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The dugong (/ ˈ d (j) uː ɡ ɒ ŋ /; Dugong dugon) 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.
Dugong skeleton displayed at Philippine National Museum. Dugongidae's body weight ranges from 217 to 307 kg for juveniles, 334 to 424 kg for subadults, and 435 to 568.5 kg for adults. Oral temperatures for individual dugongs is determined from 24° to 34.2 °C. Heart rate readings are from 40 to 96 bpm and vary between individual dugongs.
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.
Paenungulata (from Latin paene "almost" + ungulātus "having hoofs") is a clade of "sub-ungulates", which groups three extant mammal orders: Proboscidea (including elephants), Sirenia (sea cows, including dugongs and manatees), and Hyracoidea . At least two more possible orders are known only as fossils, namely Embrithopoda and Desmostylia. [a]
Amazonian manatee Dugong West Indian manatee. Sirenians, along with Proboscidea (elephants), group together with the extinct Desmostylia and likely the extinct Embrithopoda to form the Tethytheria. Tethytheria is thought to have evolved from primitive hoofed mammals ("condylarths") along the shores of the ancient Tethys Ocean.
A fossil reveals how a now-extinct species of dugong was swimming in the sea about 15 million years ago when it was preyed upon by a crocodile and a tiger shark.
A humpback whale (Megaptera novaeangliae) A leopard seal (Hydrurga leptonyx). Marine mammals are mammals that rely on marine (saltwater) ecosystems for their existence. They include animals such as cetaceans (whales, dolphins and porpoises), pinnipeds (seals, sea lions and walruses), sirenians (manatees and dugongs), sea otters and polar bears.
The manatee's tail is paddle-shaped, and is the clearest visible difference between manatees and dugongs; a dugong tail is fluked, similar in shape to that of a whale. The manatee is unusual among mammals in having just six cervical vertebrae, [11] a number that may be due to mutations in the homeotic genes. [12]