The African manatee (''Trichechus senegalensis''), also known as the West African manatee, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
manatee
Manatees (family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species ...
that inhabits much of the western region of Africa – from
. It is the only manatee species to be found in the
Old World
The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...
. Not a great deal is known about ''T. senegalensis.''
Taxonomy
The African manatee was officially declared a species under the ''Trichechus senegalensis''
taxon
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
in 1795 by naturalist
Johann Heinrich Friedrich Link
Johann Heinrich Friedrich Link (2 February 1767 – 1 January 1851) was a German naturalist and botanist.
Biography
Link was born at Hildesheim as a son of the minister August Heinrich Link (1738–1783), who taught him love of nature throug ...
. No
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of this taxon are known. Although African manatees live in both coastal areas and isolated inland areas, genetic evidence suggests no significant differences between the two populations. The African manatee falls under the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Trichechus'' with only two other
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, the
Amazonian manatee
The Amazonian manatee (''Trichechus inunguis'') is a species of manatee that lives in the Amazon Basin in Brazil, Peru, Colombia and Ecuador. It has thin, wrinkled brownish or gray colored skin, with fine hairs scattered over its body and a whit ...
and the
West Indian manatee
The West Indian manatee (''Trichechus manatus''), also known as the North American manatee, is a large, aquatic mammal native to warm coastal areas of the Caribbean, from the eastern US to northern Brazil. Living alone or in herds, it feeds on un ...
, which are also
sirenians
The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct f ...
.
Range and habitat
African manatees inhabit the widest ranges of habitats of any sirenian species, ranging from offshore islands in the Atlantic, rivers in the western Sahel, equatorial rainforest rivers, and so on. It has been reported that coastal populations ascend rivers during the rainy season and subsequently descend again during the dry season. The movement and habitat of the African manatee has been threatened by the building of agricultural and hydroelectric dams along rivers that isolate populations, such as the
Akosombo Dam
The Akosombo Dam, also known as the Volta Dam, is a hydroelectric dam on the Volta River in southeastern Ghana in the Akosombo gorge and part of the Volta River Authority. The construction of the dam flooded part of the Volta River Basin and led ...
in Ghana. The
Diama Dam
The Diama Dam, sometimes referred to as the Maka–Diama Dam, is a gravity dam on the Senegal River, spanning the border of Senegal and Mauritania. It is located next to the town of Diama, Senegal and about north of Saint-Louis, Senegal. The ...
has permanently isolated the Senegal River manatee population from the coast, as has the Felou Dam in Mali.
African Manatees can be found in West African regions:
Benin
Benin ( , ; french: Bénin , ff, Benen), officially the Republic of Benin (french: République du Bénin), and formerly Dahomey, is a country in West Africa. It is bordered by Togo to the west, Nigeria to the east, Burkina Faso to the north ...
,
Cameroon
Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
,
Chad
Chad (; ar, تشاد , ; french: Tchad, ), officially the Republic of Chad, '; ) is a landlocked country at the crossroads of North and Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic ...
, the
Republic of the Congo
The Republic of the Congo (french: République du Congo, ln, Republíki ya Kongó), also known as Congo-Brazzaville, the Congo Republic or simply either Congo or the Congo, is a country located in the western coast of Central Africa to the w ...
, the
Democratic Republic of the Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
,
Côte d'Ivoire
Ivory Coast, also known as Côte d'Ivoire, officially the Republic of Côte d'Ivoire, is a country on the southern coast of West Africa. Its capital is Yamoussoukro, in the centre of the country, while its largest city and economic centre is ...
,
Equatorial Guinea
Equatorial Guinea ( es, Guinea Ecuatorial; french: Guinée équatoriale; pt, Guiné Equatorial), officially the Republic of Equatorial Guinea ( es, link=no, República de Guinea Ecuatorial, french: link=no, République de Guinée équatoria ...
,
Gabon
Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the north ...
,
The Gambia
The Gambia,, ff, Gammbi, ar, غامبيا officially the Republic of The Gambia, is a country in West Africa. It is the smallest country within mainland AfricaHoare, Ben. (2002) ''The Kingfisher A-Z Encyclopedia'', Kingfisher Publicatio ...
,
Ghana
Ghana (; tw, Gaana, ee, Gana), officially the Republic of Ghana, is a country in West Africa. It abuts the Gulf of Guinea and the Atlantic Ocean to the south, sharing borders with Ivory Coast in the west, Burkina Faso in the north, and To ...
,
Guinea
Guinea ( ),, fuf, 𞤘𞤭𞤲𞤫, italic=no, Gine, wo, Gine, nqo, ߖߌ߬ߣߍ߫, bm, Gine officially the Republic of Guinea (french: République de Guinée), is a coastal country in West Africa. It borders the Atlantic Ocean to the we ...
,
Guinea-Bissau
Guinea-Bissau ( ; pt, Guiné-Bissau; ff, italic=no, 𞤘𞤭𞤲𞤫 𞤄𞤭𞤧𞤢𞥄𞤱𞤮, Gine-Bisaawo, script=Adlm; Mandinka: ''Gine-Bisawo''), officially the Republic of Guinea-Bissau ( pt, República da Guiné-Bissau, links=no ) ...
,
Liberia
Liberia (), officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to its north, Ivory Coast to its east, and the Atlantic Ocean ...
,
Mali
Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Mali ...
,
Mauritania
Mauritania (; ar, موريتانيا, ', french: Mauritanie; Berber: ''Agawej'' or ''Cengit''; Pulaar: ''Moritani''; Wolof: ''Gànnaar''; Soninke:), officially the Islamic Republic of Mauritania ( ar, الجمهورية الإسلامية ...
,
Niger
)
, official_languages =
, languages_type = National languagesNigeria
Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...
Sierra Leone
Sierra Leone,)]. officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It is bordered by Liberia to the southeast and Guinea surrounds the northern half of the nation. Covering a total area of , Sierra ...
, and
Togo
Togo (), officially the Togolese Republic (french: République togolaise), is a country in West Africa. It is bordered by Ghana to the west, Benin to the east and Burkina Faso to the north. It extends south to the Gulf of Guinea, where its c ...
. Manatees are found in
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
waters to freshwater: in oceans, rivers, lakes, coastal estuaries, reservoirs, lagoons, and bays on the coast. African manatees rarely inhabit waters with a temperature below
Manatees have been found as far as offshore, where there are shallow coastal flats and calm
mangrove
A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...
Lake Léré
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
, and Lake de Tréné. Due to fluctuating flow rates and water levels in rivers, some of these permanent lakes serve as refuges for manatees in connecting rivers during the dry season. From north to south, the river systems that contain manatees include: the
Saloum
The Kingdom of Saloum (Serer language: ''Saluum'' or ''Saalum'') was a Serer people, Serer/Wolof people, Wolof monarchy, kingdom in present-day Senegal. Its kings may have been of Mandinka people, Mandinka/Kaabu origin. The capital of Saloum wa ...
,
Gambia
The Gambia,, ff, Gammbi, ar, غامبيا officially the Republic of The Gambia, is a country in West Africa. It is the smallest country within mainland AfricaHoare, Ben. (2002) ''The Kingfisher A-Z Encyclopedia'', Kingfisher Publicatio ...
,
Casamance
, settlement_type = Geographical region
, image_skyline = Senegal Casamance.png
, image_caption = Casamance in Senegal
, image_flag = Flag of Casamance.svg
, image_shield =
, motto ...
Konkouré
''For the river having its source near the town, see Konkouré River''
Konkouré is a town and sub-prefecture in the Mamou Prefecture in the Mamou Region
Mamou Region ( Pular: 𞤁𞤭𞥅𞤱𞤢𞤤 𞤃𞤢𞥄𞤥𞤵𞤲) is locate ...
,
Sierra Leone
Sierra Leone,)]. officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It is bordered by Liberia to the southeast and Guinea surrounds the northern half of the nation. Covering a total area of , Sierra ...
Bandama
The Bandama River is the longest river in Ivory Coast with a length of some 800 kilometers. The south-flowing river is fed by the Marahoué, Solomougou, Kan and Nzi rivers and empties into the Tagba Lagoon and the Gulf of Guinea.
The Bandama fl ...
, Niouniourou,
Sassandra
Sassandra is a town in southern Ivory Coast. It is a sub-prefecture of and the seat of Sassandra Department. It is also a commune and the seat of Gbôklé Region in Bas-Sassandra District.
Sassandra lies on the Gulf of Guinea at the mouth of th ...
Mono
Mono may refer to:
Common meanings
* Infectious mononucleosis, "the kissing disease"
* Monaural, monophonic sound reproduction, often shortened to mono
* Mono-, a numerical prefix representing anything single
Music Performers
* Mono (Japanese b ...
Cross
A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a sa ...
Bani
Bani may refer to:
Places Africa
*Bani Department, a department in the Séno Province of Burkina Faso
*Bani, Bani, Séno, Burkina Faso
* Bani, Bourzanga, Bam, Burkina Faso
*Bani, Gnagna, Burkina Faso
* Bani, The Gambia
*Bani River, a tributary ...
Rio del Rey
The Rio del Rey (also called Rio del Ray) is an estuary of a drainage basin in West Africa in Cameroon. It is located in the eastern area of the Niger River system.
Chari
Chari may refer to:
Places
* Chari River, in Central Africa
* Chari-Baguirmi (disambiguation), in Chad
* Chari Department, in Chad, one of three departments making up the region of Chari-Baguirmi
* Moyen-Chari (disambiguation), in Chad
* Chari, ...
Gabon
Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the north ...
Dande
Dande, with its capital at Barra do Dande, is a municipality in Bengo Province in Angola.
Subdivisions
Dande comprises seven communes as follows.
* Caxito
* Barra do Dande
Barra do Dande is a town, with a population of 75,000 (2014), and a com ...
, Bengo, and Cuanza. Manatees move up these rivers until they are unable to proceed because of shallow waters or strong waterfalls.
The areas with the highest manatee populations are Guinea-Bissau, the lagoons of Côte d'Ivoire, the southern portions of the Niger River in Nigeria, the Sanaga River in Cameroon, the coastal lagoons in Gabon, and the lower parts of the Congo River. As part of a study completed in Côte d'Ivoire to assess where the majority of African manatees favor living, a sample of African manatees was radio-tagged and tracked. The tracking observed most of the sample in coastal lagoons, mangroves, and other
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of t ...
growths. They were also found in the grassy estuaries of big rivers with mangroves and in protected coastal spots with less than of water containing both mangroves and marine macrophytes.
Diet
Manatees are
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s; however, they also eat clams,
mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
s, and fish found in nets. The percentage of the diet that is composed of non-plant material varies based on location, with manatees living off the coast having a lifetime average of 50% non-plant material. The West African manatee is the only sirenian that seems to intentionally consume non-plant material. A majority of the African manatee's diet is made up of a variety of
flora
Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''.
E ...
found above or hanging over the water. African manatees that inhabit rivers mostly eat the overhanging plants growing on the river banks. The diet of African manatees living in estuaries consists solely of mangrove trees. Each day, the African manatee eats about four to nine percent of its body weight in wet vegetation. Microorganisms within the African manatee's large intestine, which measures up to in length, aid it in digesting the large quantity and variety of vegetation that it consumes daily.
Description
The African manatee's body is widest at the middle, and its tail resembles a paddle. The manatee is gray in color with small, colorless hairs that cover its body. However, algae and other tiny organisms often grow on an African manatee's body, so its body sometimes appears brown or greenish in color. Calves are darker in color when they are very young. African manatees measure up to in length, and weigh about . African manatees are typically extremely slow, moving between 4.8 km and 8.0 km (3 and 5 mi) per hour, although when scared by predators they can travel at speeds of about per hour. The African manatee's large forelimbs, or flippers, are used to paddle and to bring food to its mouth. Vegetation is then chewed by the manatee's strong molars, which are its only teeth. When the manatee is born, each jaw has two vestigial incisors, which the manatee loses as it matures. If the African manatee's molars happen to fall out, new molars grow in their place. The manatee's flippers, which have nails, are also used to graze other manatees. The African manatee does not have any hind limbs. From the exterior, the African manatee looks very similar to the American manatee; however, the African manatee is different from the Amazonian manatee, which has characteristic white markings on its abdomen.
Evolution and legends
The West African manatee is a descendant of trichechids found in coastal South America during the
Pliocene Epoch
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58
According to people of western Africa, ''Maame'' ''Water'' (also spelled '' Mami Wata''), a recurring character in many coastal legends, is a goddess of the sea and a symbol of wealth and beauty. ''Maame'' ''Water'' also flips over canoes and entices their occupants to visit her kingdom. Scientists from the Institute of Aquatic Biology of the Centre for Scientific and Industrial Research (CSIR) and the Wildlife Department in Ghana have concluded that ''Maame'' ''Water'' is based on the West African manatee. According to Dr. Mamaa Entsua-Mensah, who performs research for CSIR, when female African manatees surface for air, they resemble goddesses. Entsua-Mensah explains that the female manatee's breasts create the illusion of a woman-fish.
Among the
Serer people
The Serer people are a West African ethnoreligious group.
of Senegal, the Gambia and Mauritania, the manatee is regarded as sacred and highly respected, because in the
Serer creation myth
The Serer creation myth is the traditional creation myth of the Serer people of Senegal, the Gambia and Mauritania. Many Serers who adhere to the tenets of the Serer religion believe these narratives to be sacred. Some aspects of Serer religious a ...
, it is viewed as the guardian of the secrets of the future.
Behavior
The African manatee is
nocturnal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
. They tend to travel silently, eat, and be active towards the end of the day and during the nighttime. During the daytime, the African manatee dozes in shallow (1 to 2 meter deep) water. In countries such as Sierra Leone, African manatees migrate upstream when flooding occurs in June and July. This flooding can lower the availability of food for the manatees as well as lower the salinity of waterways. African manatees live in groups of 1 to 6. They have very few natural predators, two of which are sharks and crocodiles. They are also very social, spending a majority of their day bonding by touch, verbal communication, and smell. This creates a deep bond between them. When it is time to migrate due to a weather change, manatees will travel in larger groups to find warmer water and food.
Reproduction
The gender of an individual African manatee can only be determined by close examination of the manatee's underside. The only visible distinction between males and females is the genital openings. However, males tend to be smaller than females. Some female African manatees are sexually mature as young as 3 years of age, and they give birth every 3 to 5 years of their estimated 30-year lifespan. Males take a longer time to mature (about 9 to 10 years) and can rarely fertilize an egg at the age of 2 or 3 years. African manatees breed year-round. When males and females mate, it is not monogamous; multiple males will usually mate with one female. When the opportunity to mate with a female is at stake, males will fight with each other by pushing and shoving. Female African manatees give birth to one calf at a time after about a 13-month pregnancy. Calves can swim on their own at birth. Although the African manatee's social organization is not well understood, research shows the most common and tightly knit bonds are between a mother and her calf.
Threats
The African manatee is a vulnerable species because of its meat, oil, bones, and skin, which can bring great wealth to poachers. Specifically they are used to make walking sticks and toy spinning tops. In some countries, such as Nigeria and Cameroon, African manatees are sold to zoos, aquariums, online as pets, and they are sometimes shipped internationally. Anyone visiting such countries will notice manatee meat being sold on the streets and in marketplaces, but the lack of law enforcement protects the poachers from punishment. Residents of countries such as Mali and Chad depend on the oil of the African manatee to cure ailments such as ear infections,
rheumatism
Rheumatism or rheumatic disorders are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. Rheumatism does not designate any specific disorder, but covers at least 200 different conditions, including art ...
, and skin conditions.
There are even more threats to the African manatees' habitat and life: urban and agricultural development, increased damming, and increased use of hydroelectric power in the rivers of countries like Côte d'Ivoire and Ghana. The building of dams has led to genetic isolation of some populations. There is little data to show if this has any negative long-term effects on the population as a whole. At several hydroelectric dams including the Kanji dam on the Niger River and the Akosombo dam on the Volta River manatees have been caught and killed in the turbines and intake valves. Thick congestion of boats in waterways may cause the manatees to have deadly run-ins with the vessels. However, even natural occurrences, such as droughts and tidal changes, can often strand manatees in unsuitable habitats. Some are killed accidentally by fishing trawls and in nets which are intended for catching sharks.
Some behaviors of African manatees provoke humans to hunt them. When manatees become tangled in fishing nets, they can damage them. People in countries such as Sierra Leone believe that killing the manatees to reduce the species size lowers the chances of the fishing nets requiring expensive repairs. In addition, African manatees can destroy rice crops by drifting into fields during the rainy season.
Many of the African manatees that venture up the Niger River starve to death. At certain times each year, the Niger River dries up due to the hot temperatures and lack of rain. Many manatees migrate there during the rainy season. When the water dries up the manatees are unable to get to other bodies of water.
Conservation
From November 2004 until December 2007, the West African Manatee Conservation Project completed Phase I. During this phase, residents of six African countries (Mauritania, Senegal, The Gambia, Guinea, Guinea-Bissau, and Sierra Leone) created a database of previously unknown information about the species (such as population, economic value, and habitat range) by conducting surveys in their countries. Other African countries also contributed reports that broadened the collective knowledge of the African manatee. Because of the work done during this phase, the general public, young children, and experienced scientists alike are receiving better information than ever before as to how to protect the African manatees. Phase I also allowed for up-close examination of the African manatee's way of life through field work.
Due to the large-scale success of Phase I, a Phase II is to be enacted by
Wetlands International
Wetlands International is a global organisation that works to sustain and restore wetlands and their resources for people and biodiversity. It is an independent, not-for-profit, global organisation, supported by government and NGO membership from ...
. During Phase II, the information collected in Phase I will be even more widely distributed around the areas in which the African manatee lives. Phase II will focus on furthering the existing research and adjusting legislation and education.
The African manatee is listed on Appendix I of the Convention on International Trade in Endangered Species (
CITES
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
), meaning international export or import is strictly regulated. Laws exist to protect the African manatee in every country in which it lives, but these laws are not well enforced. Due to this mass lack of enforcement and minimal education, the African manatee population is being steadily depleted.