Trichechus inunguisAmazonian manatee

Geographic Range

Amazon Basin of Brazil, Colombia, Ecuador, Guyana, and Peru.


Amaxonian manatees inhabit the dense vegetation in blackwater lakes, oxbows, and lagoons.

  • 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.

  • Average mass
    480000 g
    16916.30 oz
  • Average basal metabolic rate
    55.015 W


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
  • Average number of offspring
  • Average gestation period
    328 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1096 days
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1096 days



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.

Communication and Perception

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: Positive

Manatees are a source of food for many native peoples.

Economic Importance for Humans: Negative


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.


Antonia Gorog (author), University of Michigan-Ann Arbor.



living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


mainly lives in water that is not salty.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


Husar, Sandra L. 1977. Mammalian Species, No. 72. The American Society of Mammalogists, pp1-4.

Wilson, Don E. and Reeder, DeeAnn (ed.). 1993. Mammal Species of the World: A Taxonomic and Geographic Reference, 2nd edition, The Smithsonian Institution Press, Washington and London, p365.