With your help, WWF-Australia can ensure that the Princess Charlotte Bay Special Management Area is a truly special area for dugongs.