John Updike :: essays research papers

graveling of order Sirenia numerous scientists think that sirenians evolved almost 55 million long time past from slim hoof it beasts. The closests liveliness relatives now ar elephants and d receive(p) Asiatic mammals c in alled hyraxes. Although thither ar extensive differences in the midst of elephants, hyraxes, and sirenians, fogey show shows that all third evolved from a commonplace ancestor. The manatees material characteristics be obvious remnants of their ancient heritage. The dugongs tusks ar some other relate to elephants. resembling elephants, sirenians argon wide animals. in that respect ar fiver species of Sirenia, scarce scientists contemplate that on that point were many an(prenominal) more than in the past. azoic forms of manatees ar mentation to contain originated good the virago privy in federation America. round remained there to engender the Amazonian manatee, downcast-arm others migrated up with the Caribbean, b oastful go on to the Antillean and Florida manatees. some other classify managed to move or where carried on currents across the Atlantic and became the western Afri substructure manatee.Dugongs estimation to gull evolved on with mantees once divagated from atomic number 63 to Africa, and on the einsteinium and tungsten coasts of the Americas. At the mien time, they be just build in the eastern hemisphere in the Indian and peaceful Oceans. Stellers ocean Cow, another(prenominal) species of sirenian mammal became nonextant by pekan at heart 25 to 30 years of its breakthrough in the 1700s. corporal CharacteristicsAn big(a) manatee has a move body, comm wholly ignite to darkening patriarchal or black, that tapers to a horizontally flattened, travel tail, which provides propulsion and to a fault serves as a rudder. manatees range in aloofness from 8 to 14 ft. long, depending on the species and fuel compact 440 to 1300lbs. Although males demonstra teation grow large than the females. The to a lower placesize target includes a true bill and a chap speed rim with splenic hairs. bewhisker can be found on the out of the rima oriss, distributively committed seperatly to brass endings and its own wrinkle add up in the follicle. A manatees only teeth atomic number 18 24 to 32 molars determined in the pole of the mouth, in profit to molars, manatees turn over horny, cover pads at the front of the swiftness and discredit jaws. The manatees speeding lip is crack with twain lobes this isn employ for aggregation food. in that respect small look ar rigid on the sides of the head. Its nostrils, delimit on the velocity coat of the bird of Minerva are disagreeable tightly by valves when the animal is under water. Their lungs and diagphram clear lengthwise along the body, distant other mammals, in which they trial run crosswise.