Manatee – Part 1

Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West African manatee (Trichechus senegalensis). They measure up to 4.0 metres (13.1 ft) long, weigh as much as 590 kilograms (1,300 lb), and have paddle-like flippers.  Manatees are occasionally called sea cows, as they are slow plant-eaters, peaceful and similar to cows on land. They often graze on water plants in tropical seas.

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Manatees are three of the four living species in the order Sirenia. The fourth is the Eastern Hemisphere’s dugong. The Sirenia are thought to have evolved from four-legged land mammals more than 60 million years ago, with the closest living relatives being the Proboscidea (elephants) and Hyracoidea (hyraxes).[

The Amazonian’s hair color is brownish gray, and it has thick wrinkled skin, often with coarse hair, or “whiskers”. Photos are rare; although very little is known about this species, scientists think it is similar to West Indian manatee.

Description

Manatees weigh 400 to 550 kilograms (880 to 1,210 lb), and average 2.8 to 3.0 metres (9.2 to 9.8 ft) in length, sometimes growing to 4.6 metres (15 ft) and 1,775 kilograms (3,913 lb) (the females tend to be larger and heavier). At birth, baby manatees weigh about 30 kilograms (66 lb) each. The manatee has a large, flexible, prehensile upper lip, used to gather food and eat and for social interaction and communication. Manatees have shorter snouts than their fellow sirenians, the dugongs. The lids of manatees’ small, widely spaced eyes close in a circular manner. The adults have no incisor or canine teeth, just a set of cheek teeth, which are not clearly differentiated into molars and premolars. These teeth are repeatedly replaced throughout life, with new teeth growing at the rear as older teeth fall out from farther forward in the mouth, somewhat as elephants’ teeth do. At any time, a manatee typically has no more than six teeth in each jaw of its mouth. Its 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 female manatee has two teats, one under each flipper, a characteristic that was used to make early links between the manatee and elephants.

The manatee is unusual among mammals in having just six cervical vertebrae, a number that may be due to mutations in the homeotic genes. All other mammals have seven cervical vertebrae, other than the two-toed and three-toed sloths.

Like the horse, the manatee has a simple stomach, but a large cecum, in which it can digest tough plant matter. Generally, the intestines are about 45 meters, unusually long for an animal of the manatee’s size.

skeleton of a manatee and calf, on display at The Museum of Osteology, Oklahoma City, Oklahoma

More about these gentle giants in Part 2 of Manatees.

(Information from Wikipedia, the free encyclopedia)