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118-514: It was named after the dugongs that were once abundant in the area, although they have since become regionally extinct. It is the smaller of the two islands in the Eagle Islands group on the western side of the atoll and forms part of the Chagos Archipelago strict nature reserve . It has been identified as an Important Bird Area by BirdLife International because of its significance as

236-566: A monophyletic group with hyraxes and the aardvark , one of the earliest offshoots of eutherians . The fossil record shows sirenians appearing in the Eocene , where they most likely lived in the Tethys Ocean . The two extant families of sirenians are thought to have diverged in the mid-Eocene, after which the dugongs and their closest relative, the Steller's sea cow , split off from a common ancestor in

354-438: A muscular hydrostat , a biological structure that relies on muscular pressure and muscle contractions to manipulate and move food. The manatee uses its large upper perioral bristles to carry out a grasping motion: it performs a flare that tightens the muscular hydrostat while the large upper bristles get pushed out and the lower jaw drops and sweeps the vegetation in by closing. The primary bristles used for vegetation ingestion are

472-551: A petrosal bone was found in Tunisia, dating back to approximately the same time as Prorastomus . This is the oldest sirenian fossil to be found in Africa and supports molecular data suggesting that sirenians may have originated in Africa. Prorastomidae and Protosirenidae , the earliest sirenian families , consisted of pig-like amphibious creatures who died out at the end of the Eocene. With

590-514: A breeding site for brown noddies , of which 11,500 pairs were recorded in a 2004 survey. The whole shore of this island and some of the interior can be explored through Google Street View . 06°14′08″S 71°17′40″E  /  6.23556°S 71.29444°E  / -6.23556; 71.29444 This British Indian Ocean Territory location article is a stub . You can help Misplaced Pages by expanding it . Dugong The dugong ( / ˈ d ( j ) uː ɡ ɒ ŋ / ; Dugong dugon )

708-415: A certain range their entire lives. Large numbers often move together from one area to another. It is thought that these movements are caused by changes in seagrass availability. Their memory allows them to return to specific points after long travels. Dugong movements mostly occur within a localized area of seagrass beds, and animals in the same region show individualistic patterns of movement. Daily movement

826-459: A cow and calf have been reported in 2017, indicating a possible breeding had occurred in these waters. A single individual was recorded at Amami Ōshima , at the northernmost edge of the dugong's historic range, more than 40 years after the last previous recorded sighting. A vagrant strayed into a port near Ushibuka, Kumamoto, and died due to poor health. Historically, the Yaeyama Islands held

944-448: A depth of around 10 m (33 ft), although in areas where the continental shelf remains shallow dugongs have been known to travel more than ten kilometres (6 mi) from the shore, descending to as far as 37 metres (121 ft), where deepwater seagrasses such as Halophila spinulosa are found. Special habitats are used for different activities. It has been observed that shallow waters are used as sites for calving, minimizing

1062-532: A dugong can change due to the growth of algae on the skin. The body is sparsely covered in short hair, a common feature among sirenians which may allow for tactile interpretation of their environment. These hairs are most developed around the mouth, which has a large horseshoe-shaped upper lip forming a highly mobile muzzle. This muscular upper lip aids the dugong in foraging . The dugong's tail flukes and flippers are similar to those of dolphins . These flukes are raised up and down in long strokes to move

1180-492: A female first gives birth is disputed, ranging anywhere from 6 to 17 years. The time between births is unclear, with estimates ranging from 2 to 7 years. In Sarasota, Florida, 53 females under observation produced at least 55 calves during a five-year period. Manatees can reach sexual maturity as early as two to five years of age. Manatee gestation is around one year, and then they lactate for one to two years. West Indian manatees and African manatees can breed year-round, and

1298-464: A female will mate with multiple males. Amazonian manatees have a breeding season, usually mating when the river levels begin to rise, which varies from place to place. Manatees may be taken into captivity after being found stranded to facilitate their recovery, and there are many instances of manatees being successfully rehabilitated and released into the wild. As all extant sirenian species are rated as Vulnerable, these rehabilitation programs present

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1416-458: A few times during their lives and invest considerable parental care in their young. Dugongs generally gather in groups of less than a dozen individuals for one to two days. Since they congregate in turbid waters, little is known about their reproductive behavior. The males are often seen with scars, and the tusks on dugongs grow in first for males, suggesting they are important in lekking. They have also been known to lunge at each other. The age when

1534-406: A few times during their lives and invest considerable parental care in their young. The time between births is unclear, with estimates ranging from 2.4 to 7 years. Mating behaviour varies between populations located in different areas. In some populations, males will establish a territory that females in estrus will visit. In these areas, a male will try to impress the females while defending

1652-549: A large concentration of dugongs, with more than 300 individuals. On the Aragusuku Islands , large quantities of skulls are preserved at a utaki that outsiders are strictly forbidden to enter. Dugong populations in these areas were reduced by historical hunts as payments to the Ryukyu Kingdom , before being wiped out because of large-scale illegal hunting and fishing using destructive methods such as dynamite fishing after

1770-506: A large-scale interview survey conducted across four southern Chinese maritime provinces ( Hainan , Guangxi , Guangdong , and Fujian ) in the summer of 2019. In Vietnam, dugongs have been restricted mostly to the provinces of Kiên Giang and Bà Rịa–Vũng Tàu , including Phu Quoc Island and Con Dao Island , which hosted large populations in the past. Con Dao is now the only site in Vietnam where dugongs are regularly seen, protected within

1888-720: A maximum depth of 39 metres (128 ft); they spend most of their lives no deeper than 10 metres (33 ft). Communication between individuals is through chirps, whistles, barks, and other sounds that echo underwater. Different sounds have been observed with different amplitudes and frequencies, implying different purposes. Visual communication is limited due to poor eyesight and is mainly used for activities such as lekking for courtship purposes. Mothers and calves are in almost constant physical contact, and calves have been known to reach out and touch their mothers with their flippers for reassurance. Dugongs are semi-nomadic , often traveling long distances in search of food, but staying within

2006-557: A maximum of 300 grams (11 ounces), about 0.1% of the animal's body weight. The bodies of sirenians are sparsely covered in short hair ( vibrissae ), except that it becomes denser on the muzzle, which may allow for tactile interpretation of their environment. Manatees are the only known organism with uniformly vascularized corneas. This may be the result of irritation from or protection against their hypotonic freshwater environment. Sirenians are referred to as "sea cows" because their diet consists mainly of seagrass . Dugongs sift through

2124-521: A preferred diet for the dugongs. To ensure the abundance of favored seagrasses, dugongs exhibit sustained grazing pressure on seagrass patches up to a month or more. The grazing maximizes the presence of species preferred by the dugongs at the expense of less nutritious and less favored species. This grazing method also encourages rapid recovery of seagrass meadows- the dugongs graze in meandering, single trails that leave uncropped patches of seagrass. This ungrazed reserve with their surviving rhizomes are key to

2242-421: A protein source, oils, and a stabilizing agent. This concoction is supplemented with vitamins. During intake, young manatees might require electrolytes via intravenous hydration or even tube feeding if they continuously reject the bottle. After six months, they will be introduced to solid foods like romaine and iceberg lettuce, pumpkin, and root vegetables. After a year and a half, the weaning process will begin and

2360-769: A small population, with more scattered throughout the Malay Archipelago . All the islands of the Philippines once provided habitats for sizeable herds of dugongs. They were common until the 1970s when their numbers declined sharply due to accidental drownings in fishing gear and habitat destruction of seagrass meadows. Today, only isolated populations survive, most notably in the waters of the Calamian Islands in Palawan , Isabela in Luzon , Guimaras , and Mindanao . The dugong became

2478-421: A useful means to support these species. However, the vulnerability of these animals also means that the taking of manatees from the wild for commercial purposes is a conservation issue. Manatees tend to do well in a captive environment and have been known to thrive. However, it can be difficult to replicate the conditions of their natural environment to the extent necessary to maintain a manatee at its healthiest;

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2596-427: Is 2.0.3.3 3.1.3.3 , meaning they have two incisors, three premolars , and three molars on each side of their upper jaw, and three incisors, one canine, three premolars, and three molars on each side of their lower jaw. 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

2714-445: Is a marine mammal . It is one of four living species of the order Sirenia , which also includes three species of manatees . It is the 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 18th century. The dugong is the only sirenian in its range, which spans the waters of some 40 countries and territories throughout

2832-454: Is affected by the tides. In areas where there is a large tidal range, dugongs travel with the tide to access shallower feeding areas. In Moreton Bay, dugongs often travel between foraging grounds inside the bay and warmer oceanic waters. At higher latitudes dugongs make seasonal travels to reach warmer water during the winter. Occasionally individual dugongs make long-distance travels over many days and can travel over deep ocean waters. One animal

2950-455: Is by the eruption of tusks in the male since tusks erupt in males when testosterone levels reach a high enough level. The age when a female first gives birth is disputed, with some studies placing the age between ten and seventeen years, while others place it as early as six years. There is evidence that male dugongs lose fertility at older ages. Despite the longevity of the dugong, which may live for 50 years or more, females give birth only

3068-463: Is considered a luxury food and is also believed to have aphrodisiac properties. They are actively hunted in these regions, in some places to near-extinction. In Palau , dugongs were traditionally hunted with heavy spears from canoes. Although it is illegal and there is widespread disapproval of killing dugongs, poaching remains a major problem. Dugongs are also widely hunted in Papua New Guinea ,

3186-584: Is found in waters above 18 °C, and its range spans Senegal to Angola. The dugong ( Dugong dugong ), the closest living relative of Steller's sea cow, lives in the Indo-West Pacific Ocean in more than 40 different countries. They are coastal animals supported by wide protected sea grass meadows. Steller's sea cow was discovered in 1741 around islands in the Bering Sea and was specialized for cold subarctic temperatures. It ranged from Alaska through

3304-414: Is often caused by direct hunting by humans or other human-induced causes, such as habitat destruction , entanglement in fishing gear , and watercraft collisions . Steller's sea cow was driven to extinction due to overhunting in 1768. Sirenia, commonly sirenians , are also referred to by the common name sirens , deriving from the sirens of Greek mythology . Sirenians are classified within

3422-615: Is restricted to six provinces along the Andaman Sea , and very few dugongs are present in the Gulf of Thailand . The Gulf of Thailand was historically home to a large number of animals, but none have been sighted in the west of the gulf in recent years, and the remaining population in the east is thought to be very small and possibly declining. Dugongs are believed to exist in the Straits of Johor in very small numbers. The waters around Borneo support

3540-454: The Amchitka and Aleutian Islands , and even to Japan. Steller's sea cow was reported to have congregated in shallow, sandy areas along coastline and mouths of rivers and creeks to feed on kelp. The evolution of sirenians is characterized by the appearance of several traits that are found in all sirenians. The nostrils are large and retracted , the upper-jaw bone contacts the frontal bone ,

3658-463: The Côn Đảo National Park . Nonetheless, dangerously low levels of attention to the conservation of marine organisms in Vietnam and Cambodia may result in increased intentional or unintentional catches, and illegal trade is a potential danger for local dugongs. On Phu Quoc, the first 'Dugong Festival' was held in 2014, aiming to raise awareness of these issues. In Thailand, the present distribution of dugongs

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3776-522: The Indo-West Pacific . The dugong is largely dependent on seagrass communities for subsistence and is thus restricted to the coastal habitats that support seagrass meadows , with the largest dugong concentrations typically occurring in wide, shallow, protected areas such as bays , mangrove channels , the waters of large inshore islands and inter-reefal waters. The northern waters of Australia between Shark Bay and Moreton Bay are believed to be

3894-633: The Mafia Island Marine Park where a hunt was intended by fishermen but failed in 2009. In the Seychelles , dugongs had been regarded as extinct in the 18th century until a small number was discovered around the Aldabra Atoll . This population may belong to a different group than that distributed among the inner isles. Dugongs once thrived among the Chagos Archipelago and Sea Cow Island

4012-752: The Miocene . The Steller's sea cow became extinct in the 18th century. No fossils exist of other members of the Dugongidae. Molecular studies have been made on dugong populations using mitochondrial DNA . The results have suggested that the population of Southeast Asia is distinct from the others. Australia has two distinct maternal lineages, one of which also contains the dugongs from Africa and Arabia. Limited genetic mixing has taken place between those in Southeast Asia and those in Australia, mostly around Timor . One of

4130-519: The New World . In Western Europe the first and oldest sirenian remains have been found in a new paleontological site , in Santa Brígida, Amer (La Selva, Catalonia , Spain ). One of the earliest aquatic sirenians discovered is Prorastomus , which dates back to 40 million years ago, and the first known sirenian, the quadruped Pezosiren , lived 50 million years ago. An ancient sirenian fossil of

4248-611: The Oligocene and Miocene but subsequently declined as a result of climatic cooling, oceanographic changes, and human interference. The word "dugong" derives from the Visayan (probably Cebuano ) dugung . The name was first adopted and popularized by the French naturalist Georges-Louis Leclerc, Comte de Buffon , as " dugon " in Histoire Naturelle (1765), after descriptions of

4366-706: The Solomon Islands and New Caledonia , stretching to an easternmost population in Vanuatu . A highly isolated population lives around the islands of Palau . A single dugong lives at Cocos (Keeling) Islands although the animal is thought to be a vagrant. Today, possibly the smallest and northernmost population of dugongs exists around the Ryukyu islands, and a population formerly existed off Taiwan. An endangered population of 50 or fewer dugongs, possibly as few as three individuals, survives around Okinawa . New sightings of

4484-791: The Solomon Islands , Vanuatu , and New Caledonia ; where their meat and ornaments made from bones and tusks are highly prized in feasts and traditional rituals. However, hunting dugongs is considered taboo in some areas of Vanuatu. Dugong meat and oil have traditionally been some of the most valuable foods of Australian Aboriginals and Torres Strait Islanders . Some Aboriginals regard dugongs as part of their Aboriginality. Sirenia The Sirenia ( / s aɪ ˈ r iː n i . ə / ), commonly referred to as sea cows or sirenians , are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct families : Dugongidae (the dugong and

4602-419: The anus . The lungs in a dugong are very long, extending almost as far as the kidneys , which are also highly elongated to cope with the saltwater environment. If the dugong is wounded, its blood will clot rapidly. The skull of a dugong is unique. The skull is enlarged with a sharply down-turned premaxilla , which is stronger in males. The spine has between 57 and 60 vertebrae . Unlike in manatees,

4720-573: The cohort Afrotheria in the clade Paenungulata , alongside Proboscidea (elephants), Hyracoidea (hyraxes), Embrithopoda , Desmostylia , and Afroinsectiphilia . This clade was first established by George Gaylord Simpson in 1945 on the basis of anatomical evidence, such as testicondy and similar fetal development . The Paenungulata, along with the Afrotheria, are one of the most well-supported mammalian clades in molecular phylogeny. Sirenia, Proboscidae, and Desmotylia are grouped together in

4838-484: The diaphragm , these extend the entire length of the vertebral column, helping the animals control their buoyancy and reducing tipping in the water. Extant sirenians grow to between 2.5 and 4 metres (8.2 and 13.1 ft) in length and can weigh up to 1,500 kilograms (3,300 lb). Steller's sea cow was the largest known sirenian to have lived, and could reach lengths of 9 metres (30 ft) and weight of 8 to 10 tonnes (8.8 to 11.0 short tons). A dugong's brain weighs

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4956-512: The equator . Their historic range is believed to correspond to that of seagrasses from the Potamogetonaceae and Hydrocharitaceae families. The full size of the former range is unknown, although it is believed that the current populations represent the historical limits of the range, which is highly fractured. Their distributions during warmer periods of Holocene might have been broader than today. Today populations of dugongs are found in

5074-560: The sagittal crest is missing, the mastoid fills the supratemporal fenestra (an opening on the top of the skull), there is a drop-like ectotympanic (a bony ring that holds the ear drum ), and the bones are pachyosteosclerotic (dense and bulky). Sirenians first appeared in the fossil record in the Early Eocene and diversified throughout the epoch . They inhabited rivers, estuaries, and nearshore marine waters. Sirenians, unlike other marine mammals such as cetaceans , lived in

5192-726: The Caribbean, South America, and Central America and frequent drowned cays, mangroves, lagoons, and sea grass beds. The Amazonian manatee ( T. inunguis ) has been documented in all parts of the Amazon River Basin in South America. River channels that connect allow easy travel to other waterways where food may be plentiful. The Amazonian manatee lives only in freshwater. The West African manatee ( T. senegalensis ) lives in murky isolated inland mangroves and coastal flats in West Africa. It

5310-746: The Kimberley , Western Australia . Dugong dugon is the only extant species of the family Dugongidae , and one of only four extant species of the Sirenia order, the others forming the manatee family. It was first classified by Müller in 1776 as Trichechus dugon , a member of the manatee genus previously defined by Linnaeus . It was later assigned as the type species of Dugong by Lacépède and further classified within its own family by Gray and subfamily by Simpson . Dugongs and other sirenians are not closely related to other marine mammals , being more related to elephants . Dugongs and elephants share

5428-587: The Philippines, and Vietnam. Further disappearances are likely. Dugongs are generally found in warm waters around the coast with large numbers concentrated in wide and shallow protected bays. The dugong is the only strictly marine herbivorous mammal, as all species of manatee utilise fresh water to some degree. Nonetheless, they can tolerate the brackish waters found in coastal wetlands, and large numbers are also found in wide and shallow mangrove channels and around leeward sides of large inshore islands, where seagrass beds are common. They are usually located at

5546-488: The Philippines, some parts of Sabah (Malaysia), and northern Sulawesi and the Lesser Sunda Islands (Indonesia). Dugongs are predominantly not traditionally hunted for food in these regions and they remained plentiful until around the 1970s. Conversely, dugong "tears" are considered aphrodisiacs in other parts of Indonesia , Singapore , Malaysia , Brunei , Thailand , Vietnam , and Cambodia . Dugong meat

5664-587: The Second World War. Populations around Taiwan appear to be almost extinct, although remnant individuals may visit areas with rich seagrass beds such as Dongsha Atoll . Some of the last reported sightings were made in Kenting National Park in the 1950s and 60s. There had been occasional records of vagrants at the Northern Mariana Islands before 1985. It is unknown how much mixing there

5782-502: The Trichechidae in the late Eocene or early Oligocene (30–35 mya). Sirenians grow to between 2.5 and 4 metres (8.2 and 13.1 feet) in length and 1,500 kilograms (3,300 pounds) in weight. The recently extinct Steller's sea cow was the largest known sirenian to have lived, reaching lengths of 10 metres (33 feet) and weights of 5 to 10 tonnes (5.5 to 11.0 short tons). Sirenians have a large, fusiform body which reduces drag through

5900-490: The U2 and L1 fields. Dugongs and trichechids differ in how they use the U1 and U2 bristle fields during feeding. Dugongs use a medial-to-lateral motion for U2 bristles, while trichechids use a prehensile, lateral-to-medial grasping motion. These divergent feeding behaviors allow dugongs to exploit benthic foraging, including rhizome consumption, more effectively than trichechids. Food handling

6018-492: The animal forward and can be twisted to turn. The forelimbs are paddle-like flippers which aid in turning and slowing. The dugong lacks nails on its flippers, which are only 15% of a dugong's body length. The tail has deep notches. A dugong's brain weighs a maximum of 300 g (11 oz), about 0.1% of the animal's body weight. With very small eyes, dugongs have limited vision, but acute hearing within narrow sound thresholds. Their ears, which lack pinnae , are located on

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6136-416: The animal forward, or twisted to turn. The forelimbs are paddle-like flippers which aid in turning and slowing. Unlike manatees, the dugong lacks nails on its flippers, which are only 15% of a dugong's body length. Manatees generally glide at speeds of 8 kilometres per hour (5 mph), but can reach speeds of 24 kilometres per hour (15 mph) in short bursts. The body is fusiform to reduce drag in

6254-582: The animal from the island of Leyte in the Philippines . The name ultimately derives from Proto-Malayo-Polynesian *duyuŋ. Despite common misconception , the term does not come from Malay duyung and it does not mean "lady of the sea" ( Mermaid ). Other common local names include "sea cow", "sea pig" and "sea camel". It is known as the balguja by the Wunambal people of the Mitchell Plateau area in

6372-521: The anthropologist A. Asbjørn Jøn has noted, they are often considered the inspiration for mermaids , and people around the world developed cultures around dugong hunting. In some areas, it remains an animal of great significance, and a growing ecotourism industry around dugongs has had an economic benefit in some countries. There is a 5,000-year-old wall painting of a dugong, apparently drawn by Neolithic peoples, in Tambun Cave , Ipoh , Malaysia. This

6490-414: The appearance of the Dugongidae at this time, sirenians had evolved the characteristics of the modern order, including an aquatic, streamlined body with flipper-like fore limbs and no hind limbs, and a powerful tail with horizontal caudal fins which uses an up-and-down motion to move them through the water. The last of the sirenian families to appear, Trichechidae , apparently arose from early dugongids in

6608-498: The area from other males, a practice known as lekking . In other areas many males will attempt to mate with the same female, sometimes inflicting injuries to the female or each other. During this, the female will have copulated with multiple males, who will have fought to mount her from below. This greatly increases the chances of conception. Females give birth after a 13- to 15-month gestation , usually to just one calf. Birth occurs in very shallow water, with occasions known where

6726-521: The area has not fully vegetated. Only certain seagrass meadows are suitable for dugong consumption, due to the dugong's highly specialized diet. There is evidence that dugongs actively alter seagrass species compositions at local levels. Dugongs may search out deeper seagrass. Feeding trails have been observed as deep as 33 metres (108 ft), and dugongs have been seen feeding as deep as 37 metres (121 ft). Dugongs are relatively slow-moving, swimming at around 10 km/h (3 m/s). When moving along

6844-410: The back of the jaw. Adults lack incisors, canines, and premolars, and instead have 8 to 10 cheek teeth . Manatees have an unlimited supply of teeth moving in from the back and shedding in the front; these are continuously formed by a dental capsule behind the tooth row. These teeth are constantly worn down by the abrasive vascular plants they forage, particularly aquatic grasses. Unlike those of manatees,

6962-764: The clade Tethytheria . On the basis of morphological similarities, Tethytheria, Perissodactyla , and Hyracoidea were previously thought to be grouped together as the Altungulata , but this has been invalidated by molecular data. Procaviidae [REDACTED] Trichechidae [REDACTED] Dugongidae [REDACTED] Elephantidae [REDACTED] Orycteropodidae [REDACTED] Macroscelididae [REDACTED] Chrysochloridae [REDACTED] Potamogalidae [REDACTED] Tenrecidae [REDACTED] † = Extinct Family Dugongidae : Family Trichechidae : †Family Protosirenidae : †Family Prorastomidae : Distribution The warm shallow waters of

7080-544: The coastal areas. As these materials may be mistaken as food by dugongs, these may lead to death due to plastic ingestion. Overpopulation and lack of education of all coastal fisherfolk in the Philippines regarding marine trash are harming the coastal environment not only in Palawan but also across the islands of the Philippines . The first documented sighting in Sarangani Bay occurred in July 2024. Populations also exist around

7198-457: The densest bones in the animal kingdom. These may act as ballast , countering the buoyancy of their blubber and helping them remain suspended slightly below the water's surface. Manatees do not possess blubber per se, but rather have thick skin and consequently are sensitive to temperature changes. They often migrate to warmer waters whenever the water temperature dips below 20 °C (68 °F). The lungs of sirenians are unlobed; along with

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7316-415: The densest in the animal kingdom , may act as a ballast to help keep sirenians suspended slightly below the water's surface. An adult's length rarely exceeds 3 metres (10 ft). An individual this long is expected to weigh around 420 kilograms (930 lb). Weight in adults is typically more than 250 kilograms (550 lb) and less than 900 kilograms (1,980 lb). The largest individual recorded

7434-536: 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. Despite being legally protected in many countries, the main causes of population decline remain anthropogenic and include fishing-related fatalities, habitat degradation, and hunting. With its long lifespan of 70 years or more and slow rate of reproduction,

7552-479: The dugong is especially vulnerable to extinction. Dugongs are part of the Sirenia order of placental mammals which comprises modern "sea cows" ( manatees as well as dugongs) and their extinct relatives. Sirenia are the only extant herbivorous marine mammals and the only group of herbivorous mammals to have become completely aquatic. Sirenians are thought to have a 50-million-year-old fossil record (early Eocene -recent). They attained modest diversity during

7670-464: The dugong's contemporary stronghold. Like all modern sirenians, the dugong has a fusiform body with no dorsal fin or hind limbs . The forelimbs or flippers are paddle-like. The dugong is easily distinguishable from the manatees by its fluked, dolphin-like tail; moreover, it possesses a unique skull and teeth. Its snout is sharply downturned, an adaptation for feeding in benthic seagrass communities. The molar teeth are simple and peg-like, unlike

7788-467: The dugong's teeth do not continually grow back via horizontal tooth replacement. The dugong has two incisors ( tusks ) which emerge in males during puberty. The female's tusks continue to grow without emerging during puberty, sometimes erupting later in life after reaching the base of the premaxilla . The number of growth layer groups in a tusk indicates the age of a dugong, and the cheek teeth move forward with age. The full dental formula of dugongs

7906-459: The dugong's teeth do not continually grow back via horizontal tooth replacement. The dugong has two tusks which emerge in males during puberty, and sometime later in life for females after reaching the base of the premaxilla . The number of growth layer groups in a tusk indicates the age of a dugong. Sirenians exhibit pachyostosis , a condition in which the ribs and other long bones are solid and contain little or no bone marrow . They have among

8024-588: The equator have been the center of Sirenian habitation. The northernmost living population, the Florida subspecies of the West Indian manatee ( T. manatus latirostris ), inhabits the coast and frequents freshwater springs, power plants, and canals in Florida to stay warm during the winter. Individuals may migrate north in the warm summer months, some up to 1,000 kilometers (about 621.37 mi) from their winter range. The Antillean subspecies ( T. manatus manatus ) occurs in

8142-606: The expansion and restoration of seagrasses. Seagrasses respond to cropping by increasing nitrogen levels and decreasing lignin. Cultivation grazing allows dugongs to increase both nutritionally superior seagrasses, but the overall nutritional quality of the seagrasses. By maintaining the seagrasses in an immature state, dugongs ensure the highest level of nutrition. Despite being mostly solitary, sirenians congregate in groups while females are in estrus . These groups usually include one female with multiple males. Sirenians are K -selectors ; despite their longevity, females give birth only

8260-454: The feeding ecology. Dugongs are constrained in their feeding by their rudimentary dentition and limited nitrogen abundance in seagrasses. To counter this, they use a strategy called "cultivation grazing". This grazing can alter the composition of seagrass communities and favor species. Early and rapidly growing species will succeed over slow-growing species. Oftentimes, these "pioneer" species can be high in nitrogen and low in fibre, making them

8378-414: The first marine animal protected by Philippine law, with harsh penalties for harming them. Recently, the local marine trash problem in the archipelago remained unabated and became the biggest threat to the already dwindling population of Dugongs in the country. Litters of plastic waste (single-use sachets, plastic bottles , fast food to-go containers, etc.) and other non-biodegradable materials abound in

8496-441: The inability of seagrass beds to support large populations. Gatherings of hundreds of dugongs sometimes happen, but they last only for a short time. Because they are shy and do not approach humans, little is known about dugong behavior. They can go six minutes without breathing (though about two and a half minutes is more typical), and have been known to rest on their tails to breathe with their heads above water. They can dive to

8614-540: The juvenile manatees will be offered less and less milk during feeding times, slowly transitioning to a completely solid food diet. The three extant manatee species (family Trichechidae) and the dugong (family Dugongidae) are rated as Vulnerable on the IUCN Red List of Threatened Species . All four are vulnerable to extinction from habitat loss and other negative impacts related to human population growth and coastal development. Steller's sea cow , extinct since 1768,

8732-651: The largest (about 120 individuals) occurs at Bazaruto Island , but they have become rare in historical habitats such as in Maputo Bay and on Inhaca Island . The Bazaruto Island population is possibly the last long-term viable population in East Africa, with only some of its core territory lying within protected waters. The East African population is genetically distinct from those of the Red Sea and those off Madagascar. In Tanzania , observations have recently increased around

8850-458: The late 1960s, herds of up to 500 dugongs were observed off the coast of East Africa and nearby islands. Current populations in this area are extremely small, numbering 50 and below, and it is thought likely they will become extinct. The eastern side of the Red Sea is home to large populations numbering in the hundreds, and similar populations are thought to exist on the western side. In the 1980s, it

8968-471: The late Eocene or early Oligocene. In 1994, the family was expanded to include not only the subfamily Trichechinae ( Potamosiren , Ribodon , and Trichechus ), but also Miosireninae ( Anomotherium and Miosiren ). The African manatee and the West Indian manatee are more closely related to each other than to the Amazonian manatee. Dugongidae comprises the subfamilies Dugonginae and Hydrodamalinae and

9086-527: The lineages stretches from Moreton Bay to Western Australia , while the other only stretches from Moreton Bay to the Northern Territory . There is not yet sufficient genetic data to make clear boundaries between distinct groups. The dugong's body is large with a cylindrical shape that tapers at both ends. It has thick, smooth skin that is a pale cream colour at birth, but darkens dorsally and laterally to brownish-to-dark-grey with age. The colour of

9204-519: The manatee to graze for several hours per day. By contrast, 10% of the diet of the African manatee is fish and mollusks . Manatees have been known to eat small amounts of fish from nets. As opposed to bulk feeding , dugongs target high-nitrogen grasses to maximize nutrient intake, and, although predominantly herbivorous , dugongs will occasionally eat invertebrates such as jellyfish , sea squirts , and shellfish . Some populations of dugongs, such as

9322-549: The manatee's diet is marine or estuarine plants. When compared to the captive diet, aquatic plants have more dry matter and soluble neutral detergent fiber, and less digestible nutrients. Although more easily digestible nutrients may seem to represent a better diet, a manatee's gastrointestinal tract is adapted to the wild diet through microbial processes of fermentation. Rescue and rehabilitation efforts often involve orphaned infant manatees. In captivity, young manatees will be bottle-fed an amino acid-based milk formula that includes

9440-399: The misconception that the word "dugong" itself means "lady of the sea". A common belief found in the Philippines, Malaysia , Indonesia , and Thailand , is that dugongs were originally human or part-human (usually women), and that they cry when they are butchered or beached . Because of this, it is considered bad luck if a dugong is killed or accidentally dies in nets or fish corrals in

9558-467: The more elaborate molar dentition of manatees. The dugong has been hunted for thousands of years for its meat and oil . Traditional hunting still has great cultural significance in several countries in its modern range, particularly northern Australia and the Pacific Islands. The dugong's current distribution is fragmented, and many populations are believed to be close to extinction. The IUCN lists

9676-562: The mothers were almost on the shore. As soon as the young is born the mother pushes it to the surface to take a breath. Newborns are already 1.2 metres (4 ft) long and weigh around 30 kilograms (65 lb). Once born, they stay close to their mothers, possibly to make swimming easier. The calf nurses for 14–18 months, although it begins to eat seagrasses soon after birth. A calf will only leave its mother once it has matured. Dugongs have historically provided easy targets for hunters, who killed them for their meat, oil, skin, and bones. As

9794-711: The nearest population in India. Former populations in this area, centered on the Maldives and the Lakshadweep , are presumed to be extinct. A population exists in the Gulf of Mannar Marine National Park and the Palk Strait between India and Sri Lanka , but it is seriously depleted. Recoveries of seagrass beds along former ranges of dugongs, such as the Chilika Lake have been confirmed in recent years, raising hopes for re-colorizations of

9912-491: The north of the Northern Territory , with a population of over 20,000 in the Gulf of Carpentaria alone. A population of over 25,000 exists in the Torres Strait such as off Thursday Island , although there is significant migration between the strait and the waters of New Guinea . The Great Barrier Reef provides important feeding areas for the species; this reef area houses a stable population of around 10,000, although

10030-468: The now extinct Steller's sea cow ) and Trichechidae ( manatees , namely the Amazonian manatee, West Indian manatee, and West African manatee) with a total of four species. The Protosirenidae (Eocene sirenians) and Prorastomidae (terrestrial sirenians) families are extinct. Sirenians are classified in the clade Paenungulata , alongside the elephants and the hyraxes , and evolved in the Eocene 50 million years ago (mya). The Dugongidae diverged from

10148-476: The oil of the African manatee can cure ailments such as ear infections, rheumatism , and skin conditions. Hunting is the largest source of mortality in Amazonian manatees, and there are no management plans except in Colombia. Amazonian manatees, especially calves, are sometimes illegally sold as pets, but there are several institutions that care for and rescue these orphans, with the possibility of releasing them into

10266-703: The oldest recorded specimen reached age 73. They have few natural predators, although animals such as crocodiles, killer whales, and sharks pose a threat to the young, and a dugong has also been recorded to have died from trauma after being impaled by a stingray barb. A large number of infections and parasitic diseases affect dugongs. Detected pathogens include helminths , cryptosporidium , different types of bacterial infections, and other unidentified parasites. 30% of dugong deaths in Queensland since 1996 are thought to be because of disease. Although they are social animals , they are usually solitary or found in pairs due to

10384-634: The one in Moreton Bay , Australia, are omnivorous, feeding on invertebrates such as polychaetes or marine algae when their supply of seagrasses is low. In other dugong populations in western and eastern Australia, there is evidence that dugongs actively seek out large invertebrates. Populations of Amazonian manatees become restricted to lakes during the July–August dry season when water levels begin to fall, and are thought to fast during this period. Their large fat reserves and low metabolic rates—only 36% of

10502-455: The paraphyletic Halitheriinae. The tusks of modern-day dugongs may have originally been used for digging, but they are now used for social interaction. The genus Dugong probably originated in the Indo-Pacific. The tail fluke of a dugong is notched and similar to those of dolphins , whereas the tail fluke of manatee is paddle-shaped. The fluke is pumped up and down in long strokes to move

10620-483: The population concentration has shifted over time. Large bays facing north on the Queensland coast provide significant habitats for dugong, with the southernmost of these being Hervey Bay and Moreton Bay. Dugongs had been occasional visitors along the Gold Coast where a re-establishment of a local population through range expansions has started recently. The Persian Gulf has the second-largest dugong population in

10738-517: The rapidly growing, higher nutrient seagrasses that dugongs prefer. Dugongs may also prefer to feed on younger, less fibrous strands of seagrasses, and cycles of cultivation feeding at different seagrass meadows may provide them with a greater number of younger plants. Due to their poor eyesight, dugongs often use smell to locate edible plants. They also have a strong tactile sense and feel their surroundings with their long sensitive bristles. They will dig up an entire plant and then shake it to remove

10856-549: The risk of predation. Deep waters may provide a thermal refuge from cooler waters closer to the shore during winter. Australia is home to the largest population, stretching from Shark Bay in Western Australia to Moreton Bay in Queensland . The population of Shark Bay is thought to be stable with over 10,000 dugongs. Smaller populations exist up the coast, including one in Ashmore Reef . Large numbers of dugongs live to

10974-400: The sand before eating it. They have been known to collect a pile of plants in one area before eating them. The flexible and muscular upper lip is used to dig out the plants. This leaves furrows in the sand in their path. A dugong reaches sexual maturity between the ages of eight and eighteen, older than in most other mammals. The way that females know how a male has reached sexual maturity

11092-430: The seabed to feed they walk on their pectoral fins. Dugong feeding may favor the subsequent growth of low-fibre, high-nitrogen seagrasses such as Halophilia and Halodule. Species such as Zosteria capricorni are more dominant in established seagrass beds, but grow slowly, while Halophilia and Halodule grow quickly in the open space left by dugong feeding. This behavior is known as cultivation grazing and favors

11210-552: The seafloor in search of seagrasses, using their sense of smell because their eyesight is poor. They ingest the whole plant, including the roots, although they will feed on just the leaves if this is not possible. Using its divided upper lip, the West Indian manatee is known to consume over 60 different freshwater and saltwater plants, such as shoalweed , water lettuce , muskgrass , manatee grass , and turtle grass . An adult manatee will commonly eat up to 10–15% of its body weight, or 50 kilograms (110 lb), per day, which requires

11328-409: The sides of their head. The nostrils are located on top of the head and can be closed using valves. Dugongs have two teats , one located behind each flipper. There are few differences between the sexes; the body structures are almost the same. A male's testes are not externally located, and the main difference between males and females is the location of the genital aperture to the umbilicus and

11446-416: The species of plants consumed, as reflected in the mean feeding cycle length. Thus, Florida manatees adapt their feeding behavior depending on the characteristics of the plants they consume. They exhibit different food handling strategies and efficiencies based on the plant species, with faster consumption observed for plants with tubular stems and numerous branches. This research provides valuable insights into

11564-699: The species. The population around the Andaman and Nicobar Islands is known only from a few records, and although the population was large during British rule, it is now believed to be small and scattered. A small population existed along the southern coast of China , particularly the Gulf of Tonkin (Beibu Gulf), where efforts were made to protect it, including the establishment of a seagrass sanctuary for dugong and other endangered marine fauna ranging in Guangxi . Despite these efforts, numbers continued to decrease, and in 2007 it

11682-464: The supply of their choice grasses decreases. In other southern areas of both western and eastern Australia, there is evidence that dugongs actively seek out large invertebrates. This does not apply to dugongs in tropical areas, in which fecal evidence indicates that invertebrates are not eaten. Most dugongs do not feed on lush areas, but where the seagrass is more sparse. Additional factors such as protein concentration and regenerative ability also affect

11800-430: The surface, sometimes standing on their tails to do so. They typically inhabit warm, shallow, coastal waters, or rivers. They are mainly herbivorous, but have been known to consume animals such as birds and jellyfish. Males typically mate with more than one female and may gather in leks to mate. Sirenians are K -selected , displaying parental care . The meat, oil, bones, and skins are commercially valuable. Mortality

11918-551: The typical diet fed to captive manatee populations may contain insufficient quantities of the nutrients they need. Manatee captive-fed diets vary greatly from the manatee's diet in the wild. In captivity manatees are fed 70–80% leafy green vegetables, 10–20% dried forage, and 5% vegetables and fruits. Dried forage is foods such as hay and timothy grass, which are often used as horse and cattle feed. The vegetables and fruits that are fed to manatees include romaine lettuce, carrots, and apples. In their natural habitat approximately half of

12036-678: The usual placental mammal metabolic rate—allow them to survive for up to seven months with little or no food. Perioral bristles are not only used to sense things, but can be used to grasp and manipulate food. Of the 6 distinct fields of bristles on upper and lower lips, the perioral fields have distinct length-to-diameter ratios, defining their boundaries. Macrovibrissae are used to detect food by its size and microvibrissae to manipulate food. They can be used to break off leaves and undesirable parts while feeding. Sirenians use their elaborate facial musculature along with perioral bristles to acquire, manipulate, and ingest aquatic vegetation. The snout makes up

12154-479: The value of a seagrass bed. The chemical structure and composition of the seagrass are important, and the grass species most often eaten are low in fiber, high in nitrogen, and easily digestible. In the Great Barrier Reef, dugongs feed on low-fiber high-nitrogen seagrass such as Halophila and Halodule , to maximize nutrient intake instead of bulk eating. Seagrasses of a lower seral are preferred, where

12272-580: The water and heavy bones that act as ballast to counteract the buoyancy of their blubber . They have a thin layer of blubber and consequently are sensitive to temperature fluctuations, which cause migrations when water temperatures dip too low. Sirenians are slow-moving, typically coasting at 8 kilometres per hour (5.0 miles per hour), but they can reach 24 kilometres per hour (15 miles per hour) in short bursts. They use their strong lips to pull out seagrasses , consuming 10–15% of their body weight per day. While breathing, sirenians hold just their nostrils above

12390-542: The water of the Mediterranean possibly until after the rise of civilizations along the inland sea . This population possibly shared ancestry with the Red Sea population, and the Mediterranean population had never been large due to geographical factors and climate changes . The Mediterranean is the region where the Dugongidae originated in the mid-late Eocene , along with Caribbean Sea . Dugongs are long-lived, and

12508-454: The water. Like those of cetaceans, the hind limbs are internal and vestigial . The snout is angled downwards to aid in bottom-feeding . Sirenians typically make two- to three-minute dives, but manatees can hold their breath for up to 15 minutes while resting and dugongs up to six minutes. They may stand on their tails to hold their heads above water. Much like elephants, manatees are polyphyodonts , continuously replacing their teeth from

12626-407: The waters of 37 countries and territories. Recorded numbers of dugongs are generally believed to be lower than actual numbers, due to a lack of accurate surveys. Despite this, the dugong population is thought to be shrinking, with a worldwide decline of 20 percent in the last 90 years. They have disappeared from the waters of Hong Kong , Mauritius , and Taiwan, as well as parts of Cambodia , Japan,

12744-559: The whole plant, including the roots, although when this is impossible they will feed on just the leaves. A wide variety of seagrass has been found in dugong stomach contents, and evidence exists they will eat algae when seagrass is scarce. Although almost completely herbivorous , they will occasionally eat invertebrates such as jellyfish , sea squirts , and shellfish . Dugongs in Moreton Bay, Australia, are omnivorous, feeding on invertebrates such as polychaetes or marine algae when

12862-522: The world, inhabiting most of the southern coast, and the current population is believed to range from 5,800 to 7,300. In the course of a study carried out in 1986 and 1999 on the Persian Gulf, the largest reported group sighting was made of more than 600 individuals to the west of Qatar . A 2017 study found a nearly 25% drop in population since 1950. Reasons for this drastic population loss include illegal poaching, oil spills , and net entanglement. In

12980-461: Was 4.06 metres (13 ft 4 in) long and weighed 1,016 kilograms (2,240 lb), and was found off the Saurashtra coast of west India . Females tend to be larger than males. Dugongs are found in warm coastal waters from the western Pacific Ocean to the eastern coast of Africa, along an estimated 140,000 kilometres (87,000 mi) of coastline between 26° and 27° to the north and south of

13098-470: Was between these populations historically. Some theorize that populations existed independently, for example, that the Okinawan population was isolated members derived from the migration of a Philippine subspecies. Others postulate that the populations formed part of a super-population where migration between Ryukyu , Taiwan , and the Philippines was common. It has been confirmed that dugongs once inhabited

13216-508: Was discovered by Lieutenant R.L. Rawlings in 1959 while on a routine patrol. Dugongs feature in Southeast Asian, especially Austronesian , folklore . In languages like Ilocano , Mapun , Yakan , Tausug , and Kadazan Dusun of the Philippines and Sabah , the name for dugongs is a synonym for "mermaid". In Malay , they are sometimes referred to as perempoen laut ("woman of the sea") or putri duyong ("dugong princess"), leading to

13334-453: Was estimated there could be as many as 4,000 dugongs in the Red Sea. Dugong populations in Madagascar are poorly studied, but due to widespread exploitation, it is thought they may have severely declined, with few surviving individuals. The resident population around Mayotte is thought to number just 10 individuals. In Mozambique , most of the remaining local populations are very small and

13452-431: Was hunted to extinction by humans. The meat, oil, bones, and skin of manatees have commercial value. In some countries, such as Nigeria and Cameroon, African manatees are sold to zoos, aquariums, and online as pets, sometimes being shipped internationally. Though hunting of them is illegal, lack of law enforcement in these areas allows poaching . Some residents of West African countries, such as Mali and Chad, believe that

13570-561: Was measured by observing the length of cyclic movements (feeding cycles) of the manatees' perioral bristles used to introduce food into their mouths. Mean feeding cycle lengths varied based on the manatees' body size and the species of plant being consumed. Rates of food introduction, derived from mean feeding cycle lengths, were comparable to chewing rates reported in other studies. Manatees consumed plants with tubular stems and numerous branches more quickly than plants with flat blades. Food handling time using perioral bristles differed depending on

13688-486: Was named after the species, although the species no longer occurs in the region. There are less than 250 individuals scattered throughout Indian waters. A highly isolated breeding population exists in the Marine National Park, Gulf of Kutch , the only remaining population in western India. It is 1,500 kilometres (800 nautical miles) from the population in the Persian Gulf, and 1,700 kilometres (900 nmi) from

13806-628: Was reported that no more dugong could be found on the west coast of the island of Hainan . Historically, dugongs were also present in the southern parts of the Yellow Sea . The last confirmed record of dugongs in Chinese waters was documented in 2008. In August 2022, an article published on the Royal Society Open Science concluded that dugongs were functionally extinct in China, which was based on

13924-415: Was seen as far south as Sydney . Although they are marine creatures, dugongs have been known to travel up creeks, and in one case a dugong was caught fifteen kilometres (8 nmi) up a creek near Cooktown . Dugongs, along with other sirenians , are referred to as "sea cows" because their diet consists mainly of seagrass , particularly the genera Halophila and Halodule . When eating they ingest

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