African Manatee

African Manatee - Trichechus Senegalensis

African Manatee – Trichechus Senegalensis

The African manatee (Trichechus senegalensis), also known as the West African manatee or seacow, is a species of manatee; it is mostly herbivorous (eats plants). African manatees can be found in much of the western region of Africa, from Senegal to Angola.[2] Scientists do not know a lot about this species, but they hypothesize the African manatee is very similar to the West Indian manatee (Trichechus manatus).[3]

Taxonomy

The African manatee was officially declared a species under the Trichechus senegalensis taxon in 1795 by the naturalist, Johann Heinrich Friedrich Link. No subspecies of this taxon are known, but unreliable claims have been made that there are morphological disparities between coastal manatee populations and isolated inland populations. After more research, no genetic evidence supports these claims and form any subspecies.[1] The African manatee falls under the Trichechus genus with only two other species, the Amazonian manatee and the West Indian manatee, which are also sirenians.[4]

Range and habitat

African manatees can be found in much of the western region of Africa such as in AngolaBeninCameroonChad, the Republic of the Congo, the Democratic Republic of the CongoCôte d’IvoireEquatorial GuineaGabonThe GambiaGhanaGuineaGuinea-BissauLiberiaMaliMauritaniaNigerNigeriaSenegalSierra Leone and Togo. Not only are these manatees found in many countries, but also in bodies of water ranging from brackish to freshwater. They can be found in oceans, rivers, lakes, coastal estuaries, reservoirs, lagoons, and calm shallow bays on the coast.[1]However, a limiting factor of where the African manatee can live is temperature. It is very rare to find an African manatee in water with a temperature below 18 °C (64 °F).[5]

Some are located along the west coast of Africa, in the southeastern and central eastern waters of the Atlantic Ocean. Manatees have been found as far offshore as 75 kilometres (47 mi) out, where there are shallow coastal flats and calm mangrove creeks filled with seagrass. Lakes where they dwell include Lake VoltaInner Niger River Delta in Mali, Lake Léré, and Lake de Tréné. Due to fluctuating flow rates and water levels in rivers, some of these permanent lakes serve as refuges, during the dry season, to manatees in connecting rivers. From north to south, the river systems that they can be found include the SenegalSaloumGambiaCasamance, Cacheu, Mansôa, Geba, Buba, Tombali, Cacine, Kogon, Kondoure, Sierra Leone, Great Scarcies, Little Scarcies, Sherbro, Malem, Waanje, Sewa, Missunado, CavallaSt. Paul, Morro, St. JohnBandama, Niouniourou, Sassandra, Comoé, BiaTanoVoltaMonoOuemeNigerMekrouBenue, Cross, Katsena AlaBaniAkwayafe, Rio del Rey, Ngosso, Andokat, Mene, Munaya, WouriSanaga, Faro, Chari, Bamaingui, Bahr-Kieta, LogonéMitéméléGabon, Ogoué, Lovanzi, KouilouCongo, Dande, Bengo, and Cuanza. They go up these rivers until they are unable to proceed due to water that is too shallow for them to swim through or strong waterfalls they cannot pass.[1]

Both African and West Indian manatees need habitats with protected water and access to food and fresh water. They occasionally journey to less-sheltered areas. Of all of their habitats in Africa, the most populated areas seem to be Guinea-Bissau, the lagoons of Côte d’Ivoire, the southern portions of the Niger River in Nigeria, Sanaga River in Cameroon, coastal lagoons in Gabon, and the lower parts of the Congo River. A study was done in Côte d’Ivoire to find where most African manatees favoured living. They were radio-tagged and tracked, and then they were sighted the most in coastal lagoons with plenty of their main food source, mangroves and other herbaceous growths. They were also found in grass-lined estuaries of big rivers with plenty of mangroves, and in protected coastal spots with less than 3 metres (10 ft) of water, again, with bountiful mangroves and also marine macrophytes.[1]

Diet

Although generally speaking, manatees are herbivores, the African manatee also eats clams, mollusks, and fish they find in nets. The majority of the diet of the African manatee is composed of many different types of flora found above or hanging over the water, instead of submerged. African manatees inhabiting rivers eat mostly overhanging plants growing on the river banks. The diets of African manatees living in estuaries consist of just mangrove trees. Each day, the African manatee will eat about 4 to 9 percent of its body weight in wet vegetation.[2][3] Microorganisms in the African manatee’s long large intestine (which measures up to 20 metres or 66 feet in length) aid the manatee in digesting the large quantity and variety of vegetation it takes in every day.[5]

Description

The shape of an African manatee’s body is such that it is “full around the middle and narrowing to a paddle-shaped tail”. It is grey in colour, with small, colourless hairs around its body. However, algae and other tiny organisms often grow on them, so they appear brown or greenish. Calves, however, are darker in colour when they are very young.[2][5][6] In length, African manatees measure up to 4.5 m (14.6 ft), and they weigh about 360 kg (790 lb).[3] African manatees are extremely slow, moving at between 4.8 and 8.0 km (3 and 5 mi) an hour, unless they fear predators, when they can travel at speeds of about 32 km (20 mi) an hour. The African manatee’s large forelimbs, or flippers, are used to paddle and to bring food to the manatee’s mouth, after which the vegetation is chewed by its strong molars, which are the only teeth it has. Each jaw has two vestigial incisors when the manatee is born, which it loses as it matures.[6] If the African manatee’s molars happen to fall out, new molars grow in their place. The manatee’s flippers, which bear nails, are also used “to embrace and touch other manatees”. The African manatee does not have any hindlimbs.[5][7][8][9] By looking at the exterior of the African manatee, one would not be able to distinguish it from the American manatee, however it is different from the Amazonian manatee, which has characteristic white markings on its abdomen.[8]

Evolution and legends

A form descendents of “coastal South American trichechids” of the late time of Pliocene is believed to have “reached West Africa by way of transoceanic currents, perhaps since the late Pliocene, to give rise to the West African manatee.”[10]

According to people of western Africa, Maame (also spelled Mami) Water, a recurring character in many coastal legends, is a goddess of the sea, and a symbol of wealth and beauty. Contrasting with this depiction, Maame Water also flips over canoes and entices their occupants to come “down to her watery kingdom”. Scientists from the Institute of Aquatic Biology of the Centre for Scientific and Industrial Research (CSIR) and the Wildlife Department in Ghana have drawn the conclusion that Maame Water is not a sea goddess, in fact, but the West African manatee. According to Dr. Mamaa Entsua-Mensah, who performs research for CSIR, “the female manatee looks like a woman when they [sic] surface to inhale fresh air at night.” Entsua-Mensah said “because of the breast with teats, when people sight the mammals jumping out of the sea in the night to take in long deep breath of air, they are perceived as half woman, half fish.” It was not allowed to openly speak of the sacred goddess Maame Water except after certain rituals. In Nigeria, stories are passed through generations concerning “persons whose fortunes have changed dramatically when they married Maame Water, the mermaid, but lost everything when they became unfaithful to her”.[11]

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