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Sirenian bones are exceptionally dense, most of them lacking marrow. This adaptation is thought to help maintain neutral buoyancy. Manatees and dugongs differ in a number of traits besides the shape of the tail. Manatees lack incisor teeth, but incisors do occur in dugongs, erupting as tusks in the males.
The Sirenia (/ saɪˈriːni.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 the now extinct Steller's sea cow) and Trichechidae ...
Sirenians have two flippers; manatees have three to four nails on the second, third and fourth digits, while dugongs lack nails. All sirenians lack hind limbs, and have gray-brown skin that is smooth in some species, such as Amazonian manatees, or wrinkled in others, such as West Indian manatees. Adults are between 2.8 and 3.5 meters long.
The modern manatees evolved from early dugongids in freshwater regions of northern South America in the Miocene. Expansion to Africa and North America occurred in the Pliocene or Pleistocene. The living and recent members of the order Sirenia are divided into two families, Trichechidae and Dugongidae. The Trichechidae contains three species in ...
Jan 4, 2021 · Sirenians have a strong preference for warm waters. However, there is a difference between dugong and manatee habitats. Dugongs are exclusively marine, while manatees inhabit both marine and freshwater systems. They live in swamps, rivers, estuaries, marine wetlands, and coastal marine water. Sirenians have no dorsal fin.
Manatees and dugongs. 8. Manatees and dugongs. In ancient Greek mythology Proteus was the herdsman of Poseidon’s seals, a god who could change himself into any sort of creature – leopard, tree, snake, water, anything. Today we imagine that Nature, although slower, has a similar capacity: leopards, snakes, rhododendrons, mushrooms, sharks ...
Sirenia is the order of placental mammals which comprises modern "sea cows" (manatees and the Dugong) and their extinct relatives. They 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 ...
