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Related to sirenian: pinniped, cetacean


(sīrē`nēən) or

sea cow,

name for a large aquatic mammal of the order Sirenia. Living sirenians are the dugong and the manatee, both found in warm, shallow waters in sheltered regions, where they feed on seaweeds and seagrasses. Sirenians are the only marine mammals, outside of the whalewhale,
aquatic mammal of the order Cetacea, found in all oceans of the world. Members of this order vary greatly in size and include the largest animals that have ever lived. Cetaceans never leave the water, even to give birth.
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 order, that spend their entire lives in the water, and they are the only marine mammals that feed exclusively on vegetation. Their heavy, thickset bodies are fishlike in form, the tail ending in a horizontally flattened fin. There are no hind legs, and the forelegs are modified into weak flippers. The gray skin is largely hairless, but there are short bristles (vibrissae) concentrated around the fleshy lips and distributed more sparsely on the body that aid the sense of touch; the upper lip is cleft into two lobes, used for gathering food. The female has a pair of mammary glands on the chest, and holds the pup in her flippers while nursing. It has been speculated that the manatees, which nurse on the water's surface, are the source of mermaidmermaid,
in folklore, sea-dwelling creature commonly represented as having the head and body of a woman and a fishtail instead of legs. Belief in mermaids, and in their counterpart, mermen, has existed since earliest times.
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Manatees (genus Trichechus) are found on both sides of the tropical Atlantic Ocean. They are sluggish, largely nocturnal bottom feeders and consume up to 100 lb (45 kg) of vegetation daily. They must surface for air every 15 or 20 min. They are usually 7 to 12 ft (2.1–3.6 m) long and weigh about 500 lb (225 kg), although males sometimes grow much larger. Their paddlelike tail fin is nearly circular. Both parents care for the young, one holding it while the other dives for food. The West Indian manatee, Trichechus manatus, lives in offshore waters, bays, estuaries, and river mouths in Florida, Central America, and the West Indies. It is protected by law in Florida. The Amazonian manatee, T. inunguis, is found in rivers of NE South America, ascending the Amazon as far as Ecuador. Both are listed as endangered species. The West African manatee, T. senegalensis, lives in the coastal rivers and lagoons of W Africa.


The dugong, Dugong dugon, is found in offshore waters of the Red Sea, Indian Ocean, and W South Pacific Ocean. More strictly marine than the manatee, it seldom enters rivers. Its tail fin is crescent-shaped, and the male has long, tusklike incisor teeth. The male may reach a length of 12 ft (3.6 m) and weigh over 600 lb (270 kg). The dugongs' numbers have been depleted by hunting for its flesh, hides, tusks, and oil. The extinct Steller's sea cow was a large northern species that formerly inhabited the Bering Straits. It reached a length of 30 ft (9 m), weighed up to 4 tons (2,400 kg), and was insulated by very thick blubber. When it was discovered by Bering in 1741, the population was very small; within 30 years it was exterminated by hunting.

Evolution and Classification

Although superficially they resemble whales, sirenians have evolved independently. They are descended from the group of ancient land mammals that also gave rise to the elephants. The living sirenians are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Mammalia, order Sirenia, families Trichechidae and Dugongidae.

References in periodicals archive ?
This body of water is known to contain at least 31 species of marine mammals, including 28 cetaceans, two species of pinnipeds and one species of sirenian (Schmidly & Melcher 1974a; 1974b; Schmidly 1981; Jefferson et al.
In 1990 she founded and become musical director of the internationally acclaimed Cantorian Sirenian Singers, an adult mixed voice choir which was the first Welsh choir to win the prestigious Choir of the World Competition at Llangollen International Eisteddfod, together with numerous accolades throughout Europe and the UK.
The choir features The Sirenian Singers, Cr Caerdydd, The South African Fezeka Choir and the newly-formed Llangollen International Eisteddfod Chorus.
The show comes to Mold's Clwyd Theatr Cymru this month, combining energetic dance with the Sirenian Singers, Rambert's associate orchestra and soloists Elin Manahan Thomas and Adrian Powter Speaking to the Daily Post he explains how his career has come full circle.
For those who enjoy a musical treat during the festive season, why not pop along to a Christmas Concert by the Sirenian Singers under their music director Jean Stanley-Jones?
She went on to become a founder member of Flintshire Youth Choir, and later joined the Four Counties Youth Choir, National Youth Choir and award-winning Sirenian Singers.
AWARD-winning Sirenian Singers will be celebrating their 30th anniversary at theWilliam Aston Hall, Wrexham at 7.
THE Alyn Lightfoot memorial concert given by the Sirenian Singers at Bethesda Chapel, Mold on Saturday, October 18 raised pounds 2,158.
Founder and musical director Gareth Jones will be conducting the concert and will be joined by four Welsh choirs, COr Caerdydd, Risca Male Choir, Serendipity and the Sirenian Singers, as well as world-class soloists soprano Claire Rutter, mezzo soprano Leah-Marian Jones, tenor Gregory Turay and bass baritone Terfel for the anniversary performance.
THE Sirenian Singers will give a charity memorial concert at Bethesda Chapel, Mold, in honour of one of the mixed choir's founder members Alyn Lightfoot, who died earlier this year.
Three of the best mixed voice choirs in North Wales, Cor Rhuthun, the Sirenian Singers from the Wrexham area and Cor Eifionydd, have come together for this production, together with the orchestra, Sinfonia Cymru, under the baton of Gareth Jones.
The Sirenian Singers give the pre-Christmas concert and will be performing music from six centuries including what they intriguingly call "unusual Christmas pieces" in their programme.