Manatee - Trichechus manatus, is divided into two subspecies
based on skull anatomical differences, Trichechus manatus
latirostrus (Florida manatee) andTrichechus manatus
manatus (Antillean manatee). Each possessing 48 chromosomes.
manatee - Trichechus manatus latirostrus, reaches a possible
length of 3.9 meters and weight of 1,500 kilograms. They are generally gray to
dark-brown in color, with rough, bumpy skin.
manatee - Trichechus manatus manatus, is very close to the
Florida manatee in appearance, with a maximum length of 3.5 meters and weight of
1,000 kilograms. Externally, the subspecies are indistinguishable.
Manatee - Trichechus inunguis, the smallest of the living
manatees in length with the longest recorded measurement only 2.8 meters, lives
in the Amazon basin in South America. It typically bears small white or pink
patches on its smooth skin. Less obvious differences include: a lack of nails on
the pectoral flippers, longer flippers, smaller teeth, and a longer, narrower
rostrum (anterior skull) relative to other manatee species. This species is also
the only one confined to fresh water. Its total number of chromosomes is 56.
Manatee - Trichechus senegalensis, is roughly the same size as
a West Indian manatee, but has more protruding eyes, a blunter snout, a less
robust body, and a more downward-pointing rostrum. The chromosomal compliment is
Dugong - Dugong dugon,
with a maximum length of 3.3 meters and weight of 400 kilograms, is remarkably
different from the manatee in many ways. Dugongs have smooth skin, a split tail
fluke, and tusks which erupt in post-pubescent males only. They are the most
marine genus of Sirenians in habitat preference, and are the only indo-pacific
sirenians alive today, due to the human-caused extinction of the Stellar’s sea
cow during the late 1700’s.