Animal Diversity Web

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.

• Habitat Regions
• 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.

• Other Physical Features
• endothermic
• bilateral symmetry

• Average mass

  480000 g

  16916.30 oz

  AnAge

• Average basal metabolic rate

  55.015 W

  AnAge

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

• Average number of offspring

  1

  AnAge

• Average gestation period

  328 days

  AnAge

• Average age at sexual or reproductive maturity (female)
  Sex: female

  1096 days

  AnAge

• Average age at sexual or reproductive maturity (male)
  Sex: male

  1096 days

  AnAge

Lifes­pan/Longevity

• Average lifespan
  Status: captivity

  12.5 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: wild

  30.0 years

  Max Planck Institute for Demographic Research

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

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• tactile
• chemical

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

None

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.

• IUCN Red List

  Vulnerable
  More information

Other Com­ments

The ear­li­est known fos­sils of the genus Trichechus are from Pleis­tocene de­posits in the east­ern United States and Ar­gentina.

Con­trib­u­tors

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

Ref­er­ences

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.