Dugong is the common name for a large, herbivorous, fully aquatic marine mammal, Dugong dugon, characterized by gray-colored, nearly hairless skin, paddle-like forelimbs, no hind limbs, a fluke-like (forked) tail, a sharply downturned snout, and tusks. The dugong is only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller’s sea cow (Hydrodamalis gigas), was hunted to extinction in the eighteenth century. The dugong is found in Indo-Pacific waters from eastern Africa to southeast Asia.

Dugongs are part of the order Sirenia along with manatees, both of which are sometimes known as “sea cows” for their grazing of vegetation. The dugong is heavily dependent on seagrasses for subsistence. A “cultivation grazer,” it feeds on the seagrass in a manner that actually promotes regrowth of the seagrass, though aerating the sea floor and increasing the amount of organic matter in the area.

The dugong has been hunted for thousands of years for its meat, fat, oil, hides, and bones. However, their significance to humans goes beyond such physical values to cultural significance for the indigenous peoples throughout the dugong’s range. The dugong also has an ecological function as part of marine food chains, although its large size means adults have few predators, these being such as sharks, killer whales, and saltwater crocodiles.

Despite these values, the dugong faces many risks from such anthropogenic (human caused) factors as habitat destruction, pollution, hunting, fishing-related fatalities, and collisions with boats and propellers as they surface for air. With its long lifespan and slow rate of reproduction, the dugong is especially vulnerable to these types of exploitation. The dugong’s current distribution is reduced and disjunct, and many populations are close to extinction. The IUCN lists the dugong as a species vulnerable to extinction, while the Convention on International Trade in Endangered Species limits or bans the trade of derived products based on the population involved. The dugong population is predicted to enter a steep decline. However, many scientists are working to prevent this potentially cataclysmic blow to the entire dugong population. Currently, this effort is proving futile, as the dugong population is not showing any increased population numbers.

Overview and description

The dugong is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. Sirenians are one of four groups of marine mammals, the others being cetaceans (whales, dolphins, and porpoises), sea otters, and pinnipeds (walruses, earless seals, and eared seals). The sirenians and cetaceans are completely aquatic, while pinnipeds spend considerable time on land, including giving birth and raising their young, and sea otters can mate and raise their young entirely at sea. Sirenia is thought to have evolved from four-legged land mammals over 60 million years ago, with the closest living relatives being the Proboscidea (elephants) and Hyracoidea (hyraxes) (Domning 1994). The dugong is the only strictly-marine herbivorous sirenian, as all species of manatee utilize freshwater to some degree.

Like all modern sirenians, the dugong has a fusiform body with no dorsal fin or hindlimbs, instead possessing paddle-like forelimbs used to maneuver itself. The main visual difference between manatees and dugongs are the tails. A manatee tail is paddle-shaped, while a dugong tail is forked, similar in shape to that of a whale of dolphin. The paddle-like forelimbs aid in movement and feeding, while its fluked tail provides locomotion through vertical movement. The dugong also possesses a unique skull and teeth (Myers 2002).

Unlike the manatees, the dugong’s teeth do not continually grow back via horizontal tooth replacement (Self-Sullivan 2007). The dugong has two incisors (tusks) which grow posteriorly until puberty, after which they first erupt in males. The female’s tusks continue to grow posteriorly, often not externally evident, but sometimes erupting later in life after reaching the base of the premaxilla (Marsh 1989).

Like other sirenians, the dugong experiences pachyostosis, a condition in which the ribs and other long bones are unusually solid and contain little or no marrow. These heavy bones, which are among the densest in the animal kingdom (Waller et al. 1996), may act as a ballast to help keep sirenians suspended slightly below the water’s surface (Myers 2000).

Dugongs are generally smaller than manatees (with the exception of the Amazonian manatee), reaching an average adult length of 2.7 meters (8.9 feet]]) and a weight of 250 to 300 kilograms (550 to 660 pounds]) (IFAW 2008). An adult’s length rarely exceeds 3 meters, and females tend to be larger than males (Marsh 1989). The largest known dugong was an exceptional female landed off the Saurashtra coast of west India, measuring 4.03 meters (13.3 feet) and weighing 1,018 kilograms (2,240 pounds) (Wood 1982).

The word “dugong” derives from the Tagalog term dugong, which was in turn adopted from the Malay duyung, both meaning “lady of the sea” (Winger 2000). Other common local names include “sea cow,” “sea pig,” and “sea camel” (Reeves et al. 2002).

The dugong was first classified by Müller in 1776 as Trichechus dugon (PD 2008a), a member of the manatee genus previously defined by Linnaeus (PD 2008b). It was later assigned as the type species of Dugong by Lacépède (PD 2008c) and further classified within its own family by Gray (PD 2008d), and subfamily by Simpson (PD 2008e).

Distribution

The dugong is the only sirenian in its range, which spans the waters of at least 37 countries throughout the Indo-Pacific, from Africa to the Philippines and the South China and East China Seas, where sea grasses are found (Marsh et al. 2002; Grzimek et al. 2004). However, the majority of dugongs live in the northern waters of Australia between Shark Bay and Moreton Bay (Lawler et al. 2002).

The dugong is heavily dependent on seagrasses for subsistence and is thus restricted to the coastal habitats where they grow, with the largest dugong concentrations typically occurring in wide, shallow, protected areas such as bays, mangrove channels, and the lee sides of large inshore islands (Marsh et al. 2002).

Remaining populations of dugong are greatly reduced, although they once covered all of the tropical South Pacific and Indian Oceans. Their historic range is believed to correspond to that of certain seagrasses (Marsh et al. 2002). Groups of 10,000 or more are present on the Great Barrier Reef of Australia, at Shark Bay, and in Torres Strait south of New Guinea. Before 1970, it is thought that large populations were also present in Mozambique and coastal Kenya, but these have dwindled. Palau also has a small population.

Moreton Bay in Brisbane, Australia is one of many homes to the dugong because it contains clean, clear water at the appropriate depth ranges, suitable food, and access to the sea for warmth. Although strong tidal currents affect the exact times and durations of each visit to the bay, the dugong return for protection from large sharks. This area is very important to the future of the dugong—it is a 200 km stretch of high density human habitation and recreation, with ease of access to study and learn how to best protect the remaining herds.

A small number of dugongs are also found in the Straits of Johor, (which separates Johor in Malaysia and Singapore), in the Philippine provinces of Palawan, Romblon, Guimaras, Arabian Sea along Pakistan, and Davao Oriental, and in the Red Sea in Egypt provinces Marsa Alam at Marsa Abu Dabbab.

An endangered population of 50 or fewer dugongs survives around Okinawa (Galvin).

Feeding, reproduction, and life cycle

Dugongs are particular about their diets, with certain “fields” of sea-grass cropped. Dugongs commonly are referred to as “sea cows” because their diet consists mainly of the leaves and roots of sea-grass. An adult eats about 30 kilograms of seagrass each day (EPA 2007).

Unlike manatees, dugongs are exclusively benthic feeders. The muscular snouts of dugongs are more dramatically tapered than those of manatees. Their primary feeding mechanism is uprooting sea-grass by digging furrows in the seafloor with their snouts. Dugons are known as “cultivation grazers,” since they feed in a manner that promotes growth of the seagrass; pulling out the seagrass in a way that aerates the sea floor and increases the amount of organic matter in the area, therefore promoting regrowth of the seagrass (EPA 2007.

Dugongs in Moreton Bay, Australia are omnivorous since they choose to eat invertebrates such as polychaetes when the supply of their choice grasses decreases (Berta et al. 2006).

They will also go to any fresh water sources for drinking. Without these fresh water sources, many would not survive. The amount of these fresh water sources, however, is beginning to decline.

Because of their large size, they do not have many natural predators. These include sharks, killer whales, and saltwater crocodiles.

During the winter, a few herds of dugongs will move to warmer places in the northern countries, such as bays and canals. Dugongs also live in warmer waters of many other countries near the equator.

Gestation in the dugong lasts around 13 months, and results in the birth of a single young. The calf is not fully weaned for a further two years, and does not become sexually mature until the age of 8 to 18, longer than in most other mammals. They give birth to a calf only once every three to five years, depending on the suitability of the food source (EPA 2007). As a result, despite the longevity of the dugong, which may live for seventy years or more (EPA 2007), females give birth only a few times during their life, and invest considerable parental care in their young (Anderson 1984).

The primary social unit is the female with her calf. Dugongs may form large foraging herds, from tens to hundreds of individuals (Grzimek et al. 2004).

Importance to humans

There is a 5000-year old wall painting of a dugong, apparently drawn by neolithic peoples, found in Tambun Cave of Ipoh city in the state of Perak, Malaysia. This dugong image, together with some thirty other images, were painted using haematite, a type of red coloring easily available in the area to ancestors of the Orang Asli living in and around Tambun.

It is possible that the dugong or manatee could be source for the origin of the mermaid myth. When seen from above, the top half of a dugong or manatee can appear like that of a human woman. Coupled with the tail fin, this produced an image of what mariners often mistook for an aquatic human.

During the Renaissance and the Baroque eras, dugongs were often exhibited in wunderkammers. They were also presented as Fiji mermaids in sideshows.

The dugong is referred to in the Bible by the phrase “sea cow” in several places in Exodus (for example, 25:5 and 26:14) and in Numbers. Dugong hides may have been used in the construction of the Tabernacle, if dugong is an accurate translation of the biblical animal tachash.

Worldwide, only a few dugongs are held in captivity, including in Japan, Singapore, and Australia.

Dugons face a number of risks, from hunting, habitat destruction, and collisions. Dugongs are hunted for food throughout their wildlife range, usually for their meat, blubber, and hides. Also, the seagrass beds which the dugong depend on for food are threatened by eutrophication caused by agricultural and industrial runoff. Due to their shallow water feeding habits and surfacing for air, dugong are frequently injured or killed by collisions with motor vessels.

Around the waters of Papua New Guinea, natives have been known for hunting dugongs. However, they also hunt dugong’s predators, such as sharks.

For Isaac Asimov’s detective, Elijah Baley, it’s been two long years since he’s set forth on an interstellar adventure, and though he once shuddered at the thought of hyperspace travel, he’s now itching to once again do some planet hopping.

However, for Asimov enthusiasts, the wait was a great deal more labored. There is a span of twenty-six years between The Naked Sun (1957) and The Robots of Dawn (1983), the next full-length sci-fi/mystery whodunit featuring Baley and his robot partner Daneel Olivaw. Patient fans’ appetites were whetted with a Baley and Daneel short story that appeared in a 1972 issue of Analog Science Fiction and Fact called, “Mirror Image.” Asimov said the general reaction was, “Thanks, but we wanted another novel.” Let’s take a look and see if it was worth nearly three decades of yearning.

Baley has been promoted to a higher C-7 rating that allows him to go outside the concealed city and is attempting to begin again, so to speak, with a select group of agoraphobic humans—experiencing air, dirt, and other dizzying aspects of nature that in this future Earth is mostly patrolled by robots. His nineteen-year-old son, Bentley, is on this particular exploit and is also planning to go into space. Baley’s wife, Jessie, who played an important role in the first novel, is only mentioned in passing—she is much more comfortable staying within the hive. As Baley returns after one such jaunt outside, he reflects on the caves of steel:

Baley felt his breath drawn in tremulously and he gladdened in the realization that he was home and safe with the known and knowable. That was what always happened. Again he had accepted the City as the womb and moved back into it with glad relief. He knew that such a womb was something from which humanity must emerge and be born.

Baley is now a bona fide hero after a hyperwave dramatization (kind of like a movie of the week streamed universe wide) recounted, with great embellishment, the events of his last murder case on the planet Solaria. And, while cracking that case raised respect for Earthling’s in the eyes of the other planets and gained him an upgrade in professional ranking, it also netted the ire of his superiors by unveiling the ineptness of his own government. So, when Baley’s friend—the 165-year-old Dr. Han Fastolfe—requests assistance on Aurora, the largest of all Spacer worlds, Baley goes knowing that if he fails, his bosses will be in a good position to place the blame squarely on him.

Teaming once again with Daneel, a robot that is nearly indistinguishable from a human, they begin investigating the roboticide (term coined by Baley and Daneel on the journey to Aurora) of Jander Panell, the second humaniform ever designed. Jander’s mind was destroyed in what Aurorans call a “mental freeze-out.”

Like the murder case of The Naked Sun, there is only one logical explanation, and, in this outing, that explanation is Fastolfe committed the crime because he alone—as the leading theoretical scientist—has the knowledge to “murder” Jander. Fastolfe maintains that “a spontaneous event in the positronic brain paths” caused the freeze-out, then just as quickly admits it’s highly unlikely.

As Baley prods and pokes for information, it’s apparent that not everyone is an admirer of the celebrity investigator. Fearing his life is in danger, he’s surrounded by a large contingent of robots for his safety. And yet, despite all their efforts, it’s somehow missed that an airlift he’s riding in has been sabotaged:

The airfoil came down with a bump and a short, harsh, scraping noise. The doors flew open, one on either side, and then closed with a soft, sighing noise. At once, the robots were gone. Having come to their decision, there was no hesitation and they moved with a speed that human beings could not duplicate.

Asimov’s 1983 tech includes an “Astrosimulator” that creates the sensation of being in space, a “Spicer” that delivers a dozen different seasonings at the flip of a wrist, and the “Personal,” which is a Trek-like holodeck bathroom, where Baley’s senses are enlivened when washing his hands under a replicated image of a running waterfall, complete with soap. Nothing earth shattering, though the “Astrosimulator” is very much with us in the form of virtual reality goggles, and I, for one, am still longing for the holodeck.

In the hyperwave dramatization, it’s implied that Baley had an affair of sorts with Gladia Delmarre, the widow of the murder victim in Sun. She conveniently returns, having relocated to Aurora, and, you guessed it, is involved with the erased robot…Asimov is anything but subtle.

More surprising is the improvement in Asimov’s handling of female characters—feminism happened and Asimov must have been paying attention because, compared with the last adventure, the Gladia of Robots is more three-dimensional, operating on an intellectual level with Baley and carrying the secret of a relationship with the “murdered” Jander. Despite the advancement, the female voices, even if technically interesting, continue to have a tendency to be clumsy—like Gladia’s dialogue struggling through some inelegantly wrought emoting and embarrassingly touching on orgasms and masturbation.

All that aside, when Asimov switches back to the future of mankind, expressing the need to vacate this planet and move out among the stars (as esteemed scientist Stephen Hawking has recently stated), it’s essential reading. Almost like Humanity 101.

In The Robots of Dawn, Asimov begins connecting his universe by mentioning Dr. Susan Calvin, a heroine of his classic I, Robot (1950) collection. This technique would be further utilized in the fourth novel, Robots and Empire, where he began connecting his Robot books to his equally acclaimed Foundation series, and Daneel goes on to become the focal point, where it’s gradually revealed he’s guiding humankind toward idealized goals.

Fans of the first two novels and the short story “Mirror Image” will be much rewarded by The Robots of Dawn’s more mature setting, though I wouldn’t necessarily recommend the uninitiated dive-in here. The Baley/Daneel relationship—the heart of this series—is best viewed from the beginning with The Caves of Steel (1954), when these two opposites meet, not knowing that their partnership would change the future.

Former Russian president Boris Yeltsin got so drunk during a visit to Washington that he was found standing outside the White House in his underpants trying to hail a cab to go and buy a pizza.

The following night he was mistaken for a drunken intruder when he was discovered stumbling around the basement of his guest house by secret service agents.

The drunken behaviour of Yeltsin, who was known for his fondness for vodka and died two years ago aged 76, were revealed by former US president Bill Clinton.

Clinton, who is no stranger to indiscretions of his own, sat down with historian Taylor Branch to give an “oral history” of his presidency.

The results of 70 taped interviews between Clinton and Branch, who were former flatmates from the 1970s, is a new book “The Clinton Tapes: Wrestling History with the President.”

Branch, a Pulitzer prize winning writer, was chosen by Clinton to be the unofficial historian of his eight years in power.

He taped all the interviews with Clinton who in 1998 survived a call for impeachment over his affair with White House intern Monica Lewinsky.

His relationship with Lewinsky is the one area that Clinton does not expand on during his taped conversations with 62 year old Branch.

Branch said Clinton told him he “just cracked” under political and personal pressure.

The book also details an “explosive” row between Clinton and Al Gore after the vice president lost the 2000 election campaign to George W Bush.

According to excerpts of the book published in USA Today newspaper, Clinton told Branch they had a heated two hour discussion in which Gore said the president’s scandalous behaviour had cost him the election.

The book reveals that Yeltsin’s drinking binge while staying at Blair House, the guest accommodation used by visiting dignitaries in 1995, almost ended in an international incident.

Mr Clinton told how he was briefed by secret service after they found Yeltsin standing outside the building dressed in his underwear trying to hail a taxi.

In a slurred speech he told the agents he wanted a pizza.

The following night he eluded his Russian bodyguards to climb out of Blair House into the basement where he was initially mistaken for an intruder.

The 707 page book, which is published next week,was sent to Clinton to proof read.

Branch said he did not ask for any alterations.

Other subjects covered included Clinton’s view of George Bush, describing him as “unqualified” to be president.

Despite the growing awareness, bullying is still common in schools these days. Some kids are bullied and some bully others. But, as a new study finds, kids with autism spectrum disorder (ASD) may have an even harder time with bullying, being many times more likely than their neurotypical siblings to have experienced it in their lifetimes. Even more disturbing, autistic kids may be intentionally triggered into having meltdowns by bullies who know how to push the right buttons.

The new study, from Kennedy Krieger’s Interactive Autism Network, surveyed families with autistic and non-autistic siblings from all over the country, asking about their experience with bullying in the past and present.

Almost two-thirds of autistic children had been bullied at some point in their lives, and they were three times more likely than neurotypical kids to be bullied in the past three months. This was even true for home-schooled autistic children, who were sometimes educated at home precisely because of the bullying issue. “After a horrible year in 3rd grade,” said one mother, “where he was clinically diagnosed as depressed (he has always been anxious), I pulled my son out of public school and am homeschooling him this year. He is doing much, much better without the constant name calling and being singled out for his ‘weird’ behaviors!”

The three most common types of bullying were verbal, or, in other words, psychological in nature: “being teased, picked on, or made fun of” (73%); “being ignored or left out of things on purpose” (51%), and “being called bad names” (47%). But almost a third of autistic children also experienced physical bullying – being shoved, pushed, slapped, hit, or kicked.

Even more disturbing was the fact that over half of the autistic children surveyed had experienced intentional triggering of meltdowns or had been “provoked into fighting back.” One mother said, “Often kids try to upset her because they find it funny when she gets upset and cries. She is overly emotional, and they seem to get a kick out of this.”

Bullying was most pronounced in regular public schools (43%), but better in special education public schools (30%), and lowest in regular private schools and special education private schools (28% and 18%, respectively).

Oddly, when the team broke down bullying as a function of the different types of autism (Asperger syndrome, autism, and “other ASD”), they found that children with Asperger syndrome were actually the most bullied group. Since Asperger is a higher functioning form of autism, this is peculiar. The researchers aren’t sure why this is true, but one hypothesis is that it’s because people with Asperger are often highly intelligent but can still have considerable social deficits, which makes them, in effect, the “perfect target.”

Children with autism are also more likely to bully others: About 20% of kids with autism bullied (vs. only 8% of neurotypical children). According to the report, many of these kids may actually be both bully and victim, which is somewhat more common in children with developmental or emotional problems. Children with ASD who bully may do it unintentionally. “My son doesn’t realize he is bullying,” said one parent. “He is trying to get other kids to pay attention to him so he does it by grabbing their ball away from them or getting ‘in their face’ when they say to stop.” Another parent said, “Our boy… may take an object from another child or scream when unhappy but any purposeful cruelty, he would never do.”

And for autistic children who are being bullied and bully in return, they may not have the social skills to avoid or to get themselves out of the situation. According to the report, “Unlike victims who are more passive, bully-victims insult their tormentors or otherwise try to fight back in a way that only makes the situation worse.”

Finally, a critical issue that the report brings up is whether bullying may cause people with autism to develop more mental health problems as a result. Some studies have suggested that any child who is bullied has a greater risk for everything from headaches and stomachaches to anxiety, depression, and suicide.

Parents, caregivers and schools work hard to help kids with autism gain social skills and emotional tools, and the idea that bullying could negate this work is disheartening. “Bullying can undo all our efforts,” Connie Anderson, of the Interactive Autism Network, told NPR. “I think that’s the most devastating thing about it. Children on the spectrum can be anxious anyway. This can just put them over the top and undo all the good that everyone’s trying to do.”