Animal Diversity Web

Ge­o­graphic Range

Trichechus sene­galen­sis oc­curs along the west coast of Africa. The Sene­gal River marks the north­ern limit of their range while the Cuanza River of An­gola serves as the south­ern bound­ary.

• Biogeographic Regions
• ethiopian
  • native
• atlantic ocean
  • native

Habi­tat

Trichechus sene­galen­sis are found in shal­low coastal wasters and fresh­wa­ter rivers. They ap­pear to pre­fer large, shal­low es­tu­ar­ies and weedy swamps, and have been re­ported to avoid salt water (Nowak 1991 and Nishi­waki 1984). Their range is lim­ited by tem­per­a­ture. They are rarely found in wa­ters of less than 18 de­grees cel­sius (Nowak 1991).

• Habitat Regions
• tropical
• saltwater or marine
• freshwater

• Aquatic Biomes
• rivers and streams
• coastal
• brackish water

• Other Habitat Features
• estuarine

Phys­i­cal De­scrip­tion

• Other Physical Features
• endothermic
• bilateral symmetry

Re­pro­duc­tion

Trichechus sene­galen­sis is a poorly stud­ied species, and much of the in­for­ma­tion about their be­hav­ior and re­pro­duc­tion has been in­ferred based on their close sim­i­lar­ity to the very well stud­ied Trichechus man­a­tus. They are ca­pa­ble of re­pro­duc­ing through­out the year; how­ever, a peak in calv­ing tends to occur in late spring or early sum­mer (CMC 1997). Fe­males are sex­u­ally ma­ture as early as three years of age. A fe­male in es­trus is joined by a dozen or more males. To­gether they form a mat­ing group in which cop­u­la­tion ap­pears to occur at ran­dom (Save the Man­a­tee Club 1997). Ges­ta­tion lasts about 13 months and usu­ally a sin­gle calf is born at a time, but twins do occur oc­ca­sion­ally. Calves are born tail first, and they can swim on their own (CMC 1997). They feed from a pair of pec­toral mam­mary glands. Trichechus sene­galen­sis are be­lieved to live to about 30 years of age, and fe­males can bear young every three to five years (Sikes 1974 and CMC 1997).

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual

Be­hav­ior

Again, the be­hav­ior of this species is poorly stud­ied. They are be­lieved to be at least par­tially noc­tur­nal, as this is when most hunters suc­cess­fully take man­a­tees (Sikes 1974). Trichechus sene­galen­sis may live singly or in fam­ily groups of up to four to six in­di­vid­u­als (Nowak 1991). They have few nat­ural preda­tors, and per­haps as a re­sult they do not have a very so­phis­ti­cated so­cial sys­tem. The strongest bond be­tween in­di­vid­u­als oc­curs be­tween a mother and her calf. Calves may re­main de­pen­dent on their moth­ers for up to two years (Save the Man­a­tee Club 1997).

• Key Behaviors
• motile

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• tactile
• chemical

Food Habits

Trichechus sene­galen­sis feeds pri­mar­ily on aquatic veg­e­ta­tion, and adults may con­sume up to 8000kg per year. They may also feed on over­hang­ing bank growth, and pop­u­la­tions liv­ing in es­tu­ar­ine en­vi­ron­ments are re­ported to feed ex­clu­sively on man­groves (Nowak 1991). In many areas, local fish­er­men claim that Trichechus sene­galen­sis are re­spon­si­ble for steal­ing fish from nets. How­ever, this be­hav­ior has yet to be con­firmed (Reeves et. al. 1988). Trichechus sene­galen­sis are de­pen­dent upon mi­croor­gan­isms liv­ing in their large in­testines to aid in the di­ges­tion of cer­tain plant ma­te­ri­als (Rath­bun 1990).

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Vil­lagers in Sierra Leone and Nige­ria hunt Trichechus sene­galen­sis for their meat (Reeves et. al. 1988). They have de­vel­oped elab­o­rate means of trap­ping the an­i­mals which they even­tu­ally kill with har­poons or guns (Sikes 1974 and Robin­son 1971). In con­trast to this, vil­lagers in Cameroon have a dif­fer­ent per­cep­tion of Trichechus sene­galen­sis. They do not like the taste of the meat and they be­lieve that Trichechus sene­galen­sis are fierce an­i­mals that be­come vi­o­lent when at­tacked. Niger­ian fish­er­men are often re­spon­si­ble for the poach­ing of Trichechus sene­galen­sis in Cameroon (Gri­gione 1996). It has also been re­ported that the skin of Trichechus sene­galen­sis has med­i­c­i­nal and ther­a­peu­tic prop­er­ties (Reeeves et. al. 1988).

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Vil­lagers in Sierra Leone con­sider Trichechus sene­galen­sis a major pest of rice crops. Fish­er­men be­lieve these an­i­mals are re­spon­si­ble for re­mov­ing fish from nets, but this is un­con­firmed (Reeves et. al. 1988).

Con­ser­va­tion Sta­tus

• IUCN Red List

  Vulnerable
  More information

Other Com­ments

Trichechus sene­galen­sis are the source of many myths and leg­ends. They have often been mis­taken for mer­maids. The blub­ber is be­lieved to have cu­ra­tive pow­ers and pos­ses­sion of body parts, es­pe­cially the skull and teeth, is be­lieved to con­fer spe­cial sta­tus in many as­pects of life, in­clud­ing sports, pol­i­tics, and aca­d­e­mics (Sikes 1974).

They are known in West Africa as "dikunge" and "peixe-muh­ler".

Con­trib­u­tors

Ethan Kane (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Cen­ter for Ma­rine Con­ser­va­tion. 1997. Man­a­tees and Dugongs. http:// www.​cmc-ocean.​org./22231m2_­man­a­tee.html

Gri­gione, M. M. 1996. Ob­ser­va­tions on the Sta­tus and Dis­tri­b­u­tion of the West African Man­a­tee in Cameroon. African Jour­nal of Ecol­ogy, 34:189-195.

Nishi­waki, M. 1984. Cur­rent Sta­tus of the African Man­a­tee. Acta Zo­o­log­ica Fen­nica, 172:135-136.

Nowak, R. M. 1991. Walker's Mam­mals of the World. Fifth Edi­tion. Johns Hop­kins Uni­ver­sity Press, Bal­ti­more.

Rath­bun, G. B. 1990. Man­a­tees. Grz­imek's En­cy­clo­pe­dia of Mam­mals. Mc­Graw-Hill, New York.

Reeves, R. R., D. Tuboku-Met­zger, and R. A. Kapindi. 1988. Dis­tri­b­u­tion and Ex­ploita­tion of Man­a­tees in Sierra Leone. Oryx, 22:75-84.

Robin­son, P. T. 1971. Wildlife Trends in Liberia and Sierra Leone. Oryx, 11:117-122.

Save the Man­a­tee Club. 1997. Mem­ber­ship Hand­book. Mait­land, Florida.

Sikes, S. 1974. How to Save the Mer­maids. Oryx, 12:465-470.