Editing Manatee (section)

==Description==
[[File:Manatee skeleton with calf.jpg|thumb|left|A skeleton of a manatee and calf, the [[Museum of Osteology]], [[Oklahoma City]]]]
[[File:West Indian Manatee Skull.jpg|thumb|left|Skull of a West Indian manatee, the Museum of Osteology, Oklahoma City]]

Manatees weigh {{convert|400|to|550|kg|lb|abbr=on}}, and average {{convert|2.8|to|3.0|m|ftin|abbr=on}} in length, sometimes growing to {{convert|4.6|m|ftin|abbr=on}} and {{convert|1775|kg|lb|abbr=on}} and females tend to be larger and heavier than males. At birth, baby manatees weigh about {{convert|30|kg|lb|abbr=on}} each. The female manatee has two teats, one under each flipper,<ref>{{cite web|url=http://www.amyhremleyfoundation.org/php/education/impacts/Manatee.php|title=The Florida Manatee (''Trichechus manatus latirostrus'')|publisher=The Amy H Remley Foundation|access-date=August 15, 2013|archive-url=https://web.archive.org/web/20140222212950/http://www.amyhremleyfoundation.org/php/education/impacts/Manatee.php|archive-date=February 22, 2014|url-status=dead}}</ref> a characteristic that was used to make early links between the manatee and elephants.

The lids of manatees' small, widely spaced eyes close in a circular manner. The manatee has a large, flexible, [[prehensility|prehensile]] upper lip, used to gather food and eat and for social interaction and communication. Manatees have shorter snouts than their fellow [[sirenia]]ns, the [[dugong]]s.

{{Anchor|Teeth}}
Manatee adults have no [[incisor]] or [[canine tooth|canine]] teeth, just a set of cheek teeth, which are not clearly differentiated into [[Molar (tooth)|molars]] and [[premolar]]s. These teeth are [[polyphyodont|repeatedly replaced throughout life]], with new teeth growing at the rear as older teeth fall out from farther forward in the mouth, somewhat as [[elephant]]s' teeth do.<ref>{{Cite book|editor=Shoshani, J.|year=2000|title=Elephants: Majestic Creatures of the Wild|publisher=Checkmark Books|isbn=0-87596-143-6}}</ref><ref name="EoM"/> At any time, a manatee typically has no more than six teeth in each jaw of its mouth.<ref name=EoM/>

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]],<ref>{{cite journal|last1=Hautier|first1=Lionel|journal=PNAS|year=2010|volume=107|issue=44|pages=18903–18908|pmid=20956304|last2=Weisbecker|first2=V|last3=Sánchez-Villagra|first3=M. R.|last4=Goswami|first4=A|last5=Asher|first5=R. J.|title=Skeletal development in sloths and the evolution of mammalian vertebral patterning|doi=10.1073/pnas.1010335107|pmc=2973901|bibcode=2010PNAS..10718903H|doi-access=free}}</ref> a number that may be due to mutations in the [[homeotic genes]].<ref>{{cite web|title=Sticking Their Necks out for Evolution: Why Sloths and Manatees Have Unusually Long (or Short) Necks|url=https://www.sciencedaily.com/releases/2011/05/110505212314.htm|work=May 6th 2011|publisher=Science Daily|access-date=25 July 2013|archive-date=26 April 2019|archive-url=https://web.archive.org/web/20190426223708/https://www.sciencedaily.com/releases/2011/05/110505212314.htm|url-status=live}}</ref> All other mammals have seven cervical vertebrae,<ref>{{cite journal |pmid=10327647 |author=Frietson Galis |year=1999 |title=Why do almost all mammals have seven cervical vertebrae? Developmental constraints, Hox genes and Cancer |journal=Journal of Experimental Zoology |url=http://wwworm.biology.uh.edu/evodevo/lecture11/galis99.pdf |archive-url=https://web.archive.org/web/20041110200159/http://wwworm.biology.uh.edu/evodevo/lecture11/galis99.pdf |url-status=dead |archive-date=2004-11-10 |volume=285 |issue=1 |pages=19–26 |doi=10.1002/(SICI)1097-010X(19990415)285:1<19::AID-JEZ3>3.0.CO;2-Z |bibcode=1999JEZ...285...19G }}</ref> other than the [[two-toed sloth|two-toed]] and [[three-toed sloth]]s.

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.<ref>{{Cite web|title=Manatee Anatomy Facts|url=http://manatipr.org/wp-content/uploads/2014/08/SMC-ManateeAnatomyFacts.pdf|access-date=2021-12-24|archive-date=2021-12-26|archive-url=https://web.archive.org/web/20211226175025/http://manatipr.org/wp-content/uploads/2014/08/SMC-ManateeAnatomyFacts.pdf|url-status=live}}</ref>

=== Evolution ===
Fossil remains of manatee ancestors - also known as [[sirenia]]ns - date back to the [[Eocene|Early Eocene]].<ref name=":0">{{Cite book|title=Ecology and Conservation of the Sirenia : Dugongs and Manatees.|last=Marsh, Helene.|date=2011|publisher=Cambridge University Press|others=O'Shea, Thomas J., Reynolds III, John E.|isbn=978-1-139-15887-9|location=Cambridge|oclc=782876868}}</ref><ref>{{Cite journal|last1=de Souza|first1=Érica Martinha Silva|last2=Freitas|first2=Lucas|last3=da Silva Ramos|first3=Elisa Karen|last4=Selleghin-Veiga|first4=Giovanna|last5=Rachid-Ribeiro|first5=Michelle Carneiro|last6=Silva|first6=Felipe André|last7=Marmontel|first7=Miriam|last8=dos Santos|first8=Fabrício Rodrigues|last9=Laudisoit|first9=Anne|last10=Verheyen|first10=Erik|last11=Domning|first11=Daryl P.|date=2021-02-11|title=The evolutionary history of manatees told by their mitogenomes|journal=Scientific Reports|language=en|volume=11|issue=1|pages=3564|doi=10.1038/s41598-021-82390-2|pmid=33574363|issn=2045-2322|pmc=7878490|bibcode=2021NatSR..11.3564D}}</ref> It is thought that they reached the isolated area of the South American continent and became known as [[Trichechidae]]. In the [[Late Miocene]], [[Trichechidae|trichechids]] were likely restricted in South American coastal rivers and they fed on many freshwater plants. [[Dugong]]s inhabited the West Atlantic and Caribbean waters and fed on [[seagrass meadow]]s instead. As the sea grasses began to grow, manatees adapted to the changing environment by growing supernumerary molars. Sea levels lowered and increased erosion and silt runoff was caused by [[glaciation]]. This increased the tooth wear of the bottom-feeding manatees.<ref>{{Cite journal|title=Evolution of Manatees: A Speculative History|url=https://www.jstor.org/stable/1304394|journal=Journal of Paleontology|jstor = 1304394|last1 = Domning|first1 = Daryl P.|year = 1982|volume = 56|issue = 3|pages = 599–619}}</ref>