By Antonia Gorog
Geographic Range
Amazon Basin of Brazil, Colombia, Ecuador, Guyana, and Peru.
Biogeographic Regions:
neotropical
(native
).
Habitat
Amaxonian manatees inhabit the dense vegetation in blackwater lakes, oxbows, and lagoons.
These animals are found in the following types of habitat:
tropical
; freshwater
.
Aquatic Biomes:
lakes and ponds; rivers and streams; coastal
.
Physical Description
The Amazon ox manatee is gray and bears a white patch on its chest or several white markings on its chest and abdomen. Its body is covered with fine hairs and its upper and lower lips are covered with thick bristles. It has two axillary mammae. The largest manatee recorded was a male 2.8m in length.
Some key physical features:
endothermic
; bilateral symmetry
.
Reproduction
These manatees breed throughout the year and gestate for approximately one year. Usually one young is born. An individual thought to be a newborn measured 739mm in length. The mothern and calf have a long-lasting bond. The mother may carry the young on her back or clasped to her side. The lifespan of this animal is unknown, but individuals have lived past twelve and a half years in captivity.
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate); sexual
.
Behavior
The Amazon ox manatee is a gregarious animal and was once known to occur in large herds. However, as a result of severe overhunting, groups seen today contain no more than 4 to 8 individuals. This animal is both noctural and diurnal and lives its life almost entirely underwater. Only its nostrils protrude from the surface of the water as this animal searches river and lake bottoms for lush vegetation. Trichechus inunguis can eat up to eight percent of their body weight in aquatic vegetation in one day. Most feeding occurs during the wet season, when the manatees graze upon new plants in seasonally flooded backwaters. When the animals return to the main water courses during the dry season, they may not eat for weeks.
Amazon ox manatees are preyed upon by jaguars, sharks, and crocodiles.
Key behaviors:
motile
.
Food Habits
Trichechus inunguis feeds upon aquatic vegetation such as grasses, water lettuce (Pisitia), and water hyacinths. It is also known to eat floating palm fruits. Captives are capable of eating 9 to 15 kilograms of leafy vegetables per day.
Economic Importance for Humans: Negative
None
Economic Importance for Humans: Positive
Manatees are a source of food for many native peoples.
Conservation Status
Trichechus inunguis is listed as Cites-Appendix I, as U.S. E.S.A.-Endangered, and as IUCN-Vulnerable. They have been hunted by Amazonian Indians with nets and harpoons for centuries. In the 1930s and 1940s they were killed by the thousands for their hides, which were used to make water hoses and machine belts.
Other Comments
The earliest known fossils of the genus Trichechus are from Pleistocene deposits in the eastern United States and Argentina.
For More Information
Find Trichechus inunguis information at
Contributors
Antonia Gorog (author), University of Michigan.

