the Trichechus manatus lives in an aquatic ecosystem. more specifically, it is found in rivers, estuaries, and coastal waters. it feeds on sea grasses and other aquatic plants in shallow (usually less than 6 m) marine waters that are warm enough (above about 20 deg C (68 deg F) ) to support the manatee's low metabolic rate and clear enough for the manatee to see despite its poor vision. the Trichechus manatus has been spotted up to 6 km (3.7 mi) from the coast.
niche:
the manatee is the only fully aquatic mammal herbivores, and thus the primary consumer of plants in the coastal waters and estuaries in which it lives.
origin:
Eocene period (54-38 million years ago)
the manatee and its close relative in the order Sirenia, the dugong, originated from the a common ancestor -- a sea cow -- the Protosiren. this herbivore, not far removed from the elephant's lineage, was found in the warm underwater plains of the Atlantic and Caribbean.
Oligocene period (38-26 million years ago)
as the global climate cooled and the fertile sea grass areas shrunk dramatically, this species gradually met its end.
Miocene period (26-7 million years ago)
scientists believe that following this species' evolution, the manatees of the family Trichechidae appeared.
range:
usually found in tropical waters, places supporting an abundance of sea grass and other vegetation with warm, shallow water. coastal areas are generally warm year round and provide enough heat to allow the manatee a low metabolic rate.
in 1990 the Trichechus manatus was found in the following (highlighted green) areas:
population change:
as a result of human activities, the Trichechus manatus' current habitat has been greatly reduced. while the effect on the population is hard to quantify with the main method of population assessment (aerial, where the manatee often is impossible to see under water), the table below shows encouraging evidence even as accidental mortality (ie boat running over manatee) is on the rise.
in 2001 there were an estimated 3276 manatees in the four regions of Florida assessed. however, in 1990 this number was signifigantly lower, despite obvious increase in human activities in Florida.