Systematics and Taxonomy
The West Indian manatee, Trichechus manatus Linnaeus, 1758, is one of four living species of the mammalian Order Sirenia. The other three sirenians are the West African manatee (T. senegalensis), the Amazonian manatee (T. inunguis), and the dugong (Dugong dugon). All four species are aquatic herbivores listed as endangered or threatened throughout their ranges by the U.S. Fish and Wildlife Service (USFWS 2001). A fifth species, Steller’s sea cow (Hydrodamalis gigas), once lived in sub-Arctic waters of the Bering Sea. Steller’s sea cow was a toothless sirenian that fed on kelp and reached lengths of up to 8 m (26 ft). It was hunted to extinction within 27 years of its discovery in 1741 (Reynolds and Odell 1991, cited in USFWS 2001).
Two subspecies of West Indian manatee are now recognized (Domning and Hayek 1986, cited in USFWS 2001; USFWS 2001, 2007): the Florida manatee, T. manatus latirostris, which occurs in the southeastern United States, and the Antillean manatee, T. manatus manatus, found throughout the remainder of the species’ range. The Florida manatee was originally described as a distinct species, Manatus latirostris, but for many decades now has been recognized as a subspecies of T. manatus. The historical ranges of the two subspecies may overlap on the coast of Texas, where the origin of occasional strays (from Florida or Mexico) is uncertain.
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